Content uploaded by Dinesh Jaishankar
Author content
All content in this area was uploaded by Dinesh Jaishankar on Apr 20, 2017
Content may be subject to copyright.
OPEN ACCESS
| www.microbialcell.com 438 Microbial Cell | SEPTEMBER 2016 | Vol. 3 No. 9
www.microbialcell.com
Review
SPE
CIAL ISSUE ON SEXUALLY
TRANSMITTED INFECTIONS
ABSTRACT Etiology, transmission and protection: Herpes simplex virus-2
(HSV-2) is a leading cause of sexually transmitted infections with recurring
manifestations throughout the lifetime of infected hosts. Currently no effec-
tive vaccines or prophylactics exist that provide complete protection or im-
munity from the virus, which is endemic throughout the world. Patholo-
gy/Symptomatology: Primary and recurrent infections result in lesions and
inflammation around the genital area and the latter accounts for majority of
genital herpes instances. Immunocompromised patients including neonates
are susceptible to additional systemic infections including debilitating conse-
quences of nervous system inflammation. Epidemiology, incidence and preva-
lence: More than 500 million people are infected worldwide and most report-
ed cases involve the age groups between 16-40 years, which coincides with an
increase in sexual activity among this age group. While these numbers are an
estimate, the actual numbers may be underestimated as many people are
asymptomatic or do not report the symptoms. Treatment and curability: Cur-
rently prescribed medications, mostly nucleoside analogs, only reduce the
symptoms caused by an active infection, but do not eliminate the virus or
reduce latency. Therefore, no cure exists against genital herpes and infected
patients suffer from periodic recurrences of disease symptoms for their entire
lives. Molecular mechanisms of infection: The last few decades have generat-
ed many new advances in our understanding of the mechanisms that drive
HSV infection. The viral entry receptors such as nectin-1 and HVEM have been
identified, cytoskeletal signaling and membrane structures such as filopodia
have been directly implicated in viral entry, host motor proteins and their
viral ligands have been shown to facilitate capsid transport and many host
and HSV proteins have been identified that help with viral replication and
pathogenesis. New understanding has emerged on the role of autophagy and
other innate immune mechanisms that are subverted to enhance HSV patho-
genesis. This review summarizes our current understanding of HSV-2 and as-
sociated diseases and available or upcoming new treatments.
Genital Herpes: Insights into Sexually Transmitted
Infectious Disease
Dinesh Jaishankar
1,2,4
and Deepak Shukla
1,2,3,*
1,2
Departments of Bioengineering and Ophthalmology and Visual Sciences, University of Illinois at Chicago, IL 60612.
3
Department of Microbiology and Immunology, University of Illinois at Chicago, IL 60612.
4
Department of Pathology, University of Illinois at Chicago, IL 60612.
* Corresponding Author:
Deepak Shukla, E-mail: dshukla@uic.edu
INTRODUCTION
Genital herpes is one of the most common, persistent and
highly infectious sexually transmitted viral infections most-
ly caused by herpes simplex virus-2 (HSV-2) and in many
emerging first time cases, by HSV-1 [1]. Primary and recur-
rent genital herpes infections most commonly result in
lesions and inflammation around the genital area. In wom-
en, the sites of infection are mainly the vulva and the vagi-
na, with some cases involving the regions of cervix and
perianal. In heterosexual men infection is typically on the
glans or the shaft of the penis, whereas anal infection is
also reported with homosexual men. More than 500 mil-
lion people are infected worldwide and most cases report-
ed are among the age groups between 16-40 years that
doi: 10.15698/mic2016.09.528
Received originally: 09.11.2015;
in revised form: 24.12.2015,
Accepted 07.01.2016,
Published 27.06.2016.
Keywords: herpes simplex virus, virus
entry, viral glycoproteins, viral latency,
antivirals.
Abbreviations:
3-OST – 3-O-sulfotransferase,
g – glycoprotein,
HPSE - Heparanase
HS – heparan sulfate
HSPG – heparan sulfate proteoglycan,
ICP – infected cell protein,
LAT – latency associated transcripts,
NMIIA – non-muscle myosin II A
PILRα – paired immunoglobulin-like
type 2 receptor α;
D. Jaishankar and D.Shukla (2016) Genital Herpes and STI
OPEN ACCESS
| www.microbialcell.com 439 Microbial Cell | SEPTEMBER 2016 | Vol. 3 No. 9
coincides with increased sexual activity among this age
group [2]. While these numbers are an estimate, the actual
numbers may be underestimated as many people are ei-
ther asymptomatic or are unaware of the infection [3]. This
review provides an insight into the epidemiology, patholo-
gy, our current understanding of the molecular mecha-
nisms of infection and the currently available and upcom-
ing treatments for genital herpes.
EPIDEMIOLOGY AND PREVALENCE
Herpesviruses are among the most ubiquitous of human
infections. After infection with HSV, it is thought that the
virus and the immune response to the virus persist through
the life of the host. HSV infections are measured by testing
various populations for the presence of antibodies specific
to the virus. An estimated 90% of all people worldwide
have one or both viruses [4, 5]. HSV-1 is the more preva-
lent virus with 65% of persons in the United States having
antibodies to HSV-1 [6], while HSV-2 infections are marked-
ly less frequent, with 15%–80% of people in various popu-
lations infected [7]. HSV-1 and HSV-2 infection rates widely
vary between countries. The increase in genital HSV-1 is
mainly attributed to an increase in oral sex among young-
sters and adults which is viewed safer than intercourse [8].
Due to this, in the USA, Canada, and other European coun-
tries, at least half of the first episodes for genital herpes
have been caused by HSV-1 in the past decade [9-12]. In a
study performed by the CDC it is estimated that about one
in six Americans aged 14 to 49 are infected with HSV-2 and
the prevalence in women was 20.9%, twice as high as
among men [13]. While a surge of HSV-2 seroprevalence
from 16.4% to 21.8% was observed from 1976 to 1994 [14],
this trend has reversed, dropping to 17.2% in 2004 [15]. In
Africa and other developing countries, there is a high bur-
den of HSV-2 infections with >50% prevalence in the popu-
lation [16]. Around 82% of women and 53% of men in the
Sub-Saharan Africa are seropositive for HSV-2 [17]. HSV-2
infection rates also depend on the rates of sexual activity
and are more prevalent in heavily exposed populations,
such as commercial sex workers, who are nearly 100% pos-
itive, suggesting an urgent need for education and new
measures for prevention [18].
MOLECULAR MECHANISMS OF INFECTION
HSV are linear, double stranded DNA viruses capable of
establishing latency in humans. They belong to the family
of Herpesviridae and more specifically to the sub-family of
Alphaherpesvirinae. There are two sub-types: HSV-1 and
HSV-2 that are closely related but differ slightly in tissue
tropism and antigenic properties. The viral DNA is present
in the core that is enclosed in a protein shell called the
capsid (Fig. 1). The icosahedral shaped capsid is
~
125 nm
in diameter, which is connected to and surrounded by a
glycoprotein expressing lipid bilayer membrane envelope
via a protein coat called the tegument. The viral envelope
contains at least 12 glycoproteins many of which play ma-
jor roles in the entry and egress of the virus. A list of HSV
glycoproteins along with their reported functions is provid-
ed in Table 1.
FIGURE 1:
Schematic of HSV
-
1/HSV
-
2 lytic infe
c-
tion. The HSV-1/HSV-2 virion recognizes and
attaches to the heparan sulfate proteoglycan via
glycoproteins on the viral envelope. By a process
called ‘surfing’, the virus particles can travel
along filopodia-like membrane extensions to
reach the surface of the cell. On the surface of
the cell, viral capsid penetration can occur by
fusion of envelop with the plasma membrane (I),
or alternatively by endocytosis of enveloped
virions with eventual fusion of the envelope with
a vesicular membrane (II). In either case, gD on
the virus envelope is required via its interaction
with one of the receptors (shown in red): her-
pesvirus entry mediator (HVEM) or nectin-1 and-
2. In the cytoplasm, the capsid (brown) travels to
the nucleus where the viral DNA is released.
Multiple rounds of replication result in multiple
copies of viral DNA and other components that
get packaged and assembled in the nucleus.
During egress, the newly assembled capsid gets
its primary envelope at the peri-nuclear mem-
brane, which is lost during egress from the outer
nuclear membrane. Naked capsid travels
through the cytoplasm where it receives the
tegument and the viral envelope (presumably
from the Golgi or the ER). Heparanase (denoted
as pink spots) is an enzyme that was recently
described in aiding viral egress. The enzyme cleaves of cell surface heparan sulfate (dotted black) which clears the path for the virus to exit
the cell.
D. Jaishankar and D.Shukla (2016) Genital Herpes and STI
OPEN ACCESS
| www.microbialcell.com 440 Microbial Cell | SEPTEMBER 2016 | Vol. 3 No. 9
TABLE 1
.
List of HSV glycoproteins and their reported functions.
Glycoprotein Function References
gB Fusogenic protein: class III [23]
gC Attachment and C3b receptor [20, 24]
gD Virus entry and fusion [19, 21]
gE Virus spread and Fc receptor [22, 25]
gH Virus entry and fusion [19, 21]
gI Virus spread and Fc receptor [22, 26, 27]
gK Virus spread and egress [28, 29]
gL Viral entry and fusion [19, 24]
gM Virus assembly and fusion [30-32]
The lifecycle of HSV has been mostly studied and char-
acterized using HSV-1 infections. However, HSV-2 infec-
tions are considered similar to HSV-1 infections. Different
stages in the HSV lifecycle can be broadly classified into:
i. Attachment: Initiation of infection begins with the at-
tachment of viral glycoproteins to the cell surface. Heparan
sulfate proteoglycans (HSPGs) on the cells serve as attach-
ment sites for HSV [19]. Glycoproteins B and C (gB and gC)
on the HSV envelop bind to the HSPGs and are essential to
initiate attachment. A study by Herold et al., using a gB and
gC null virus showed reduction in the overall virus attach-
ment to the cells as well as reduction in virus infectivity
[20]. Moreover, it has been shown that in the absence of
gC gB can take over and help in attachment to cells, indi-
cating a gC-independent mode of viral attachment [33].
