Daily Oral Emtricitabine/Tenofovir Preexposure Prophylaxis and Herpes Simplex Virus Type 2 among Men Who Have Sex with Men.
ABSTRACT In addition to protecting against HIV acquisition, antiretroviral preexposure prophylaxis (PrEP) using topical 1% tenofovir gel reduced Herpes simplex virus type 2 (HSV-2) acquisition by 51% among women in the CAPRISA 004 study. We examined the effect of daily oral emtricitabine/tenofovir (FTC/TDF) PrEP on HSV-2 seroincidence and ulcer occurrence among men who have sex with men (MSM) in the iPrEx trial.
HSV-2 serum testing was performed at screening and every six months. Among HSV-2-seronegative individuals, we used Cox regression models to estimate hazard ratios (HRs) of HSV-2 seroincidence associated with randomization to FTC/TDF. We used multiple imputation and Cox regression to estimate HRs for HSV-2 seroincidence accounting for drug exposure. We assessed ulcer occurrence among participants with prevalent or incident HSV-2 infection.
Of the 2,499 participants, 1383 (55.3%) tested HSV-2-seronegative at baseline, 892 (35.7%) tested positive, 223 (8.9%) had indeterminate tests, and one test was not done. Of the 1,347 HSV-2-seronegative participants with follow-up, 125 (9.3%) had incident HSV-2 infection (5.9 per 100 person-years). Compared with participants receiving placebo, there was no difference in HSV-2 seroincidence among participants receiving FTC/TDF (HR 1.1, 95% CI: 0.8-1.5; P = 0.64) or among participants receiving FTC/TDF with a concentration of tenofovir diphosphate >16 per million viable cells (HR 1.0, 95% CI: 0.3-3.5; P = 0.95). Among participants with HSV-2 infection, the proportion with ≥1 moderate or severe ulcer adverse event was twice as high in the placebo vs. active arm (5.9% vs. 2.9%, P = 0.02), but there were no differences in the proportions with ≥1 clinical examination during which perianal or groin ulcers were identified.
Tenofovir in daily oral FTC/TDF PrEP may reduce the occurrence of ulcers in individuals with HSV-2 infection but does not protect against HSV-2 incidence among MSM.
- SourceAvailable from: MJ Van de Laar[Show abstract] [Hide abstract]
ABSTRACT: To examine the prevalence and correlates of infection with herpes simplex virus type 2 (HSV-2) among sexually transmitted disease (STD) clinic attenders, we studied the prevalence of antibodies to HSV-2 and their association with risk behaviour. Data were collected in a cross-sectional study among STD clinic attenders in Amsterdam. Seropositivity for HSV-2 was determined in 1798 serum samples by means of a monoclonal antibody-blocking enzyme-linked immunoassay. The prevalence of HSV-2 antibodies was higher than expected: 32.3% in a population in which 3% had current genital herpes and 8% gave a history of genital herpes. Of those with HSV-2 antibodies, only 18% had a history of genital herpes. A strong independent association with the presence of HSV-2 antibodies was found for sexual behaviour, more specifically: homosexual orientation, increasing number of years of sexual activity, increasing number of lifetime partners, number of past gonococcal infections, having receptive anal and (or) vaginal contact. The presence of HSV-2 antibodies had a strong association with past sexual behaviour and, for both sexes, with receptive anal intercourse. HSV-2 antibodies may be used as a surrogate marker of sexual risk behaviour in comparing different populations over time.International Journal of Epidemiology 03/1998; 27(1):127-34. · 9.20 Impact Factor
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ABSTRACT: To determine the contribution of herpes simplex type 2 (HSV-2) infection to the risk of human immunodeficiency virus (HIV) acquisition, a systematic review of literature and data synthesis were done. Thirty-one studies addressed the risk of HIV infection in HSV-2-seropositive persons. For 9 cohort and nested case-control studies that documented HSV-2 infection before HIV acquisition, the risk estimate was 2.1 (95% confidence interval, 1.4-3.2). Thus, the attributable risk percentage of HIV to HSV-2 was 52%, and the population attributable risk percentage was 19% in populations with 22% HSV-2 prevalence but increased to 47% in populations with 80% HSV-2 prevalence. For 22 case-control and cross-sectional studies, the risk estimate was 3.9 (95% confidence interval, 3.1-5.1), but the temporal sequence of the 2 infections cannot be documented. Control strategies for HSV-2 need to be incorporated into control of sexually transmitted infections as a strategy for HIV prevention.The Journal of Infectious Diseases 02/2002; 185(1):45-52. · 5.78 Impact Factor
