[Show abstract][Hide abstract] ABSTRACT: Background Defining mucosal immune responses and inflammation to candidate human immunodeficiency virus type 1 (HIV-1) vaccines represents
a current research priority for the HIV-1 vaccine field. In particular, it is unclear whether intramuscular immunization can
elicit immune responses at mucosal surfaces in humans.
The Journal of Infectious Diseases 08/2014; 211(4). DOI:10.1093/infdis/jiu485 · 5.78 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The viral reservoir represents a critical challenge for human immunodeficiency virus type 1 (HIV-1) eradication strategies. However, it remains unclear when and where the viral reservoir is seeded during acute infection and the extent to which it is susceptible to early antiretroviral therapy (ART). Here we show that the viral reservoir is seeded rapidly after mucosal simian immunodeficiency virus (SIV) infection of rhesus monkeys and before systemic viraemia. We initiated suppressive ART in groups of monkeys on days 3, 7, 10 and 14 after intrarectal SIVMAC251 infection. Treatment with ART on day 3 blocked the emergence of viral RNA and proviral DNA in peripheral blood and also substantially reduced levels of proviral DNA in lymph nodes and gastrointestinal mucosa as compared with treatment at later time points. In addition, treatment on day 3 abrogated the induction of SIV-specific humoral and cellular immune responses. Nevertheless, after discontinuation of ART following 24 weeks of fully suppressive therapy, virus rebounded in all animals, although the monkeys that were treated on day 3 exhibited a delayed viral rebound as compared with those treated on days 7, 10 and 14. The time to viral rebound correlated with total viraemia during acute infection and with proviral DNA at the time of ART discontinuation. These data demonstrate that the viral reservoir is seeded rapidly after intrarectal SIV infection of rhesus monkeys, during the 'eclipse' phase, and before detectable viraemia. This strikingly early seeding of the refractory viral reservoir raises important new challenges for HIV-1 eradication strategies.
[Show abstract][Hide abstract] ABSTRACT: Foreskin is the principal site of heterosexual HIV-1 infection in men. However, little is known about HIV-1-specific immune responses or inflammation in foreskin. To the best of our knowledge, no previous studies have assessed immune responses to candidate HIV-1 vaccines in foreskin. Using the rhesus monkey model, we show that intramuscular immunization with adenovirus serotype 26 and 35 vectors expressing SIV antigens elicited durable SIV Gag-specific CD4+ and CD8+ T cell responses in foreskin that were detectable for more than 1 year following vaccination. Gag-specific CD4+ and CD8+ T cells were also detectable in foreskin of SIV- and SHIV-infected animals and were at least comparable in magnitude to those in peripheral blood. However, unlike peripheral blood T cells, the majority of foreskin T cells exhibited transitional memory or effector memory phenotype and expressed higher levels of the activation markers CD69, HLA-DR and CCR5, although vaccination did not further enhance foreskin CD4+ T cell activation. These findings suggest that systemic vaccination strategies can elicit potentially important SIV-specific cellular immunity in foreskin. Further characterization of vaccine-elicited immune responses and inflammation in foreskin is warranted.Importance This manuscript demonstrates the induction of SIV-specific cellular immune responses in foreskin by adenovirus serotype 26 and 35 vaccine vectors. Foreskin T cells were more activated than peripheral blood T cells, but foreskin T cells were not further activated by vaccination. These findings suggest that alternative serotype adenovirus vectors induce potentially important immune responses in foreskin.
Journal of Virology 01/2014; DOI:10.1128/JVI.03771-13 · 4.65 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Transcutaneous drug delivery from planar skin patches is effective for small-molecule drugs and skin-permeable vaccine adjuvants. However, to achieve efficient delivery of vaccines and other macromolecular therapeutics into the skin, penetration of the stratum corneum is needed. Topically applied skin patches with micron-scale projections ('microneedles') pierce the upper layers of the skin and enable vaccines that are coated on or encapsulated within the microneedles to be dispersed into the skin. Although millimeter-scale syringes have shown promise for vaccine delivery in humans and technologies, such as the Dermaroller (Dermaroller, Wolfenbüttel, Germany), exist for creating microscale punctures in the skin for delivery of solutions of therapeutics, solid microprojection microneedles coated with dry vaccine formulations offer a number of valuable features for vaccination, including reduced risk of blood-borne pathogen transmission or needle-stick injury, the potential for vaccine administration by minimally trained personnel or even self administration and the use of solid-state vaccine formulations that may reduce or eliminate cold-chain requirements in vaccine distribution. Recent studies in mice have demonstrated the ability of microneedles to effectively deliver vaccines to the skin, eliciting protective immunity to influenza, hepatitis C and West Nile virus.