HSV was shown to bind to HS (heparan sulfate) on the filo-
podia, which are plasma membrane protrusions, and use
filopodial interaction to migrate towards the cell body to
initiate entry. This process was termed “viral surfing” [34].
In this study, viral particles were shown to surf along the
filopodia and the formation of filopodial structures in-
creased upon HSV infection, possibly due to activation of
Rho GTPase signaling during virus attachment to cells. Flu-
orescence imaging revealed that HSPG expression is higher
along the filopodial structures. This mode of attachment
has also been reported for vaccinia virus, human papilloma
virus type 16, hepatitis C virus, and human immunodefi-
ciency virus (HIV) [35].
ii. Entry: After the initial attachment to the cell surface,
virus entry is the next step in the lifecycle. Various modes
of viral entry have been established. The virus is taken into
the cells by either direct fusion with the plasma membrane,
which is independent of pH change, or through endocytosis
mediated by specific cellular receptors. The glycoprotein D
(gD) on HSV plays an important role in both of the afore-
mentioned uptake processes and glycoproteins H and L (gH
and gL) act in concert to complete the fusion machinery. To
date the following receptors have been identified for gD:
herpes virus entry mediator (HVEM), nectin-1 and -2 and 3-
O sulfated heparan sulfate (3-OS HS) [21]. HVEM was the
first identified HSV receptor that belongs to the tumor ne-
crosis factor (TNF) superfamily. The next set of receptors
identified is represented by nectin-1 and -2. They belong to
the immunoglobulin superfamily. The last receptor is a rare
modification of the large sugar molecule HS mediated by
the 3-O-sulfotransferase 3 (3-OST-3). 3-OST-3 belongs to
the family of 3-O sulfotransferases (3-OSTs) that place sul-
fate groups at the 3-OH position on the glucosamine in HS.
This specific and rare modification of HS dictates the bio-
logical activity of HS and occurs during the last step of HS
biosynthesis. As an example, modification of HS by 3-OST-1
serves as a binding site for antithrombin, a major player in
anticoagulation [36]. 3-OST-3 modified HS serves as an
entry receptor for HSV and addition of soluble form of 3-OS
HS in HSV resistant cell lines showed increased viral entry
[38, 39]. Interestingly, 3-OST-3 generated receptor fails to
mediate HSV-2 entry but may probably help in the attach-
ment of HSV-2 [19, 38].
Viral entry can occur in the presence of any one of the
aforementioned receptors and absence of all three recep-
tors abolishes viral entry. Even though gD is needed for
receptor-mediated endocytosis and also for the direct fu-
sion of viral envelop to the plasma membrane, there seems
to be no clear consensus on how and which mode of entry
the viruses use in human hosts or animal models. While
entry into some cultured cells like CHO, HeLa and HCEs are
reported to be through receptor mediated endocytosis,
entry into Vero and neuronal cell lines are through direct
fusion with the plasma membrane [39, 40]. In addition to
gD playing a vital role in viral entry, accumulating evidence
also suggests the important role of gB in HSV entry as a gB
null virus was unable to enter and cause infection in target
cells [41]. Paired immunoglobulin-like type 2 receptor α
(PILRα) has been shown to associate with gB to function as
a co-receptor in aiding HSV-1 entry. Mutations on the sites
where gB attaches to PILRα not only reduced viral entry
but also reduced viral replication and neuroinvasiveness
[42-44]. Furthermore, another protein that belongs to the
sialic acid-binding Ig-like lectin family which shares a simi-
lar homology to PILRα called the myelin-associated glyco-
protein (MAG) acts as a co-receptor for HSV-1 entry when
expressed exogenously [45]. Another co-receptor called
non-muscle myosin IIA (NMIIA) was also identified to bind
gB on the cell surface and aide in the viral entry [46]. As an
actin binding motor protein, NM-IIA plays a critical role in
cell adhesion and migration. The glycoproteins gH and gL
together with gB and gD form the fusion complex [47, 48].
gH exists as a hetero-oligomeric complex with gL. This
D. Jaishankar and D.Shukla (2016) Genital Herpes and STI
OPEN ACCESS
| www.microbialcell.com 441 Microbial Cell | SEPTEMBER 2016 | Vol. 3 No. 9
complex is essential for the processing and cell surface
expression of gH [49, 50] and is conserved in many of the
herpesviruses [51]. Apart from playing a role in the fusion
machinery, the gH/gL complex plays a role in virus entry by
interacting with various cell surface proteins [52], integrins
being the most common. Interaction of gH with integrin
αvβ3 facilitates HSV-2 viral entry and calcium signaling in
human genital tract epithelial cells [53]. Another study
shows that αvβ6 and αvβ8 serve as interchangeable recep-
tors for gH/gL that promote endocytosis and activation of
membrane fusion [54]. A recent study by the same group
also found that conformational changes in the above men-
tioned integrin receptors are essential to promote the dis-
sociation of gL from the gH/gL complex, a proposed new
mechanism in HSV viral entry [55].
Other alternative modes of viral entry have also been
identified. A phagocytosis-like uptake of the virus particles
was reported to be observed once the virus particles have
attached to the filopodia; it is believed to exhibit mixed
traits of endocytosis and phagocytosis [56]. Cytoskeleton
rearrangement and their associated cellular signaling
pathways have also been implicated in facilitating HSV en-
try into cells [57]. Rho-GTPase signaling pathway involving
Rho-A and cdc42, key modulators in the formation of filo-
podia, were shown to be activated and aide in the phago-
cytic-like uptake of the virus [56]. Another signaling path-
way called phosphoinositide 3 kinase (PI3K) pathway,
which is involved in the downstream of the filopodial for-
mation, was also found to affect multiple steps in the HSV
entry [58]. This same pathway is also implicated to control
the activity of cofilin, a family of actin-binding proteins, in
facilitating entry of virus into neuronal cells [59]. The acti-
vation of Akt signaling in triggering calcium release which
aids in HSV viral entry has also been shown [60].
iii. Capsid Transport and Replication: Upon successful
entry into cells, the viral capsid and tegument proteins are
released into the cytoplasm. The virion host shutoff protein
(vhs) is a viral tegument protein that is released into the
cytoplasm after entry and degrades host mRNAs that regu-
late stress response. The capsid then translocates to the
nucleus along microtubules via the dynein and dynactin
motor proteins and releases the viral DNA into the nucleo-
plasm [61-63]. A recent study reported the role of heat-
shock protein 90 (Hsp90) to be involved with HSV capsid
transport to the nucleus via interaction with acetylated α-
tubulin [64]. The uncoating of viral DNA occurs at the nu-
clear pore.
iv. Replication and Assembly: Once inside the nucleus,
several viral genes are expressed in an ordered fashion.
The proteins of the α genes or intermediate early (IE)
genes are the first to be transcribed. The products of these
genes are termed as infected cell protein (ICP) and there
are five ICPs: 0, 4, 22, 27 and 47. The virus encodes a teg-
ument protein: VP16 that aids in the transcription of the α
genes. The expression of ICP4 is then thought to drive the
expression of the β genes or the early genes. The β genes
encode for various proteins that promote viral DNA repli-
cation, including the enzyme thymidine kinase (TK). The
virus utilizes TK for replication leading to the expression of
the γ or late genes. The proteins of the γ genes encode for
several components of the viral structure including capsid
and envelop proteins. Various viral components are
formed which then assemble and the viral DNA is repack-
aged into a new capsid. Fully assembled capsid exits from
the nucleus by acquiring a glycoprotein-containing envelop
at the inner nuclear membrane and losing it at the outer
membrane when the naked capsid is released in the cyto-
plasm for re-envelopment using a Golgi-derived membrane
(Fig. 1).
v. Autophagy Modulation during Active Replication:
The role of autophagy, a cellular process involved in main-
taining the metabolic and homeostatic activity, in HSV rep-
lication has been widely studied. The ICP34.5 protein, a
neurovirulence factor, regulates the replication of HSV by
controlling the autophagic pathway via inhibition of either
PKR/eIF2a signaling pathway [65, 66] or beclin-1, a protein
involved in the formation of autophagosomes [67]. A re-
cent study showed that a basal level of autophagy is need-
ed for efficient replication of virus and disrupting the basal
level would lead to reduced viral titers [68]. Another recent
study showed the role of a host cytoplasmic protein called
axin in controlling autophagy and HSV replication [69]. The
results from this study indicate that axin expression reduc-
es the levels of cellular autophagy induced by HSV, result-
ing in enhanced HSV replication.
vi. Latency and Reactivation: One of the key traits of
this family of viruses is to go latent for the life of the host
after primary infection. How and why the virus goes latent
is only partially understood and is one of the hot topics in
herpes research. After a lytic infection the virus has the
ability to evade and mask itself from the host defense.