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ABSTRACT: The objective of this study was to define the positive predictive value (PPV) of the Focus herpes simplex virus type 2 (HSV-2) enzyme-linked immunosorbent assay (ELISA) in a low HSV-2 prevalence population and to develop a new test interpretation algorithm. HSV-2 Western blots were performed on sera from male sexually transmitted disease clinic patients testing HSV-2 ELISA-positive and used to define a new class of indeterminate HSV-2 ELISA result. HSV-2 Western blots were then prospectively performed on sequential sera with indeterminate HSV-2 ELISAs. Ninety-one (84%) of 108 HSV-2 ELISA-positive sera tested HSV-2 Western blot-positive. Western blot positivity was more common in men without herpes simplex virus type 1 (HSV-1) antibody than in those with HSV-1 antibody (93% vs 76%, P = 0.02) and in men with a history or clinical evidence of genital lesions (88% vs 80%, P = 0.30). Selectively raising the ELISA index value defining HSV-2 positivity from >1.1 to >or=3.0 either among HSV-1-positive men or among those without a history or clinical evidence of genital lesions increased the PPV to >or=93%. Prospective evaluation of an algorithm incorporating HSV-1 serostatus found that 11 of 70 persons with indeterminate HSV-2 ELISAs were Western blot-positive. Clinicians should consider selectively using a higher index value to define Focus ELISA HSV-2 positivity based on either HSV-1 serostatus or clinical circumstances.Sex Transm Dis 12/2005; 32(12):771-7. · 2.75 Impact Factor
Daily Oral Emtricitabine/Tenofovir Preexposure
Prophylaxis and Herpes Simplex Virus Type 2 among
Men Who Have Sex with Men
Julia L. Marcus1,2, David V. Glidden3, Vanessa McMahan1, Javier R. Lama4, Kenneth H. Mayer5,6,
Albert Y. Liu7, Orlando Montoya-Herrera8, Martin Casapia9, Brenda Hoagland10, Robert M. Grant1,3*
1Gladstone Institute of Virology and Immunology, San Francisco, California, United States or America, 2University of California, Berkeley, California, United States of
America, 3University of California San Francisco, San Francisco, California, United States of America, 4Asociacio ´n Civil Impacta Salud y Educacio ´n, Lima, Peru, 5Fenway
Institute, Fenway Health, Boston, Massachusetts, United States of America, 6Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States of America,
7Bridge HIV, San Francisco Department of Public Health, San Francisco, California, United States of America, 8Fundacio ´n Ecuatoriana Equidad, Guayaquil, Guayas,
Ecuador, 9Asociacio ´n Civil Selva Amazo ´nica, Iquitos, Peru, 10Instituto de Pesquisa Clı ´nica Evandro Chagas, Fundac ¸a ˜o Oswaldo Cruz, Rio de Janeiro, Brazil
Background: In addition to protecting against HIV acquisition, antiretroviral preexposure prophylaxis (PrEP) using topical
1% tenofovir gel reduced Herpes simplex virus type 2 (HSV-2) acquisition by 51% among women in the CAPRISA 004 study.
We examined the effect of daily oral emtricitabine/tenofovir (FTC/TDF) PrEP on HSV-2 seroincidence and ulcer occurrence
among men who have sex with men (MSM) in the iPrEx trial.
Methods: HSV-2 serum testing was performed at screening and every six months. Among HSV-2-seronegative individuals,
we used Cox regression models to estimate hazard ratios (HRs) of HSV-2 seroincidence associated with randomization to
FTC/TDF. We used multiple imputation and Cox regression to estimate HRs for HSV-2 seroincidence accounting for drug
exposure. We assessed ulcer occurrence among participants with prevalent or incident HSV-2 infection.
Results: Of the 2,499 participants, 1383 (55.3%) tested HSV-2-seronegative at baseline, 892 (35.7%) tested positive, 223
(8.9%) had indeterminate tests, and one test was not done. Of the 1,347 HSV-2-seronegative participants with follow-up, 125
(9.3%) had incident HSV-2 infection (5.9 per 100 person-years). Compared with participants receiving placebo, there was no
difference in HSV-2 seroincidence among participants receiving FTC/TDF (HR 1.1, 95% CI: 0.8–1.5; P=0.64) or among
participants receiving FTC/TDF with a concentration of tenofovir diphosphate .16 per million viable cells (HR 1.0, 95% CI:
0.3–3.5; P=0.95). Among participants with HSV-2 infection, the proportion with $1 moderate or severe ulcer adverse event
was twice as high in the placebo vs. active arm (5.9% vs. 2.9%, P=0.02), but there were no differences in the proportions
with $1 clinical examination during which perianal or groin ulcers were identified.
Conclusions: Tenofovir in daily oral FTC/TDF PrEP may reduce the occurrence of ulcers in individuals with HSV-2 infection
but does not protect against HSV-2 incidence among MSM.