Latency is established when the virus migrates to the sen-
sory ganglia via a retrograde fashion and invades the nu-
cleus of the neurons (Fig. 2). In the nucleus the HSV ge-
nome is maintained in a circular form and remains in a
silent state. During this state, a region of the genome that
encodes for the latency associated transcripts (LATs) re-
mains active [70]. Kramer et al. also showed the presence
of HSV transcripts using RT-PCR analyses in latently infect-
ed mouse ganglia [71, 72]. The exact role and function of
the LATs also remains to be completely understood. How-
ever, research over the last decade has revealed the com-
mon functions of LAT: they help in reducing the expression
of the viral genome thereby maintaining them in a latent
state protected from the immune system [73] and they
protect infected neurons from apoptosis, thus increasing
the amount of latent transcripts that would eventually
increase the viral load upon reactivation [74, 75]. In addi-
tion, the host immune system has also been implicated to
play a vital role in viral latency. Studies in the mouse mod-
els of latent HSV infection revealed the presence of infil-
trating immune cells and cytokines in latently infected gan-
glia [76-78] while some suggest that the presence of low
viral transcript levels could lead to a local milieu of immune
effectors that could repress HSV gene expression [79, 80].
Some evidence also suggests the role of neuronal functio in
maintaining latency [81-83]. Furthermore, during latent
infection, the ability of some parts of the HSV genome to
D. Jaishankar and D.Shukla (2016) Genital Herpes and STI
OPEN ACCESS
| www.microbialcell.com 442 Microbial Cell | SEPTEMBER 2016 | Vol. 3 No. 9
remain transcriptionally active and inactive suggested the
presence of epigenetic control. Two studies that used
computational analysis and latently infected mice revealed
that DNA methylation, a most common epigenetic mecha-
nism, did not regulate HSV latent gene expression [84, 85],
leading to the investigation of other epigenetic mecha-
nisms.
The role of chromatin and HSV latency has gained in-
creasing popularity as the HSV DNA is devoid of histones
[86] but upon infection gets assembled into the nucleo-
some [87] and associates with histones [88]. However
whether heterochromatin or euchromatin play a role in
HSV latency was not known. Only recently, using various
molecular techniques, the presence of heterochromatin or
euchromatin in HSV-infected cells has been studied to pro-
vide a basis for a chromatin-based epigenetic mechanism
of HSV gene regulation in different cell types [89]. In a
study by Kubat et al., their findings showed that active
chromatin was associated with LAT gene as increasing lev-
els of acetylated H3 histone were found to be associated
with the LAT promoter and enhancer compared with the
ICP0 gene [90]. In another study by Wang et al., it was
shown that as latent infection is established the HSV lytic
genes are progressively associated with chromatin that
contains dimethylation of H3K9me2, which is an indicator
of heterochromatin [91]. Thus there is a general notion
that during latent infection the LAT gene is associated with
euchromatin whereas the lytic genes are associated with
heterochromatin. The study by Amelio et al. gave insights
into how and why different chromatin are maintained and
regulated separately on the latent viral genome [92]. Their
study identified candidate insulator elements, DNA se-
quences that bind protein factors that maintain chromatin
boundaries. These contain CCCTC sites that are bound by
the CCCTC-binding factor (CTCF) upstream of the LAT pro-
moter boundary and in the LAT intron. They proposed that
insulators keep the LAT euchromatin activity within a
boundary and heterochromatin outside of the same
boundary.
Reactivation of the latent virus occurs when an external
stimuli or ‘stress’ is applied to the neuron. Various factors
such as environmental conditions, fever, exposure to sun-
light and other unknown conditions have been attributed
to cause reactivation but their exact targets at the molecu-
lar level remain unknown. When the virus reactivates it
travels from the sensory ganglia via anti-retrograde fashion
to the primary infection site or sites of high neuron inner-
vations where active virus replication and shedding occur
and symptoms like pain, inflammation and lesions develop.
In an effort to understand the exact role of LATs in the
Figure 2: Schematic of Primary Infection and Reactivation. Primary infection occurs when a host is exposed to the virus for the first time.
When a person is exposed to HSV, the virus infects the epithelial cells. Depending on the immune system of the host, lytic infection leads to
virus shedding that can cause symptoms such as ulcers or remain asymptomatic. After lytic infection, the virions reach the nerve endings
and through a retrograde transport, reach the sacral ganglion where it establishes latency till the life of the host. Recurrent infections occur
when the virus gets reactivated due to stress, environmental conditions and other unknown factors. Reactivation causes the virus from the
sacral ganglion to travel to the site of primary infection or high nerve endings via an anterograde fashion where virus shedding can cause
symptoms or remain asymptomatic depending on the host immune system.
D. Jaishankar and D.Shukla (2016) Genital Herpes and STI
OPEN ACCESS
| www.microbialcell.com 443 Microbial Cell | SEPTEMBER 2016 | Vol. 3 No. 9
reactivation of HSV, LAT encoded micro RNAs (miRNA)
were discovered. miRNAs are a family of non-coding RNA
that is approximately 22 nucleotides in length. They usually
function at a post-transcription level by inhibiting protein
synthesis via mRNA degradation. HSV miRNAs have been
shown to be expressed during productive infection, which
helps degrade host immune responses as well as during
latency, which helps in establishing latency or helps in re-
activation [93].
vii. Egress: Upon formation of capsid and packaging of
the virus DNA, the virions eventually have to egress or
leave the nucleus and the cell to get into the extracellular
environment. While the process of HSV egress still requires
some clarity due to varying experimental models and com-
plexity in studying the virus-nuclear interactions, the fol-
lowing is the accepted model for viral egress. Budding is
the initial step in the nuclear egress of HSV. In this process
the capsid acquires the envelope from the inner nuclear
membrane and two viral proteins: UL31 and UL34 are re-
ported to be necessary for the budding process [94]. Once
the virus reaches the perinuclear region, it is thought to
lose the primary envelope or undergoes de-envelopment
and evidence suggests that the final assembly of tegument,
envelope and the glycoproteins occur within the cytoplas-
mic compartments (presumably in the Golgi or Endoplas-
mic Reticulum, ER). During productive infection either in
primary infection or after reactivation, for efficient trans-
mission and infection, the virus needs to spread to neigh-
boring cells. The release of the virus from infected cells
requires both host factors and viral components. Among
the viral components, glycoproteins E and I (gE and gI) are
needed for efficient spread of viruses in certain polarized
and non-polarized epithelial cells and neuronal cells [95,
22]. Among the host factors, a HS degrading enzyme: hepa-
ranase (HPSE) has been recently shown to aide in viral
egress [96]. The study shows how the levels of HPSE in-
crease over time with HSV infection as active form of HPSE
is translocated to the plasma membrane of infected cells to
remove HS for smoother release of newly generated viri-
ons. The role of myosin motor proteins such as NMIIA and
myoVa have also been implicated in HSV egress [97, 98].
SYMPTOMS AND PATHOLOGY
Genital herpes is predominantly transmitted through
sexual contact. Viral transmission by oro-genital contact is
mostly HSV-1 and therefore the number of genital HSV-1
cases is on the rise [99-101]. Virus shedding is more pre-
dominant in sites like mouth and mucosal surfaces such as
the vagina. Contact with any one of these increases the risk
of being infected with HSV.
An episode or outbreak is termed as the phase in which
individuals experience symptoms and the severity of these
episodes depends on previous immunity to HSV. Notably,
almost 25% of people presenting with a first clinical epi-
sode of genital herpes have serological evidence of past
HSV-2 infection at the time of presentation, suggesting
initial infection was asymptomatic [102]. In many other
instances of primary infections where the patient encoun-
ters HSV for the first time the first episode may occur any-
where between 2 days to 2 weeks after primary infection.
Primary infections are clinically most severe and most likely
symptomatic [103]. Symptoms like fever, itching and mus-
cle pains usually in the lower part of the body are most
common in primary infection; 40% of men and 70% of
women also report fever, headache, malaise, and myalgias
[104]. Papule formulation followed by a wide distribution
of blisters or lesions appear around the genital areas that
eventually break to form ulcers (Fig. 2). Over a period of
time the ulcers crust and heal. In women common sites for
lesion are the cervix, vagina, labia majora and minora and
perianal region through infected vaginal fluid and in men it
is mostly on the shaft or the glans of the penis. Anal lesions
are also reported in homosexual men. Primary infections
either by HSV-1 or by HSV-2 cannot be differentiated just
by clinical symptoms; additional laboratory testing is need-
ed to differentiate between the two viruses.
At the tissue and molecular level, HSV-2 infects the epi-
thelial cells on the genital mucosa leading to an increase in
inflammatory response and cell death at the site of infec-
tion. Multinucleated cells and syncytia formation are the
most common observation in cells infected with HSV. The
recruitment of macrophages, natural killer cells, B-cell and
T-cell mediated immunity [105, 106] and the release of
cytokines has been reported to play a role in innate and
adaptive immunity to HSV infections. This contributes to a
chronic inflammatory state in genital skin and mucosa.
Histopathologic studies of foreskin in HIV-seronegative
men after adult circumcision have shown a higher concen-
tration of CD4
+
and CD8
+
T-cells in HSV-2–seropositive
compared with HSV-2–seronegative men [107]. During the
course of primary infection, the virus spreads via a retro-
grade fashion along the microtubules lining the axons to
the dorsal root ganglia (DRG) where the neuronal cells act
as reservoirs for the virus to remain latent [108]. Upon
reactivation due to factors such as stress and other un-
known conditions, the virus spreads from the DRG to the
epithelial cells via an anterograde fashion where a lytic
replication of the virus follows, resulting in virus shedding.
This is the cause of recurrent infections and these infec-
tions are usually asymptomatic or may be associated with a
classic genital ulcer. While the innate immune system, spe-
cifically the CD8
+
T-cells and the plasmacytoid dendritic
cells, are attributed in controlling latency and reactivation
of the virus [80, 109, 110], recent reports suggest other-
wise. Studies have shown that CD8α dendritic cells help
drive the establishment of HSV-1 latency [111, 112]. At a
clinical and subclinical level, the severity of viral reactiva-
tion varies widely from person to person and depends on
cell mediated immunity that is considered important for
control of viral replication [113, 114].
DIAGNOSIS
Diagnosis of genital herpes based purely on clinical presen-
tation is often not accurate and could be misleading. Symp-
toms occurring from other bacterial infections like Trepo-
nema pallidum or Haemphilus ducreyi could be confused
D. Jaishankar and D.Shukla (2016) Genital Herpes and STI
OPEN ACCESS
| www.microbialcell.com 444 Microbial Cell | SEPTEMBER 2016 | Vol. 3 No. 9
with HSV resulting in wrong diagnosis [115]. Genital herpes
may also cause atypical symptoms that occur at unusual
sites such as the thighs or the buttocks. HSV-2 is also found
to be a co-factor for HIV-1, which is one of the leading
causes of sexually transmitted infections and at times it
becomes difficult to diagnose the symptoms that occur due
to HIV-1 co-infections [116]. Hence, along with clinical di-
agnosis, laboratory tests are required to accurately diag-
nose genital herpes. To determine the presence of HSV in
laboratory, swabs from the genital lesions are taken and
tested by the following common techniques:
i. Viral culture of HSV has been a gold standard for la-
boratory diagnosis of HSV for the past two decades. Using
the swabs from the genital lesions, the virus can be grown
on tissue culture, usually within 5 days, that is then detect-
ed using immunofluorescence assays or by enzyme immu-
noassay. The limitation with this method is that it lacks
sensitivity as more viruses are usually obtained from pa-
tients with primary infection (80%) but less from patients
with recurrent infections (20-50%) or patients whose le-
sions have begun to heal [117].
ii. Polymerase Chain Reaction (PCR): This method of
nucleic acid amplification has emerged as the next com-
mon method to assess the presence of HSV. Determining
HSV by PCR is faster and four times more sensitive com-
pared to viral culture [118, 119]. Based on this method,
three assays have been approved by the US Food and Drug
Association for the detection of HSV in genital lesions. The-
se include IsoAmp HSV Assay, BioHelix Corporation; Multi-
Code-RTx Herpes Simplex Virus 1 & 2 Kit, EraGen Biosci-
ences, Inc. and BD ProbeTec Herpes Simplex Viruses (HSV I
& 2) QX Amplified DNA Assays, BD Diagnostic Systems.
With increasing technology and advances in kit develop-
ments for HSV detection and typing using PCR, this method
is rapidly replacing the viral culture assay.
iii. Serotyping: This method can not only be used to
detect the presence of HSV but can also be used to
differentiate between genital herpes originating from HSV-
1 or HSV-2. Type-specific IgG against the glycoprotein G
(gG) of HSV-1 and HSV-2 are available that can be used to
distinguish between the two viruses [120]. Serotyping has
another advantage in that it detects the presence of HSV to
confirm if the infection is a primary or recurrent infection.
In primary infection, type-specific HSV antibodies can take
from 2 weeks to 3 months to develop. Therefore, an initial
absence of IgG antibodies specific for gG and subsequent
development of such antibodies after 12 weeks confirms
new HSV infection. Clinicians also recommend this method
to diagnose genital herpes when there are no lesions or
the above mentioned detection tests do not provide
substantial results.
While this review only mentions the above common
techniques to diagnose genital herpes in a laboratory
setting, there are currently other methods and techniques
being developed by research institutes and companies. For
example, LeGoff et al. provide a detailed description of
other available and upcoming diagnostic methods [121].
TREATMENT AND PREVENTION
Genital herpes conditions are primarily treated with antivi-
rals that aim at controlling viral replication. Acyclovir, its
analogue Valacyclovir and Famcyclovir (prodrug of Pency-
clovir) are currently prescribed for genital herpes treat-
ment. These drugs are nucleoside analogues that specifi-
cally inhibit the herpesvirus DNA polymerase. While cyclo-
vir is available in oral and intravenous formulations,
Valacyclovir and Famcyclovir are available only as oral for-
mulations. For primary infections where the symptoms can
be severe, antiviral therapy is usually started even before
the symptoms are confirmed by laboratory diagnosis and
the duration of the therapy is 7-10 days or till the lesions
are healed [122]. In severe cases, to relieve pain, clinicians
recommend the use of analgesics or sitz baths where the
patients’ hips and buttocks are immersed in lukewarm
water [117].
Preventive strategies to efficiently reduce the transmis-
sion of the virus also exist and in combination with the
above mentioned treatments there could probably be a
significant reduction of viral transmission. In the case of
people that have symptomatic viral shedding, the most
common preventive strategy is to abstain from sexual ac-
tivity or to use condoms. A prospective study showed sig-
nificantly lowered levels of viral acquisition among part-
ners that used male condoms [123]. Although it is thought
that female condoms can also reduce virus transmission,
this has not been clinically investigated. Applications of
topical microbicides to prevent genital herpes infections
are also being investigated. This strategy involves the use
of natural or synthetic products that either increase the
natural vaginal defenses or inactivate the HSV virions [124,
125]. A recent study showed that vaginal application of
tenofovir gel, an antiviral microbicide which functions as a
nucleotide reverse-transcriptase inhibitor, reduced the
levels of HSV-2 acquisition among women in South Africa
[5].
Various other therapeutic and prevention strategies
that target different stages of virus lifecycle are currently
being investigated. Peptide therapeutics is fast rising owing
to the ease of synthesis, modifications and their high speci-
ficity [126]. They are being synthesized and used as inhibi-
tors against HSV infections [127]. The TAT (transactivator
of transcription)-peptide, derived from HIV, has been
shown to inhibit infection of HSV in the in vitro and in vivo
models of HSV infections [128, 129]. A study showed the
effect of a synthetic 3-OS HS specific peptide: G2 in block-
ing HSV-2 infections in human cervical (HeLa) cell lines. This
peptide significantly blocked the entry and thereby the
spread of the virus [130] and a D-enantiomer of this pep-
tide exhibits higher stability and more promise in inhibiting
HSV infection [131]. Another study designed synthetic pep-
tides specific to the glycoproteins gD and gG and showed
that these peptides can effectively recognize HSV-2 anti-
bodies and hence may be used for serodiagnostic assays
[132]. Because HSV utilizes the cytoskeleton filaments and
kinases during its entry, a recent study showed that block-
ing the myosin light chain kinase (MLCK) with inhibitors
D. Jaishankar and D.Shukla (2016) Genital Herpes and STI
OPEN ACCESS
| www.microbialcell.com 445 Microbial Cell | SEPTEMBER 2016 | Vol. 3 No. 9
such as blebbistatin significantly reduces HSV infection
[133], providing new evidence for potential targets in
blocking HSV infections. The advent of nanoparticles in
drug delivery was successful, owing to their ability to pro-
vide sustained or extended delivery of drugs at a local site.
Nanoparticles or nanoparticle compositions to protect
against HSV-2 infections are also being actively researched.
Zinc Oxide (ZnO) nanoparticles exhibited significant antivi-
ral activity in both the in vitro model using vaginal epitheli-
al cells and the in vivo mice model of HSV-2 infections
[134]. Three different modes of treatment were used in
this study: prophylaxis, therapeutic and neutralization. In
all the three modes of treatment, the ZnO nanoparticles
showed promising results in blocking HSV-2 infections.
Another study showed the potential antiviral use of mucus-
penetrating nanoparticles [135]. In this study, acyclovir
monophosphate loaded mucus-penetrating nanoparticles
showed an increase in drug retention and distribution
thereby providing an effective protection against HSV-2
challenge.
Protection against genital herpes infections can be en-
hanced by induction of protective immune responses using
vaccines. Vaccines against genital herpes are underway
and in the majority of clinical trials only prophylactic vac-
cines have seen success so far. There have been no reports
of any therapeutic vaccines that show promise against
genital herpes infections. These vaccines consist of subu-
nits of glycoproteins such as gD or gB. A gD2 subunit vac-
cine, when administered with alum as adjuvant, showed
around 39-46% efficacy in preventing HSV-2 infections in
patients that were seronegative for HSV-1 and HSV-2 but
did not provide protection to patients that were seroposi-
tive for HSV-1 [136, 137]. Other viral glycoproteins such as
gC and gE are also being used as vaccines to study their
effectivity in blocking genital herpes infections [138, 139].
Peptide based vaccines are also being developed to incite
immune responses against HSV-2 infections. A study de-
veloped a peptide based vaccine: HerpV, which generates
CD4
+
and CD8
+
responses when subjected to HSV-2 chal-
lenge [140, 141].
CONCLUSION AND FUTURE DIRECTIONS
There is no doubt that our understanding of HSV-2 lifecycle
and associated pathogenesis has improved dramatically
over the last several years but challenges remain in many
areas, especially those relating to disease management
and prevention. The new knowledge has provided a major
opportunity to develop new strategies for patient care by
combining our understanding of viral infection mechanisms,
host immune responses, and the viral mechanisms that
subvert them. New anti-HSV drugs are on the horizon,
many of which may target other herpesviruses as well. At
present, the development of vaccines against HSV-2 is a
highly active area of research and many innovative
strategies are currently being tested for an effective
vaccine generation. Future clinical trials will see many new,
non-nucleoside anti-herpetic drug candidates as well as
many newer approaches, including immune-based
therapeutics. An area that needs extra attention is rapid
diagnostics, especially since genital herpes can be caused
by both HSV-1 and HSV-2. Therefore quick and easily
available tests can yield much better results in reducing
symptoms and lowering transmission rate. Any success in
reducing transmission rate will mean a step closer to the
greatest challenge for herpes virologists, which is complete
elimination of this lifelong infection.