Citation: Marcus JL, Glidden DV, McMahan V, Lama JR, Mayer KH, et al. (2014) Daily Oral Emtricitabine/Tenofovir Preexposure Prophylaxis and Herpes Simplex
Virus Type 2 among Men Who Have Sex with Men. PLoS ONE 9(3): e91513. doi:10.1371/journal.pone.0091513
Editor: D. William Cameron, University of Ottawa, Canada
Received October 25, 2013; Accepted February 8, 2014; Published March 17, 2014
Copyright: ? 2014 Marcus et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: This study was supported by the Division of Acquired Immunodeficiency Syndrome, National Institute of Allergy and Infectious Diseases, National
Institutes of Health, as a cooperative agreement (UO1 AI64002, to Dr. Grant), by the Bill and Melinda Gates Foundation, and by the Gladstone Institutes. The
funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: Co-author Javier Lama is a PLOS ONE Editorial Board member; this does not alter the authors’ adherence to all the PLOS ONE policies on
sharing data and materials. Dr. Mayer has received an unrestricted research grant from Gilead Sciences; this does not alter the authors’ adherence to all the PLOS
ONE policies on sharing data and materials. The remaining authors have declared that no competing interests exist.
* E-mail: firstname.lastname@example.org
Herpes simplex virus type 2 (HSV-2) is the primary cause of
genital ulcer disease worldwide. In 2003, an estimated 536 million
people aged 15–49 years were living with the infection, with
seroprevalence varying widely across settings and populations.
Most infected individuals are unaware of their infections. In
symptomatic infections, the virus causes painful ulcerative lesions
that can take two to four weeks to heal in primary outbreaks, and
recurrences can be frequent. The prevalence of HSV-2 infection
in the general population ranges from 10 to 60 percent, with
higher prevalences in female sex workers, men who have sex with
men (MSM), and certain regions of the world.  Among human
immunodeficiency virus (HIV)-infected populations, the estimated
seroprevalence of HSV-2 is 60–95 percent,  and individuals
coinfected with HIV have increased susceptibility to HSV-2
shedding and clinical manifestations of HSV-2 disease. 
Observational studies have found a two-to-three-fold higher risk
of HIV acquisition among individuals with HSV-2 infection, [5,6]
PLOS ONE | www.plosone.org1March 2014 | Volume 9 | Issue 3 | e91513
although randomized trials of HSV-2 treatment have not reduced
HIV acquisition or transmission [7,8].
In addition to protecting against HIV acquisition, antiretroviral
preexposure prophylaxis (PrEP) using tenofovir has been shown to
have a protective effect on HSV-2 in women. Pericoital 1%
vaginal tenofovir gel reduced the risk of HSV-2 acquisition by
51% in women participating in the CAPRISA 004 study.  In
fact, the protection against HSV-2 in that study was higher than
the effect of the gel on HIV acquisition, and a mathematical model
suggested that its effect on HSV-2 acquisition may have played a
role in its success in protecting against HIV.  Oral tenofovir-
based PrEP also reduced HSV-2 acquisition by 28% among
heterosexual men and women who were HIV-negative and HSV-
2-seronegative in the Partners PrEP study.  The anti-herpetic
effects of tenofovir have since been confirmed in vitro .
Protection against HSV-2 could enhance the public health
impact of tenofovir when used as an antiretroviral agent for HIV
prevention or treatment. Daily oral emtricitabine/tenofovir
(FTC/TDF) PrEP was shown to reduce HIV acquisition in
MSM in the iPrEx trial,  but it is unknown whether tenofovir
protects against HSV-2 acquisition or disease expression among
MSM. Using data from the randomized iPrEx study, our primary
aim was to determine the effect of daily oral FTC/TDF on HSV-2
seroincidence; secondarily, we examined the effect of FTC/TDF
on ulcer occurrence. To inform the development of HSV-2
prevention interventions among MSM, we also aimed to identify
demographic and behavioral risk factors for HSV-2 seroincidence
in the iPrEx cohort.
Materials and Methods
The iPrEx study (ClinicalTrials.gov: NCT00458393) was
approved by the Committee on Human Research at the
University of California, San Francisco, as well as local
institutional review boards (IRBs) at each study site: Comite ´
Institucional de Bioe ´tica, Asociacio ´n Civil Impacta Salud y
Educacio ´n, Lima, Peru; Universidad San Francisco de Quito,
IRB #1, Quito, Ecuador; Fenway Community Health Institu-
tional Review Board, Boston, MA; Comissa ˜o de E´tica para Ana ´lise
de Projetos de Pesquisa, CAPPesq Hospital das Clı ´nicas da
Faculdade de Medicina da USP, Sa ˜o Paulo, Brazil; Comite ˆ de
E´tica em Pesquisa, Hospital Universitario Clementino Fraga
Filho/Universidade Federal de Rio de Janeiro, Rio de Janeiro,
Brazil; Comite ˆ de E´tica em Pesquisa do Instituto de Pesquisa
Clı ´nica Evandro Chagas, Rio de Janeiro, Brazil; National IRB:
Comissa ˜o Nacional de E´tica em Pesquisa – CONEP, Ministe ´rio
da Sau ´de, Brası ´lia, Brazil; University of Cape Town Research
Ethics Committee, Cape Town, South Africa; Human Experi-
mentation Committee, Research Institute for Health Sciences,
Chiang Mai, Thailand; Ethical Review Committee for Research
in Human Subjects, Department of Medical Services, Ministry of
Public Health, Nonthaburi, Thailand; Research Ethics Commit-
tee, Faculty of Medicine, Chiang Mai University, Chiang Mai,
Thailand. Written informed consent was obtained from each
participant prior to enrollment in the study.