ACKNOWLEDGMENTS
This work is supported by a NIH grant (AI103754) to D.S.
CONFLICT OF INTEREST
The authors declare no conflict of interest.
COPYRIGHT
© 2016 Jaishankar and Shukla. This is an open-access arti-
cle released under the terms of the Creative Commons
Attribution (CC BY) license, which allows the unrestricted
use, distribution, and reproduction in any medium, provid-
ed the original author and source are acknowledged.
Please cite this article as: Dinesh Jaishankar and Deepak Shukla
(2016). Genital Herpes: Insights on a Sexually Transmitted Infec-
tious Disease. Microbial Cell 3(9): 438-450. doi:
10.15698/mic2016.09.528
REFERENCES
1. Wald A (2006). Genital HSV‐1 infections. Sex Transm Infect 82(3):
189–190.
2. Felman YM and Nikitas JA (1983). Sexually transmitted diseases and
child sexual abuse. Part II. N Y State J Med 83(5): 714–716.
3. Kinghorn GR (1993). Genital herpes: natural history and treatment
of acute episodes. J Med Virol Suppl 1: 33–38.
4. Abdool Karim SS, Abdool Karim Q, Kharsany ABM, Baxter C, Grobler
AC, Werner L, Kashuba A, Mansoor LE, Samsunder N, Mindel A, and
Gengiah TN (2015). Tenofovir Gel for the Prevention of Herpes Sim-
plex Virus Type 2 Infection. N Engl J Med 373(6): 530–539.
5. Wald A and Corey L (2007). Persistence in the population: epidemi-
ology, transmission. In: Arvin A, Campadelli-Fiume G, Mocarski E,
Moore PS, Roizman B, Whitley R, Yamanishi K, editors. Human Her-
pesviruses: Biology, Therapy, and Immunoprophylaxis. Cambridge
University Press, Cambridge.
http://www.ncbi.nlm.nih.gov/books/NBK47447/.
6. Xu F, Schillinger JA, Sternberg MR, Johnson RE, Lee FK, Nahmias AJ,
and Markowitz LE (2002). Seroprevalence and Coinfection with Herpes
Simplex Virus Type 1 and Type 2 in the United States, 1988–1994. J
Infect Dis 185(8): 1019–1024.
D. Jaishankar and D.Shukla (2016) Genital Herpes and STI
OPEN ACCESS
| www.microbialcell.com 446 Microbial Cell | SEPTEMBER 2016 | Vol. 3 No. 9
7. Huengsberg M (2000). Sexually Transmitted Diseases. Sex Transm
Infect 76(6): 498–498.
8. Halpern-Felsher BL, Cornell JL, Kropp RY, and Tschann JM (2005).
Oral versus vaginal sex among adolescents: perceptions, attitudes,
and behavior. Pediatrics 115(4): 845–851.
9. Roberts CM, Pfister JR, and Spear SJ (2003). Increasing proportion of
herpes simplex virus type 1 as a cause of genital herpes infection in
college students. Sex Transm Dis 30(10): 797–800.
10. Scoular A, Norrie J, Gillespie G, Mir N, and Carman WF (2002).
Longitudinal study of genital infection by herpes simplex virus type 1
in western Scotland over 15 years. BMJ 324(7350): 1366–1367.
11. Manavi K, McMillan A, and Ogilvie M (2004). Herpes simplex virus
type 1 remains the principal cause of initial anogenital herpes in Edin-
burgh, Scotland. Sex Transm Dis 31(5): 322–324.
12. Buxbaum S, Geers M, Gross G, Schofer H, Rabenau HF, and Doerr
HW (2003). Epidemiology of herpes simplex virus types 1 and 2 in
Germany: what has changed? Med Microbiol Immunol (Berl) 192(3):
177–181.
13. Morbidity and Mortality Weekly Report: MMWR (2010). U.S. De-
partment of Health, Education, and Welfare, Public Health Service,
Center for Disease Control.
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5915a3.htm.
14. Malkin J-E (2004). Epidemiology of genital herpes simplex virus
infection in developed countries. Herpes J IHMF 11 Suppl 1: 2A – 23A.
15. Xu F, Sternberg MR, Kottiri BJ, McQuillan GM, Lee FK, Nahmias AJ,
Berman SM, and Markowitz LE (2006). Trends in herpes simplex virus
type 1 and type 2 seroprevalence in the United States. JAMA 296(8):
964–973.
16. Weiss HA, Buve A, Robinson NJ, Van Dyck E, Kahindo M, Anagonou
S, Musonda R, Zekeng L, Morison L, Carael M, Laga M, and Hayes RJ
(2001). The epidemiology of HSV-2 infection and its association with
HIV infection in four urban African populations. AIDS Lond Engl 15
Suppl 4: S97–S108.
17. Weiss H (2004). Epidemiology of herpes simplex virus type 2 infec-
tion in the developing world. Herpes J IHMF 11 Suppl 1: 24A – 35A.
18. Watson-Jones D, Weiss HA, Rusizoka M, Baisley K, Mugeye K,
Changalucha J, Everett D, Balira R, Knight L, Ross D, and Hayes RJ
(2007). Risk factors for herpes simplex virus type 2 and HIV among
women at high risk in northwestern Tanzania: preparing for an HSV-2
intervention trial. J Acquir Immune Defic Syndr 46(5): 631–642.
19. Shukla D and Spear PG (2001). Herpesviruses and heparan sulfate:
an intimate relationship in aid of viral entry. J Clin Invest 108(4): 503–
510.
20. Herold BC, WuDunn D, Soltys N, and Spear PG (1991). Glycopro-
tein C of herpes simplex virus type 1 plays a principal role in the ad-
sorption of virus to cells and in infectivity. J Virol 65(3): 1090–1098.
21. Spear PG, Eisenberg RJ, and Cohen GH (2000). Three classes of cell
surface receptors for alphaherpesvirus entry. Virology 275(1): 1–8.
22. Dingwell KS and Johnson DC (1998). The Herpes Simplex Virus gE-
gI Complex Facilitates Cell-to-Cell Spread and Binds to Components of
Cell Junctions. J Virol 72(11): 8933–8942.
23. Weissenhorn W, Hinz A, and Gaudin Y (2007). Virus membrane
fusion. Membr Traffick 581(11): 2150–2155.
24. Friedman HM, Cohen GH, Eisenberg RJ, Seidel CA, and Cines DB
(1984). Glycoprotein C of herpes simplex virus 1 acts as a receptor for
the C3b complement component on infected cells. Nature 309(5969):
633–635.
25. Baucke RB and Spear PG (1979). Membrane proteins specified by
herpes simplex viruses. V. Identification of an Fc-binding glycoprotein.
J Virol 32(3): 779–789.
26. Johnson DC and Feenstra V (1987). Identification of a novel herpes
simplex virus type 1-induced glycoprotein which complexes with gE
and binds immunoglobulin. J Virol 61(7): 2208–2216.
27. Johnson DC, Frame MC, Ligas MW, Cross AM, and Stow ND (1988).
Herpes simplex virus immunoglobulin G Fc receptor activity depends
on a complex of two viral glycoproteins, gE and gI. J Virol 62(4): 1347–
1354.
28. David AT, Baghian A, Foster TP, Chouljenko VN, and Kousoulas KG
(2008). The herpes simplex virus type 1 (HSV-1) glycoprotein K(gK) is
essential for viral corneal spread and neuroinvasiveness. Curr Eye Res
33(5): 455–467.
29. Hutchinson L and Johnson DC (1995). Herpes simplex virus glyco-
protein K promotes egress of virus particles. J Virol 69(9): 5401–5413.
30. Kim I-J, Chouljenko VN, Walker JD, and Kousoulas KG (2013). Her-
pes simplex virus 1 glycoprotein M and the membrane-associated
protein UL11 are required for virus-induced cell fusion and efficient
virus entry. J Virol 87(14): 8029–8037.
31. Baines JD, Wills E, Jacob RJ, Pennington J, and Roizman B (2007).
Glycoprotein M of Herpes Simplex Virus 1 Is Incorporated into Virions
during Budding at the Inner Nuclear Membrane. J Virol 81(2): 800–
812.
32. Lau KS-Y and Crump MC (2015). HSV-1 gM and the gK/pUL20
Complex Are Important for the Localization of gD and gH/L to Viral
Assembly Sites. Viruses 7(3).
33. Herold BC, Visalli RJ, Susmarski N, Brandt CR, and Spear PG (1994).
Glycoprotein C-independent binding of herpes simplex virus to cells
requires cell surface heparan sulphate and glycoprotein B. J Gen Virol
75 ( Pt 6): 1211–1222.
34. Oh M-J, Akhtar J, Desai P, and Shukla D (2010). A role for heparan
sulfate in viral surfing. Biochem Biophys Res Commun 391(1): 176–
181.
35. Spear M and Wu Y (2014). Viral exploitation of actin: force-
generation and scaffolding functions in viral infection. Virol Sin 29(3):
139–147.
36. Liu J and Pedersen LC (2007). Anticoagulant heparan sulfate: struc-
tural specificity and biosynthesis. Appl Microbiol Biotechnol 74(2):
263–272.
37. Shukla D, Liu J, Blaiklock P, Shworak NW, Bai X, Esko JD, Cohen GH,
Eisenberg RJ, Rosenberg RD, and Spear PG (1999). A novel role for 3-
O-sulfated heparan sulfate in herpes simplex virus 1 entry. Cell 99(1):
13–22.