Study population and procedures
Details of the iPrEx trial have been previously published. 
Briefly, the study enrolled 2,499 MSM and transgender women at
risk for HIV infection at 11 sites in Peru, Ecuador, Brazil, South
Africa, Thailand, and the United States. Participants were
randomized to receive either daily oral FTC/TDF or placebo.
Monthly visits included medical history and symptom-directed
physical examination, adverse event (AE) assessment, study drug
dispensation, HIV testing, risk-reduction counseling, and adher-
ence assessment. Serologic testing for HSV-2 and physical
examinations for signs of sexually transmitted infections (STI)
were performed by clinicians at screening (baseline), every six
months during follow-up, and when the study drug was suspended,
or when prompted by symptoms reported during the monthly
medical examination. HIV infection status was determined using
two rapid antibody tests and confirmed by Western blot or RNA
testing. Sexual practices during the previous three months were
assessed by interviewer-administered questionnaires at screening
and quarterly visits during follow-up. The primary analysis of
iPrEx data included visits through the pre-specified cutoff date of
May 1, 2010, while the current analyses include follow-up visits
through September 30, 2010, the last visit at which participants
would have been expected to have had exposure to study drug.
HSV-2 infection status was determined using ELISA (Herpe-
Select, Focus Diagnostics). A negative HSV-2 test was defined as
having an index ratio (i.e., the ratio of the optical density of the
color generated by the sample to the optical density of a standard
calibrator; IR) ,0.9, while a positive HSV-2 test was defined as
having an IR $3.5.  Tests with an IR $0.9 and ,3.5 were
classified as indeterminate; participants with an IR ,3.5 were
retested at the next testing time point. The date of HSV-2
seroconversion was the date of the first positive HSV-2 test.
Perianal and groin ulcers were recorded if there was any ulcerative
lesion identified during STI examination, which may have
included ulcers associated with herpes, syphilis, chancroid,
lymphogranuloma venereum, or excoriation. Ulcer AEs were
identified by a clinician as an increase in ulcer severity or
frequency from baseline, including new onset of ulcers in
individuals without preexisting ulcer disease; severity was defined
according to the infection criteria in the National Institutes of
Health Division of AIDS Table for Grading the Severity of Adult
and Pediatric Adverse Events, December 2004. Only clinical AEs
that were Grade 2 or above were reported in iPrEx, per protocol;
thus, Grade 1 ulcers were not reported as ulcer AEs. Ulcer AEs
were identified during STI examination, or were self-reported by
participants and not confirmed on clinical examination if
symptoms resolved before the examination visit. Additionally,
ulcers that were self-reported but confirmed to be a different
clinical manifestation during examination were not classified as
ulcers or included in this analysis. In a subset of participants
assigned to the active arm, levels of FTC and tenofovir were
measured in plasma and peripheral blood mononuclear cells
(PBMCs). Participants with drug level tests were 1) in the DEXA
substudy, which evaluated the impact of FTC/TDF on bone and
body composition at seven sites in Peru, Brazil, South Africa,
Thailand, and the United States; and/or 2) matched active-arm
controls in the case-control substudy of HIV seroconverters (from
nine iPrEx sites with active-arm seroconversions). Approximately
one-third of the cohort had at least one drug level test.
For HSV-2 prevalence analyses, the dependent variable was
HSV-2 status at the screening visit, and independent variables
were randomization group and other baseline characteristics,
including age, level of education, transgender identity, number of
alcoholic drinks on days when drinking in the past month, and
sexual behaviors in the past three months. Sexual behavior
variables were number of anal sex partners, any receptive anal
intercourse with a condom (cRAI), any receptive anal intercourse
with no condom (ncRAI), any insertive anal intercourse with a
condom (cIAI), and any insertive anal intercourse with no condom
Daily Oral FTC/TDF PrEP and HSV-2 among MSM
PLOS ONE | www.plosone.org2March 2014 | Volume 9 | Issue 3 | e91513
(ncIAI). We used chi-square tests and log-binomial models to
identify factors associated with HSV-2 prevalence at baseline. We
also examined the association of age with HSV-2 prevalence and
HSV-2 seroincidence using chi-square tests for trend.
For HSV-2 seroincidence analyses, the dependent variable was
time to HSV-2 seroconversion during follow-up, and independent
variables were randomization group and the demographic and
behavioral variables examined in HSV-2 prevalence analyses. We
calculated crude rates of HSV-2 seroincidence by randomization
group and baseline demographic and behavioral characteristics,
including only participants who tested seronegative for HSV-2 at
the screening visit. Person-time at risk included time from study
enrollment to the first of HSV-2 infection, study drug discontin-
uation, or loss to follow-up. We estimated the time-to-event
distribution by randomization group using Kaplan-Meier meth-
odology. We used Cox regression models to estimate unadjusted
and adjusted hazard ratios (HRs) for time to HSV-2 seroincidence.
An intent-to-treat analysis included only randomization group; to
identify factors associated with time to HSV-2 seroincidence, a
multivariable model additionally included demographic and
behavioral variables that were statistically significant at the
P,0.05 level in unadjusted analyses. Sexual behavior variables
were time-updated in models at approximately three-month
intervals, while other covariates were treated as fixed. All models
were stratified by study site.
Among the same participants, we also conducted an as-treated
analysis that accounted for study drug use among participants
receiving FTC/TDF. Because drug level testing was only
conducted in a subset of participants and visits, drug levels were
imputed for participants in both arms at any monthly visit missing
drug level data using chained equations and predictive means
matching. Predictors in the imputations included study week,
study site, baseline number of sexual partners, baseline ncRAI,
transgender identity, body mass index, weight, report of an STI in
the six months before screening, secondary education, circumci-
sion, baseline HSV-2 infection, age, and number of drinks on days
when the participant drank in the prior month. Covariates were
used to predict the probability of having detectable drug and the
probability that the level of tenofovir diphosphate (TFV-DP) in
PBMCs was .16 fmol per million viable cells, the concentration
associated with an estimated 90% reduction in HIV acquisition.
 Drug levels were multiply imputed  for visits at which
drug level testing was not conducted but the participant was still
taking study drug, with 200 imputations per observation.  We
then used site-stratified Cox regression to estimate HRs for HSV-2
seroincidence associated with being randomized to the FTC/TDF
arm and having detectable drug with TFV-DP #16 or being
randomized to the FTC/TDF arm and having detectable drug
with TFV-DP .16. Unadjusted models included only a time-
dependent covariate for drug detection, while adjusted models also
included age, level of education, transgender identity, number of
alcoholic drinks on days when drinking in the past month, and
sexual behaviors in the past three months (number of anal sex
partners, cRAI, ncRAI, cIAI, and ncIAI). Sexual behavior
variables were time-updated at approximately three-month
To examine the effect of FTC/TDF on HSV-2 disease
expression, we analyzed the occurrence of ulcers among those
who tested seropositive for HSV-2 at baseline or during follow-up.
To eliminate the potential effect of HIV infection on ulcer
occurrence, participants were excluded if the HSV-2 diagnosis
occurred at or after HIV seroconversion, and ulcers were excluded
if they occurred at or after HIV seroconversion. We estimated the
proportion of participants with $1 ulcer AE classified as Grade 2
or above (i.e., moderate, severe, or potentially life-threatening),
$1 STI examination during which a perianal ulcer was detected,
and $1 STI examination during which a groin ulcer was detected,
using chi-square tests to compare proportions by randomization
group. We assessed the proportion of visits at which symptoms
were reported that prompted an STI examination, using a chi-
square test for comparison by randomization group. We also
examined ulcers occurring after HIV seroconversion to determine
whether there were differences in ulcer occurrence by random-
ization group in the absence of study drug.
All analyses were conducted in SAS 9.3 or Stata 12.
Characteristics of the 2,499 iPrEx participants have been
described previously.  Briefly, all participants were born male
and 313 (13.0%) identified as transgender or as women. The mean
age at enrollment was 25 years (range 18–67), and the majority of
participants were enrolled at the three study sites in Peru (1,400,
56.0%). At baseline, over half of participants (59.4%) reported
having had ncRAI in the past three months. Among participants
with prevalent or incident HSV-2 infection, 11.6% used acyclovir
or valacyclovir during study follow-up.
Of the 2,499 participants, 1383 (55.3%) tested negative for
HSV-2 at baseline, 892 (35.7%) tested positive, 223 (8.9%) had
indeterminate tests, and one test was not done. Of the 223 with
indeterminate tests at baseline, 114 (51.1%) tested positive for
HSV-2 infection at some point during follow-up. Factors
associated with testing seropositive for HSV-2 at baseline included
older age (P trend ,0.001; Figure 1a), transgender identity
(prevalence ratio [PR] 2.0, 95% confidence interval [CI]: 1.8–2.2;
P,0.001), and not having a secondary education (PR 1.4, 95%
CI: 1.2–1.5; P,0.001). The prevalence of HSV-2 infection was
highest among participants living in Peru (46.0%), Brazil (37.8%),
and Ecuador (37.3%), with lower prevalence among participants
living in Thailand (6.4%), South Africa (17.6%), and the United
States (27.1%; P,0.001). Randomization group was not associ-
ated with HSV-2 prevalence at baseline (P=0.44). In multivar-
iable analysis, all factors remained significantly associated with
HSV-2 prevalence with the exception of level of education.