38. Tiwari V, O’donnell C, Copeland RJ, Scarlett T, Liu J, and Shukla D
(2007). Soluble 3-O-sulfated heparan sulfate can trigger herpes sim-
plex virus type 1 entry into resistant Chinese hamster ovary (CHO-K1)
cells. J Gen Virol 88(Pt 4): 1075–1079.
39. Nicola AV, Hou J, Major EO, and Straus SE (2005). Herpes simplex
virus type 1 enters human epidermal keratinocytes, but not neurons,
via a pH-dependent endocytic pathway. J Virol 79(12): 7609–7616.
40. Nicola AV, McEvoy AM, and Straus SE (2003). Roles for endocytosis
and low pH in herpes simplex virus entry into HeLa and Chinese ham-
ster ovary cells. J Virol 77(9): 5324–5332.
41. Cai WZ, Person S, Warner SC, Zhou JH, and DeLuca NA (1987).
Linker-insertion nonsense and restriction-site deletion mutations of
the gB glycoprotein gene of herpes simplex virus type 1. J Virol 61(3):
714–721..
D. Jaishankar and D.Shukla (2016) Genital Herpes and STI
OPEN ACCESS
| www.microbialcell.com 447 Microbial Cell | SEPTEMBER 2016 | Vol. 3 No. 9
42. Satoh T, Arii J, Suenaga T, Wang J, Kogure A, Uehori J, Arase N,
Shiratori I, Tanaka S, Kawaguchi Y, Spear PG, Lanier LL, and Arase H
(2008). PILRalpha is a herpes simplex virus-1 entry coreceptor that
associates with glycoprotein B. Cell 132(6): 935–944.
43. Arii J, Wang J, Morimoto T, Suenaga T, Akashi H, Arase H, and
Kawaguchi Y (2010). A single-amino-acid substitution in herpes sim-
plex virus 1 envelope glycoprotein B at a site required for binding to
the paired immunoglobulin-like type 2 receptor alpha (PILRalpha)
abrogates PILRalpha-dependent viral entry and reduces pathogenesis.
J Virol 84(20): 10773–10783.
44. Wang J, Fan Q, Satoh T, Arii J, Lanier LL, Spear PG, Kawaguchi Y,
and Arase H (2009). Binding of herpes simplex virus glycoprotein B
(gB) to paired immunoglobulin-like type 2 receptor alpha depends on
specific sialylated O-linked glycans on gB. J Virol 83(24): 13042–13045.
45. Suenaga T, Satoh T, Somboonthum P, Kawaguchi Y, Mori Y, and
Arase H (2010). Myelin-associated glycoprotein mediates membrane
fusion and entry of neurotropic herpesviruses. Proc Natl Acad Sci USA
107(2): 866–871.
46. Arii J, Goto H, Suenaga T, Oyama M, Kozuka-Hata H, Imai T, Mi-
nowa A, Akashi H, Arase H, Kawaoka Y, and Kawaguchi Y (2010). Non-
muscle myosin IIA is a functional entry receptor for herpes simplex
virus-1. Nature 467(7317): 859–862.
47 Handler CG, Eisenberg RJ, and Cohen GH (1996). Oligomeric struc-
ture of glycoproteins in herpes simplex virus type 1. J Virol 70(9):
6067–6070.
48. Handler CG, Cohen GH, and Eisenberg RJ (1996). Cross-linking of
glycoprotein oligomers during herpes simplex virus type 1 entry. J
Virol 70(9): 6076–6082.
49. Roop C, Hutchinson L, and Johnson DC (1993). A mutant herpes
simplex virus type 1 unable to express glycoprotein L cannot enter
cells, and its particles lack glycoprotein H. J Virol 67(4): 2285–2297.
50. Hutchinson L, Browne H, Wargent V, Davis-Poynter N, Primorac S,
Goldsmith K, Minson AC, and Johnson DC (1992). A novel herpes sim-
plex virus glycoprotein, gL, forms a complex with glycoprotein H (gH)
and affects normal folding and surface expression of gH. J Virol 66(4):
2240–2250.
51. Browne H, Baxter V, and Minson T (1993). Analysis of protective
immune responses to the glycoprotein H-glycoprotein L complex of
herpes simplex virus type 1. J Gen Virol 74(12): 2813–2817.
52. Gianni T, Cerretani A, Dubois R, Salvioli S, Blystone SS, Rey F, and
Campadelli-Fiume G (2010). Herpes simplex virus glycoproteins H/L
bind to cells independently of {alpha}V{beta}3 integrin and inhibit
virus entry, and their constitutive expression restricts infection. J Virol
84(8): 4013–4025.
53. Cheshenko N, Trepanier JB, Gonzalez PA, Eugenin EA, Jacobs WRJ,
and Herold BC (2014). Herpes simplex virus type 2 glycoprotein H
interacts with integrin alphavbeta3 to facilitate viral entry and calcium
signaling in human genital tract epithelial cells. J Virol 88(17): 10026–
10038.
54. Gianni T, Salvioli S, Chesnokova LS, Hutt-Fletcher LM, and Campa-
delli-Fiume G (2013). αvβ6- and αvβ8-Integrins Serve As Interchange-
able Receptors for HSV gH/gL to Promote Endocytosis and Activation
of Membrane Fusion. PLoS Pathog 9(12): e1003806.
55. Gianni T, Massaro R, and Campadelli-Fiume G (2015). Dissociation
of HSV gL from gH by alphavbeta6- or alphavbeta8-integrin promotes
gH activation and virus entry. Proc Natl Acad Sci USA 112(29): E3901–
E3910.
56. Clement C, Tiwari V, Scanlan PM, Valyi-Nagy T, Yue BYJT, and
Shukla D (2006). A novel role for phagocytosis-like uptake in herpes
simplex virus entry. J Cell Biol 174(7): 1009–1021.
57. Akhtar J and Shukla D (2009). Viral entry mechanisms: cellular and
viral mediators of herpes simplex virus entry. FEBS J 276(24): 7228–
7236.
58. Tiwari V and Shukla D (2010). Phosphoinositide 3 kinase signalling
may affect multiple steps during herpes simplex virus type-1 entry. J
Gen Virol 91(Pt 12): 3002–3009.
59. Zheng K, Xiang Y, Wang X, Wang Q, Zhong M, Wang S, Wang X, Fan
J, Kitazato K, and Wang Y (2014). Epidermal Growth Factor Receptor-
PI3K Signaling Controls Cofilin Activity To Facilitate Herpes Simplex
Virus 1 Entry into Neuronal Cells. mBio 5(1): e00958-13.
60. Cheshenko N, Trepanier JB, Stefanidou M, Buckley N, Gonzalez P,
Jacobs W, and Herold BC (2013). HSV activates Akt to trigger calcium
release and promote viral entry: novel candidate target for treatment
and suppression. FASEB J Off Publ Fed Am Soc Exp Biol 27(7): 2584–
2599.
61. Dohner K, Wolfstein A, Prank U, Echeverri C, Dujardin D, Vallee R,
and Sodeik B (2002). Function of dynein and dynactin in herpes sim-
plex virus capsid transport. Mol Biol Cell 13(8): 2795–2809.
62. Radtke K, Kieneke D, Wolfstein A, Michael K, Steffen W, Scholz T,
Karger A, and Sodeik B (2010). Plus- and Minus-End Directed Microtu-
bule Motors Bind Simultaneously to Herpes Simplex Virus Capsids
Using Different Inner Tegument Structures. PLoS Pathog 6(7):
e1000991.
63. Sodeik B, Ebersold MW, and Helenius A (1997). Microtubule-
mediated transport of incoming herpes simplex virus 1 capsids to the
nucleus. J Cell Biol 136(5): 1007–1021.
64. Zhong M, Zheng K, Chen M, Xiang Y, Jin F, Ma K, Qiu X, Wang Q,
Peng T, Kitazato K, and Wang Y (2014). Heat-Shock Protein 90 Pro-
motes Nuclear Transport of Herpes Simplex Virus 1 Capsid Protein by
Interacting with Acetylated Tubulin. PLoS ONE 9(6): e99425.
65. He B, Gross M, and Roizman B (1997). The gamma(1)34.5 protein
of herpes simplex virus 1 complexes with protein phosphatase 1alpha
to dephosphorylate the alpha subunit of the eukaryotic translation
initiation factor 2 and preclude the shutoff of protein synthesis by
double-stranded RNA-activated protein kinase. Proc Natl Acad Sci
USA 94(3): 843–848.
66. Talloczy Z, Virgin HW 4th, and Levine B (2006). PKR-dependent
autophagic degradation of herpes simplex virus type 1. Autophagy
2(1): 24–29.
67. Orvedahl A, Alexander D, Talloczy Z, Sun Q, Wei Y, Zhang W, Burns
D, Leib DA, and Levine B (2007). HSV-1 ICP34.5 confers neurovirulence
by targeting the Beclin 1 autophagy protein. Cell Host Microbe 1(1):
23–35.
68. Yakoub AM and Shukla D (2015). Basal Autophagy Is Required for
Herpes simplex Virus-2 Infection. Sci Rep 5: 12985.
69. Choi E-J and Kee S-H (2014). Axin expression delays herpes simplex
virus-induced autophagy and enhances viral replication in L929 cells.
Microbiol Immunol 58(2): 103–111.
70. Roizman B and Whitley RJ (2013). An inquiry into the molecular
basis of HSV latency and reactivation. Annu Rev Microbiol 67: 355–
374.