FTC/TDF and time to HSV-2 seroincidence
Characteristics of 1,383 participants who tested seronegative for
HSV-2 at baseline are presented by randomization group in
Table 1. There were no differences in baseline characteristics by
randomization group, with the exception of cRAI in the past three
months being reported more frequently in the placebo arm
Of the 1,383 participants who tested seronegative for HSV-2 at
baseline, 36 (2.6%) did not contribute person-time to incidence
analyses because they were retrospectively found to be HIV-
infected at baseline, tested seropositive for HSV-2 at the
enrollment visit subsequent to screening, or were lost to follow-
up after enrollment. Of the remaining 1,347 seronegative
participants, 125 (9.3%) were diagnosed with HSV-2 during
follow-up, representing an incidence of 5.9 per 100 person-years
(Table 2). In unadjusted analysis, HSV-2 incidence decreased with
age, with the highest rate among participants aged ,25 years (7.1
per 100 person-years) and the lowest rate among participants aged
$40 years (1.6 per 100 person-years; P trend =0.001). Country of
residence was also associated with HSV-2 incidence, with the
Daily Oral FTC/TDF PrEP and HSV-2 among MSM
PLOS ONE | www.plosone.org3 March 2014 | Volume 9 | Issue 3 | e91513
highest rate among participants living in Ecuador (9.7 per 100
person-years) and the lowest rate among participants living in
Thailand (1.7 per 100 person-years). The only behavioral factor
associated with time to HSV-2 incidence was ncRAI in the past
three months (HR 2.0, 95% CI: 1.4-3.0; P,0.001). In multivar-
iable analysis, younger age and ncRAI remained associated with
time to HSV-2 incidence, while level of education, transgender
identity, alcohol use, and other sexual behaviors were not
associated with time to HSV-2 seroincidence.
Of those who acquired HSV-2 during follow-up, 65 were in the
FTC/TDF group (incidence of 6.1 per 100 person-years) and 60
were in the placebo group (incidence of 5.6 per 100 person-years).
There was no significant difference in time to HSV-2 incidence
among participants assigned to the FTC/TDF arm compared
with those assigned to the placebo arm (HR 1.1, 95% CI: 0.8–1.5;
P=0.64; Figure 2). Compared with participants in the placebo
arm, there was also no difference in time to HSV-2 incidence
among participants in the FTC/TDF group with a detectable
drug level and #16 TFV-DP (HR 1.0, 95% CI: 0.4–2.5; P=0.97),
with similar results among those in the FTC/TDF group with
.16 TFV-DP (HR 1.0, 95% CI: 0.3–3.5; P=0.95). Results did
not change after adjustment for age, education, transgender
identity, alcohol use, or sexual behaviors.
FTC/TDF and ulcer occurrence
A total of 1,019 participants tested seropositive for HSV-2 at
baseline or during follow-up; of those, 22 (2.2%) tested seropositive
for HSV-2 after HIV seroconversion. Among the remaining 997,
there were 72 ulcer AEs classified as Grade 2 or above, with 43
participants (4.3%) having $1 ulcer AE. Among the 72 ulcer AEs,
23 (31.9%) were confirmed on STI examination; for the
remainder, symptoms resolved before an examination was
conducted. Compared with participants in the placebo arm, the
proportion of participants with $1 ulcer AE was reduced by half
among participants in the FTC/TDF arm (2.9% vs. 5.9%,
P=0.02; Figure 3). There were no differences by randomization
group in the proportion of participants with $1 STI examination
during which a perianal ulcer (FTC/TDF 3.5% vs. placebo 4.7%,
P=0.37) or groin ulcer (FTC/TDF 2.5% vs. placebo 1.9%,
P=0.51) was identified; results were similar after excluding
participants with a positive syphilis rapid plasma reagin test at
the same visit. However, symptoms that prompted STI examina-
tion were less common in the FTC/TDF arm compared with the
placebo arm (3.7% vs. 7.4%, P=0.01).
Among the 89 participants with prevalent or incident HSV-2
infection who also seroconverted to HIV during study follow-up,
6.7% had $1 ulcer AE, 6.7% had $1 STI examination during
which a perianal ulcer was identified, and 5.6% had $1 STI
examination during which a groin ulcer was identified after HIV
seroconversion, and thus after stopping study drug. The propor-
tions with each type of ulcer did not differ between participants in
the FTC/TDF arm and participants in the placebo arm.