71. Kramer MF, Chen SH, Knipe DM, and Coen DM (1998). Accumula-
tion of viral transcripts and DNA during establishment of latency by
herpes simplex virus. J Virol 72(2): 1177–1185.
72. Kramer MF and Coen DM (1995). Quantification of transcripts
from the ICP4 and thymidine kinase genes in mouse ganglia latently
infected with herpes simplex virus. J Virol 69(3): 1389–1399.
73. Kent JR, Kang W, Miller CG, and Fraser NW (2003). Herpes simplex
virus latency-associated transcript gene function. J Neurovirol 9(3):
285–290.
D. Jaishankar and D.Shukla (2016) Genital Herpes and STI
OPEN ACCESS
| www.microbialcell.com 448 Microbial Cell | SEPTEMBER 2016 | Vol. 3 No. 9
74. Perng GC, Jones C, Ciacci-Zanella J, Stone M, Henderson G, Yukht
A, Slanina SM, Hofman FM, Ghiasi H, Nesburn AB, and Wechsler SL
(2000). Virus-induced neuronal apoptosis blocked by the herpes sim-
plex virus latency-associated transcript. Science 287(5457): 1500–
1503.
75. Bloom DC (2004). HSV LAT and neuronal survival. Int Rev Immunol
23(1-2): 187–198.
76. Shimeld C, Whiteland JL, Nicholls SM, Grinfeld E, Easty DL, Gao H,
and Hill TJ (1995). Immune cell infiltration and persistence in the
mouse trigeminal ganglion after infection of the cornea with herpes
simplex virus type 1. J Neuroimmunol 61(1): 7–16.
77. Halford WP, Gebhardt BM, and Carr DJ (1996). Persistent cytokine
expression in trigeminal ganglion latently infected with herpes simplex
virus type 1. J Immunol 157(8): 3542–3549..
78. Liu T, Tang Q, and Hendricks RL (1996). Inflammatory infiltration of
the trigeminal ganglion after herpes simplex virus type 1 corneal infec-
tion. J Virol 70(1): 264–271..
79. Chen SH, Garber DA, Schaffer PA, Knipe DM, and Coen DM (2000).
Persistent elevated expression of cytokine transcripts in ganglia la-
tently infected with herpes simplex virus in the absence of ganglionic
replication or reactivation. Virology 278(1): 207–216.
80. Liu T, Khanna KM, Chen X, Fink DJ, and Hendricks RL (2000). CD8(+)
T cells can block herpes simplex virus type 1 (HSV-1) reactivation from
latency in sensory neurons. J Exp Med 191(9): 1459–1466.
81. Wilcox CL and Johnson EM (1987). Nerve growth factor depriva-
tion results in the reactivation of latent herpes simplex virus in vitro. J
Virol 61(7): 2311–2315..
82. Hill JM, Garza HHJ, Helmy MF, Cook SD, Osborne PA, Johnson EMJ,
Thompson HW, Green LC, O’Callaghan RJ, and Gebhardt BM (1997).
Nerve growth factor antibody stimulates reactivation of ocular herpes
simplex virus type 1 in latently infected rabbits. J Neurovirol 3(3):
206–211.
83. Kristie TM, Vogel JL, and Sears AE (1999). Nuclear localization of
the C1 factor (host cell factor) in sensory neurons correlates with
reactivation of herpes simplex virus from latency. Proc Natl Acad Sci
USA 96(4): 1229–1233.
84. Dressler GR, Rock DL, and Fraser NW (1987). Latent herpes simplex
virus type 1 DNA is not extensively methylated in vivo. J Gen Virol 68 (
Pt 6): 1761–1765.
85. Kubat NJ, Tran RK, McAnany P, and Bloom DC (2004). Specific
histone tail modification and not DNA methylation is a determinant of
herpes simplex virus type 1 latent gene expression. J Virol 78(3):
1139–1149.
86. Oh J and Fraser NW (2008). Temporal Association of the Herpes
Simplex Virus Genome with Histone Proteins during a Lytic Infection. J
Virol 82(7): 3530–3537.
87. Deshmane SL and Fraser NW (1989). During latency, herpes sim-
plex virus type 1 DNA is associated with nucleosomes in a chromatin
structure. J Virol 63(2): 943–947.
88. Kent JR, Zeng P-Y, Atanasiu D, Gardner J, Fraser NW, and Berger SL
(2004). During lytic infection herpes simplex virus type 1 is associated
with histones bearing modifications that correlate with active tran-
scription. J Virol 78(18): 10178–10186.
89. Knipe DM and Cliffe A (2008). Chromatin control of herpes simplex
virus lytic and latent infection. Nat Rev Micro 6(3): 211–221.
90. Kubat NJ, Amelio AL, Giordani NV, and Bloom DC (2004). The her-
pes simplex virus type 1 latency-associated transcript (LAT) enhanc-
er/rcr is hyperacetylated during latency independently of LAT tran-
scription. J Virol 78(22): 12508–12518.
91. Wang Q-Y, Zhou C, Johnson KE, Colgrove RC, Coen DM, and Knipe
DM (2005). Herpesviral latency-associated transcript gene promotes
assembly of heterochromatin on viral lytic-gene promoters in latent
infection. Proc Natl Acad Sci USA 102(44): 16055–16059.
92. Amelio AL, McAnany PK, and Bloom DC (2006). A chromatin insula-
tor-like element in the herpes simplex virus type 1 latency-associated
transcript region binds CCCTC-binding factor and displays enhancer-
blocking and silencing activities. J Virol 80(5): 2358–2368.
93. Sun L and Li Q (2012). The miRNAs of herpes simplex virus (HSV).
Virol Sin 27(6): 333–338.
94. Reynolds AE, Ryckman BJ, Baines JD, Zhou Y, Liang L, and Roller RJ
(2001). U(L)31 and U(L)34 Proteins of Herpes Simplex Virus Type 1
Form a Complex That Accumulates at the Nuclear Rim and Is Required
for Envelopment of Nucleocapsids. J Virol 75(18): 8803–8817.
95. Collins WJ and Johnson DC (2003). Herpes simplex virus gE/gI
expressed in epithelial cells interferes with cell-to-cell spread. J Virol
77(4): 2686–2695..
96. Hadigal SR, Agelidis AM, Karasneh GA, Antoine TE, Yakoub AM,
Ramani VC, Djalilian AR, Sanderson RD, and Shukla D (2015). Hepara-
nase is a host enzyme required for herpes simplex virus-1 release from
cells. Nat Commun 6: 6985.
97. van Leeuwen H, Elliott G, and O’Hare P (2002). Evidence of a role
for nonmuscle myosin II in herpes simplex virus type 1 egress. J Virol
76(7): 3471–3481.
98. Roberts KL and Baines JD (2010). Myosin Va enhances secretion of
herpes simplex virus 1 virions and cell surface expression of viral gly-
coproteins. J Virol 84(19): 9889–9896.
99. Lafferty WE, Downey L, Celum C, and Wald A (2000). Herpes sim-
plex virus type 1 as a cause of genital herpes: impact on surveillance
and prevention. J Infect Dis 181(4): 1454–1457.
100. Mertz GJ, Rosenthal SL, and Stanberry LR (2003). Is herpes sim-
plex virus type 1 (HSV-1) now more common than HSV-2 in first epi-
sodes of genital herpes? Sex Transm Dis 30(10): 801–802.
101. Lowhagen GB, Tunback P, Andersson K, Bergstrom T, and Johan-
nisson G (2000). First episodes of genital herpes in a Swedish STD
population: a study of epidemiology and transmission by the use of
herpes simplex virus (HSV) typing and specific serology. Sex Transm
Infect 76(3): 179–182..
102. Bernstein DI, Lovett MA, and Bryson YJ (1984). Serologic analysis
of first-episode nonprimary genital herpes simplex virus infection.
Presence of type 2 antibody in acute serum samples. Am J Med 77(6):
1055–1060.
103. Corey L and Spear PG (1986). Infections with herpes simplex
viruses (1). N Engl J Med 314(11): 686–691.
104. Corey L, Adams HG, Brown ZA, and Holmes KK (1983). Genital
herpes simplex virus infections: clinical manifestations, course, and
complications. Ann Intern Med 98(6): 958–972.
105. Zhu J, Koelle DM, Cao J, Vazquez J, Huang ML, Hladik F, Wald A,
and Corey L (2007). Virus-specific CD8+ T cells accumulate near senso-
ry nerve endings in genital skin during subclinical HSV-2 reactivation. J
Exp Med 204(3): 595–603.
106. Zhu J, Hladik F, Woodward A, Klock A, Peng T, Johnston C, Re-
mington M, Magaret A, Koelle DM, Wald A, and Corey L (2009). Persis-
tence of HIV-1 receptor-positive cells after HSV-2 reactivation is a
potential mechanism for increased HIV-1 acquisition. Nat Med 15(8):
886–892.
107. Johnson KE, Redd AD, Quinn TC, Collinson-Streng AN, Cornish T,
Kong X, Sharma R, Tobian AAR, Tsai B, Sherman ME, Kigozi G, Serwad-
da D, Wawer MJ, and Gray RH (2011). Effects of HIV-1 and herpes
D. Jaishankar and D.Shukla (2016) Genital Herpes and STI
OPEN ACCESS
| www.microbialcell.com 449 Microbial Cell | SEPTEMBER 2016 | Vol. 3 No. 9
simplex virus type 2 infection on lymphocyte and dendritic cell density
in adult foreskins from Rakai, Uganda. J Infect Dis 203(5): 602–609.