Finally, the iPrEx protocol did not use the HSV-2 test
manufacturer’s suggested cutoffs for indeterminate (IR $0.9 and
#1.1) or positive (IR.1.1) tests, but conducting the incidence and
ulcer analyses using the cutoffs from the package insert yielded
In this analysis of participants in the iPrEx trial of daily oral
FTC/TDF PrEP, we found no association between FTC/TDF
and incidence of HSV-2 infection, even after accounting for actual
use of FTC/TDF using drug level test results in a subset. The
proportion of participants in the FTC/TDF arm with at least one
ulcer AE classified as Grade 2 or above was half of that seen in the
placebo arm, and this association was no longer present among
participants who had stopped study drug after HIV seroconver-
sion; however, this finding was not confirmed by ulcers identified
during STI examinations and may have included ulcers of non-
herpetic etiologies. In contrast to the 51% reduction in HSV-2
incidence among women randomized to use a 1% tenofovir
topical gel in CAPRISA 004,  our results suggest that tenofovir
in daily oral FTC/TDF may reduce the occurrence of ulcers in
individuals with HSV-2 infection but does not protect against
HSV-2 incidence among MSM.
The difference between the effects on HSV-2 incidence seen in
CAPRISA and iPrEx may be due to differences in the route of
transmission, method of drug delivery, or level of drug exposure.
We found that the primary risk factor for incident HSV-2 infection
in iPrEx was receptive anal intercourse without a condom, a
finding that has been reported in several studies of behavioral risk
factors for HSV-2 acquisition in MSM. [18,19,20] The rectal
mucosa and cervicovaginal mucosa may differ in their suscepti-
bility to HSV-2 infection. Additionally, although oral dosing of
tenofovir achieves drug concentrations that are 20–100 times
higher in rectal tissue than in vaginal and cervical tissue, [21,22]
topical application of tenofovir achieves a more than 100-fold
higher concentration of the drug in the genital tract than oral
dosing; [23,24] furthermore, the inhibitory concentration for
tenofovir is substantially higher for HSV-2 relative to HIV. 
Drug concentration is also affected by adherence; while iPrEx
Figure 1. Baseline prevalence of HSV-2 and incidence of HSV-2
during study follow-up by age at enrollment. Figure 1a shows
HSV-2 prevalence at baseline by age group at enrollment, while
Figure 1b shows HSV-2 incidence during follow-up by age group at
enrollment. HSV-2, herpes simplex virus type 2.
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PLOS ONE | www.plosone.org4 March 2014 | Volume 9 | Issue 3 | e91513
participants reported taking over 90% of study drug doses, drug
was detectable in the blood specimens of only 50% of participants
tested in a random subsample. Although we did not observe
an effect of FTC/TDF even after accounting for drug levels, it
may be that oral FTC/TDF will be shown to have an impact on
HSV-2 incidence in settings where drug exposure is higher as a
result of more consistent pill taking, such as the Partners PrEP
We found that FTC/TDF was associated with a reduction in
moderate or severe ulcer AEs among participants with HSV-2
infection, although this was not confirmed by clinical examination
findings. Given the inhibition of HSV-2 replication observed after
administration of tenofovir, it is biologically plausible that FTC/
TDF reduced the frequency or severity of ulcers. Unlike acyclovir,
tenofovir does not require the presence of the herpes virus for drug
activation, suggesting that it may suppress ulcers before phos-
phorylation occurs. However, topical dosing may be required to
achieve a concentration of drug in tissue sufficient to inhibit HSV-
2 shedding,  and a study of adults coinfected with HIV and
HSV-2 found no impact of oral tenofovir on rates of HSV-2
shedding.  More information is needed about the impact of
oral and topical tenofovir on the clinical expression of HSV-2
There are several limitations of our analysis. First, although our
intent-to-treat incidence analysis by treatment arm was strength-
ened by randomization, our findings may have been diluted by low
levels of adherence among participants. While drug levels were not
available for all participants or visits, we were able to conduct an
incidence analysis that accounted for drug exposure but was
subject to the limitations of multiple imputation of a substantial
amount of missing data, potential unmeasured confounding, and
wide confidence intervals. Of participants with prevalent or
incident HSV-2, a small proportion were prescribed acyclovir or
valacyclovir during study follow-up; if use of these medications
biased our analysis toward the null, it is possible that the effect of
FTC/TDF on ulcers is stronger than what we observed in our
study. Our behavioral risk factor analysis included number of anal
sex partners, position during anal sex, and condom use in the last
Table 1. Characteristics of participants testing HSV-2 seronegative at baseline by randomization group.a
FTC/TDF (n=692) Placebo (n=691)P-value
,25 413 (60)449 (65)
25–29 139 (21)123 (18)
30–3461 (9)52 (8)
35–39 28 (4)34 (5)
$4051 (7) 33 (5)
Completed secondary education0.38
Yes557 (82)571 (84)
No126 (18) 114 (17)
Yes 40 (6)46 (7)
No 652 (94)645 (93)
No. alcoholic drinks on drinking days, past month0.11
0–4 323 (48)294 (43)
$5 354 (52)383 (57)
Number of anal sex partners, past 3 months0.87
0–1 90 (13)85 (12)
2–5 291 (42)287 (42)
$6 311 (45) 319 (46)
Insertive anal intercourse with condom, past 3 months0.94
Yes 343 (50)350 (51)
No 349 (50) 341 (49)
Insertive anal intercourse with no condom, past 3 months0.57
Yes 419 (61)408 (59)
No 273 (39)283 (41)
Receptive anal intercourse with condom, past 3 months0.01
Yes 292 (42)340 (49)
No 400 (58) 351 (51)
Receptive anal intercourse with no condom, past 3 months0.11
Yes329 (48)358 (52)
No 363 (52)333 (48)
aHSV-2, herpes simplex virus type 2. Ns may not add up to column totals due to missing data.