108. Cunningham AL, Diefenbach RJ, Miranda-Saksena M, Bosnjak L,
Kim M, Jones C, and Douglas MW (2006). The cycle of human herpes
simplex virus infection: virus transport and immune control. J Infect
Dis 194 Suppl 1: S11–S18.
109. Liu T, Khanna KM, Carriere BN, and Hendricks RL (2001). Gamma
interferon can prevent herpes simplex virus type 1 reactivation from
latency in sensory neurons. J Virol 75(22): 11178–11184.
110. Donaghy H, Bosnjak L, Harman AN, Marsden V, Tyring SK, Meng
T-C, and Cunningham AL (2009). Role for plasmacytoid dendritic cells
in the immune control of recurrent human herpes simplex virus infec-
tion. J Virol 83(4): 1952–1961.
111. Mott KR, Allen SJ, Zandian M, Konda B, Sharifi BG, Jones C,
Wechsler SL, Town T, and Ghiasi H (2014). CD8α Dendritic Cells Drive
Establishment of HSV-1 Latency. PLoS ONE 9(4): e93444.
112. Mott KR, Allen SJ, Zandian M, and Ghiasi H (2014). Coregulatory
interactions among CD8alpha dendritic cells, the latency-associated
transcript, and programmed death 1 contribute to higher levels of
herpes simplex virus 1 latency. J Virol 88(12): 6599–6610.
113. Koelle DM, Chen HB, Gavin MA, Wald A, Kwok WW, and Corey L
(2001). CD8 CTL from genital herpes simplex lesions: recognition of
viral tegument and immediate early proteins and lysis of infected
cutaneous cells. J Immunol 166(6): 4049–4058.
114. Koelle DM, Frank JM, Johnson ML, and Kwok WW (1998). Recog-
nition of herpes simplex virus type 2 tegument proteins by CD4 T cells
infiltrating human genital herpes lesions. J Virol 72(9): 7476–7483.
115. Mackay IM, Harnett G, Jeoffreys N, Bastian I, Sriprakash KS,
Siebert D, and Sloots TP (2006). Detection and discrimination of her-
pes simplex viruses, Haemophilus ducreyi, Treponema pallidum, and
Calymmatobacterium (Klebsiella) granulomatis from genital ulcers.
Clin Infect Dis Off Publ Infect Dis Soc Am 42(10): 1431–1438.
116. Corey L, Wald A, Celum CL, and Quinn TC (2004). The effects of
herpes simplex virus-2 on HIV-1 acquisition and transmission: a review
of two overlapping epidemics. J Acquir Immune Defic Syndr 35(5):
435–445.
117. Gupta R, Warren T, and Wald A (2007). Genital herpes. Lancet
Lond Engl 370(9605): 2127–2137.
118. Ramaswamy M, McDonald C, Smith M, Thomas D, Maxwell S,
Tenant-Flowers M, and Geretti AM (2004). Diagnosis of genital herpes
by real time PCR in routine clinical practice. Sex Transm Infect 80(5):
406–410.
119. Filen F, Strand A, Allard A, Blomberg J, and Herrmann B (2004).
Duplex real-time polymerase chain reaction assay for detection and
quantification of herpes simplex virus type 1 and herpes simplex virus
type 2 in genital and cutaneous lesions. Sex Transm Dis 31(6): 331–
336.
120. Lafferty WE, Krofft S, Remington M, Giddings R, Winter C, Cent A,
and Corey L (1987). Diagnosis of herpes simplex virus by direct immu-
nofluorescence and viral isolation from samples of external genital
lesions in a high-prevalence population. J Clin Microbiol 25(2): 323–
326.
121. LeGoff J, Pere H, and Belec L (2014). Diagnosis of genital herpes
simplex virus infection in the clinical laboratory. Virol J 11: 83.
122. Workowski K (2015). Sexually Transmitted Diseases Treatment
Guidelines, 2015
http://www.cdc.gov/mmwr/preview/mmwrhtml/rr6403a1.htm.
123. Wald A, Langenberg AGM, Krantz E, Douglas JMJ, Handsfield HH,
DiCarlo RP, Adimora AA, Izu AE, Morrow RA, and Corey L (2005). The
relationship between condom use and herpes simplex virus acquisi-
tion. Ann Intern Med 143(10): 707–713.
124. Keller MJ, Tuyama A, Carlucci MJ, and Herold BC (2005). Topical
microbicides for the prevention of genital herpes infection. J Antimi-
crob Chemother 55(4): 420–423.
125. Yang D, Chertov O, and Oppenheim JJ (2001). Participation of
mammalian defensins and cathelicidins in anti-microbial immunity:
receptors and activities of human defensins and cathelicidin (LL-37). J
Leukoc Biol 69(5): 691–697.
126. Lien S and Lowman HB (2003). Therapeutic peptides. Trends
Biotechnol 21(12): 556–562.
127. Galdiero S, Falanga A, Tarallo R, Russo L, Galdiero E, Cantisani M,
Morelli G, and Galdiero M (2013). Peptide inhibitors against herpes
simplex virus infections. J Pept Sci Off Publ Eur Pept Soc 19(3): 148–
158.
128. Jose GG, Larsen IV, Gauger J, Carballo E, Stern R, Brummel R, and
Brandt CR (2013). A Cationic Peptide, TAT-Cd(0), Inhibits Herpes Sim-
plex Virus Type 1 Ocular Infection In Vivo. Invest Ophthalmol Vis Sci
54(2): 1070–1079.
129. Larsen IV and Brandt CR (2010). A Cationic TAT Peptide Inhibits
Herpes Simplex Virus Type 1 Infection of Human Corneal Epithelial
Cells. J Ocul Pharmacol Ther 26(6): 541–547.
130. Ali MM, Karasneh GA, Jarding MJ, Tiwari V, and Shukla D (2012).
A 3-O-sulfated heparan sulfate binding peptide preferentially targets
herpes simplex virus 2-infected cells. J Virol 86(12): 6434–6443.
131. Jaishankar D, Yakoub AM, Bogdanov A, Valyi-Nagy T, and Shukla
D (2015). Characterization of a proteolytically stable D-peptide that
suppresses herpes simplex virus 1 infection: implications for the de-
velopment of entry-based antiviral therapy. J Virol 89(3): 1932–1938.
132. Levi M, Ruden U, Carlberg H, and Wahren B (1999). The use of
peptides from glycoproteins G-2 and D-1 for detecting herpes simplex
virus type 2 and type-common antibodies. J Clin Virol Off Publ Pan
Am Soc Clin Virol 12(3): 243–252.
133. Antoine TE and Shukla D (2014). Inhibition of myosin light chain
kinase can be targeted for the development of new therapies against
herpes simplex virus type-1 infection. Antivir Ther 19(1): 15–29.
134 Antoine TE, Mishra YK, Trigilio J, Tiwari V, Adelung R, and Shukla D
(2012). Prophylactic, therapeutic and neutralizing effects of zinc oxide
tetrapod structures against herpes simplex virus type-2 infection.
Antiviral Res 96(3): 363–375.
135. Ensign LM, Tang BC, Wang Y-Y, Tse TA, Hoen T, Cone R, and
Hanes J (2012). Mucus-penetrating nanoparticles for vaginal drug
delivery protect against herpes simplex virus. Sci Transl Med 4(138):
138ra79.
136. Straus SE, Wald A, Kost RG, McKenzie R, Langenberg AG, Hohman
P, Lekstrom J, Cox E, Nakamura M, Sekulovich R, Izu A, Dekker C, and
Corey L (1997). Immunotherapy of recurrent genital herpes with re-
combinant herpes simplex virus type 2 glycoproteins D and B: results
of a placebo-controlled vaccine trial. J Infect Dis 176(5): 1129–1134.
137. Stanberry LR, Spruance SL, Cunningham AL, Bernstein DI, Mindel
A, Sacks S, Tyring S, Aoki FY, Slaoui M, Denis M, Vandepapeliere P, and
Dubin G (2002). Glycoprotein-D-adjuvant vaccine to prevent genital
herpes. N Engl J Med 347(21): 1652–1661.
138. Awasthi S, Mahairas GG, Shaw CE, Huang M-L, Koelle DM,
Posavad C, Corey L, and Friedman HM (2015). A Dual-Modality Herpes
Simplex Virus 2 Vaccine for Preventing Genital Herpes by Using Glyco-
protein C and D Subunit Antigens To Induce Potent Antibody Re-
sponses and Adenovirus Vectors Containing Capsid and Tegument
Proteins as T Cell Immunogens. J Virol 89(16): 8497–8509.
D. Jaishankar and D.Shukla (2016) Genital Herpes and STI
OPEN ACCESS
| www.microbialcell.com 450 Microbial Cell | SEPTEMBER 2016 | Vol. 3 No. 9
139. Awasthi S, Huang J, Shaw C, and Friedman HM (2014). Blocking
herpes simplex virus 2 glycoprotein E immune evasion as an approach
to enhance efficacy of a trivalent subunit antigen vaccine for genital
herpes. J Virol 88(15): 8421–8432.
140. Mo A, Musselli C, Chen H, Pappas J, Leclair K, Liu A, Chicz RM,
Truneh A, Monks S, Levey DL, and Srivastava PK (2011). A heat shock
protein based polyvalent vaccine targeting HSV-2: CD4(+) and CD8(+)
cellular immunity and protective efficacy. Vaccine 29(47): 8530–8541.
141. Wald A, Koelle DM, Fife K, Warren T, Leclair K, Chicz RM, Monks
S, Levey DL, Musselli C, and Srivastava PK (2011). Safety and immuno-
genicity of long HSV-2 peptides complexed with rhHsc70 in HSV-2
seropositive persons. Vaccine 29(47): 8520–8529.