Daily Oral FTC/TDF PrEP and HSV-2 among MSM
PLOS ONE | www.plosone.org5 March 2014 | Volume 9 | Issue 3 | e91513
three months, but we did not include oral sex as a potential risk
factor for HSV-2 seroincidence; however, because HSV-2 is
infrequently transmitted through oral sex, we expect this had a
negligible effect on our analysis. There may have been some
misclassification of HSV-2 results, particularly among participants
with HSV-1 antibody,  but there is no expectation that this
would differ by randomization arm. Some ulcer AEs were
identified by self-report, which may be subject to inaccuracy or
low sensitivity for HSV-2 recurrences, and we were not able to use
HSV PCR to confirm that ulcers were herpetic. Finally, AEs only
captured ulcers that increased in severity or frequency; thus, the
reduction in ulcers associated with FTC/TDF may have been
greater than what we observed.
Table 2. Baseline characteristics by time to HSV-2 seroincidence.a
n (%) Events/PY
Adjusted HR (95%
1347 (100) 125/21345.9
Age group 0.02
,25809 (60) 94/13227.111
25–29271 (20) 21/412 5.10.7 (0.4, 1.1) 0.7 (0.4, 1.1)
30–34121 (9) 5/188 2.70.3 (0.1, 0.8) 0.3 (0.1, 0.8)
35–3963 (5)3/87 3.5 0.4 (0.1, 1.3)0.4 (0.1, 1.5)
$40 83 (6) 2/1251.6 0.2 (0.0, 0.7) 0.2 (0.0, 0.8)
Completed secondary education
Yes 1103 (83) 107/1741 6.11.3 (0.8, 2.2)
No230 (17) 18/362 5.01
Yes 85 (6)10/126 8.01.5 (0.8, 2.9)
FTC/TDF671 (50) 65/10626.1 1.1 (0.8, 1.5)1.2 (0.8, 1.7)0.41
Placebo676 (50) 60/1071 5.611
No. alcoholic drinks on drinking days, past month
0–4 608 (46)56/926 6.01
$5711 (54) 65/11555.60.9 (0.6, 1.3)
Number of anal sex partners, past 3 monthsc
0–1 169 (13) 18/2317.81
2–5563 (42) 42/846 5.00.6 (0.4, 1.1)
$6 615 (46)65/10566.2 0.7 (0.4, 1.4)
Insertive anal intercourse with condom, past 3
Yes681 (51)52/10604.90.9 (0.9, 1.0)
No666 (49) 73/1074 6.81
Insertive anal intercourse with no condom, past 3
Yes802 (60)77/13045.91.0 (0.7, 1.4)
No 545 (40) 48/8295.81
Receptive anal intercourse with condom, past 3
Yes617 (46)67/9617.01.0 (1.0, 1.0)
Receptive anal intercourse with no condom, past
Yes671 (50)86/10917.92.0 (1.4, 3.0) 2.0 (1.3, 2.9)
aHSV-2, herpes simplex virus type 2; PY, person-years; HR, hazard ratio. Among participants testing HSV-2 seronegative at baseline. Ns may not add up to column totals
due to missing data.
bUnadjusted HRs were derived from univariable models, while adjusted HRs were derived from multivariable models including variables that were statistically significant
at the P,0.05 level in unadjusted analyses. Models were stratified by study site.
cSexual behavior variables are shown at baseline for incidence estimates and were time-updated in models.
Daily Oral FTC/TDF PrEP and HSV-2 among MSM
PLOS ONE | www.plosone.org6March 2014 | Volume 9 | Issue 3 | e91513
To our knowledge, this is the first analysis of the effect of daily
oral FTC/TDF PrEP on HSV-2 incidence and ulcer occurrence
among MSM. In our study, oral FTC/TDF did not reduce the
acquisition of HSV-2 infection. Although we found that FTC/
TDF was associated with a reduction in ulcer AE occurrence, this
finding was not confirmed by ulcers identified on clinical
examination and should be replicated in settings where ulcer
etiology can be confirmed.
We thank the participants for their dedication to HIV prevention and the
study, as well as the site investigators and their staff for following the cohort
and collecting the data. We also thank Maya Petersen, M.D., Ph.D. from
the Division of Epidemiology, School of Public Health, University of
California, Berkeley, for her helpful comments on the manuscript.
Conceived and designed the experiments: DVG VM JRL KHM AYL
OMH MC BH RMG. Performed the experiments: VM JRL KHM AYL
OMH MC BH RMG. Analyzed the data: JLM DVG. Wrote the paper:
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