[Show abstract][Hide abstract] ABSTRACT: Human immunodeficiency virus type 1 (HIV-1)-specific monoclonal antibodies with extraordinary potency and breadth have recently been described. In humanized mice, combinations of monoclonal antibodies have been shown to suppress viraemia, but the therapeutic potential of these monoclonal antibodies has not yet been evaluated in primates with an intact immune system. Here we show that administration of a cocktail of HIV-1-specific monoclonal antibodies, as well as the single glycan-dependent monoclonal antibody PGT121, resulted in a rapid and precipitous decline of plasma viraemia to undetectable levels in rhesus monkeys chronically infected with the pathogenic simian-human immunodeficiency virus SHIV-SF162P3. A single monoclonal antibody infusion afforded up to a 3.1 log decline of plasma viral RNA in 7 days and also reduced proviral DNA in peripheral blood, gastrointestinal mucosa and lymph nodes without the development of viral resistance. Moreover, after monoclonal antibody administration, host Gag-specific T-lymphocyte responses showed improved functionality. Virus rebounded in most animals after a median of 56 days when serum monoclonal antibody titres had declined to undetectable levels, although, notably, a subset of animals maintained long-term virological control in the absence of further monoclonal antibody infusions. These data demonstrate a profound therapeutic effect of potent neutralizing HIV-1-specific monoclonal antibodies in SHIV-infected rhesus monkeys as well as an impact on host immune responses. Our findings strongly encourage the investigation of monoclonal antibody therapy for HIV-1 in humans.
[Show abstract][Hide abstract] ABSTRACT: The global diversity of HIV-1 represents a critical challenge facing HIV-1 vaccine development. HIV-1 mosaic antigens are bioinformatically optimized immunogens designed for improved coverage of HIV-1 diversity. However, the protective efficacy of such global HIV-1 vaccine antigens has not previously been evaluated. Here, we demonstrate the capacity of bivalent HIV-1 mosaic antigens to protect rhesus monkeys against acquisition of infection following heterologous challenges with the difficult-to-neutralize simian-human immunodeficiency virus SHIV-SF162P3. Adenovirus/poxvirus and adenovirus/adenovirus vector-based vaccines expressing HIV-1 mosaic Env, Gag, and Pol afforded a significant reduction in the per-exposure acquisition risk following repetitive, intrarectal SHIV-SF162P3 challenges. Protection against acquisition of infection correlated with vaccine-elicited binding, neutralizing, and functional nonneutralizing antibodies, suggesting that the coordinated activity of multiple antibody functions may contribute to protection against difficult-to-neutralize viruses. These data demonstrate the protective efficacy of HIV-1 mosaic antigens and suggest a potential strategy for the development of a global HIV-1 vaccine. PAPERCLIP:
[Show abstract][Hide abstract] ABSTRACT: Background. Adenovirus serotype 26 (Ad26) has been developed as a novel candidate vaccine vector for HIV-1 and other pathogens. The primary safety and immunogenicity data from IPCAVD 001, the first-in-human evaluation of a prototype Ad26 vector-based vaccine expressing clade A HIV-1 Env (Ad26.ENVA.01), is reported concurrently with this manuscript. Here we characterize in greater detail the humoral and cellular immune responses elicited by Ad26.ENVA.01 in humans.Methods. Samples from IPCAVD 001 were utilized for humoral and cellular immunogenicity assays.Results. We observed a dose-dependent expansion of the magnitude, breadth, and epitopic diversity of Env-specific binding antibody responses elicited by this vaccine. Antibody-dependent cell-mediated phagocytosis, virus inhibition, and degranulation functional activity was also observed. Env-specific cellular immune responses induced by the vaccine included multiple CD8+ and CD4+ T lymphocyte memory subpopulations and cytokine secretion phenotypes, although cellular immune breadth was limited. Baseline vector-specific T lymphocyte responses were common but did not impair Env-specific immune responses in this study.Conclusion. Ad26.ENVA.01 elicited a broad diversity of humoral and cellular immune responses in humans. These data support the further clinical development of Ad26 as a candidate vaccine vector.
The Journal of Infectious Diseases 11/2012; 207(2). DOI:10.1093/infdis/jis671 · 5.78 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A pediatric human immunodeficiency virus type 1 (HIV-1) vaccine would be desirable to protect infants against HIV-1 transmission from breast-feeding. Such a vaccine would need to induce protective immunity at mucosal surfaces in neonates as soon as possible after birth. Recombinant adenovirus (rAd) vectors have been shown to elicit potent systemic and mucosal virus-specific immune responses in adult nonhuman primates and humans, but these vectors have not previously been comprehensively studied in infants. In this study, we demonstrate that a single injection of rAd26 encoding simian immunodeficiency virus mac239 (SIVmac239) Gag on the day of birth elicited detectable Gag-specific cellular immune responses in rhesus monkeys, but these responses were transient and waned quickly. In contrast, an accelerated heterologous prime-boost regimen involving administration of rAd35 at birth and rAd26 at 4 weeks of life elicited potent and durable Gag-specific cellular and humoral immune responses in neonatal rhesus monkeys, including mucosal responses that remained detectable at 1 year of age. These results suggest the potential of an accelerated heterologous rAd prime-boost regimen as a candidate HIV-1 vaccine for newborns.
Journal of Virology 05/2012; 86(15):7829-35. DOI:10.1128/JVI.00512-12 · 4.65 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Preclinical studies of human immunodeficiency virus type 1 (HIV-1) vaccine candidates have typically shown post-infection virological control, but protection against acquisition of infection has previously only been reported against neutralization-sensitive virus challenges. Here we demonstrate vaccine protection against acquisition of fully heterologous, neutralization-resistant simian immunodeficiency virus (SIV) challenges in rhesus monkeys. Adenovirus/poxvirus and adenovirus/adenovirus-vector-based vaccines expressing SIV(SME543) Gag, Pol and Env antigens resulted in an 80% or greater reduction in the per-exposure probability of infection against repetitive, intrarectal SIV(MAC251) challenges in rhesus monkeys. Protection against acquisition of infection showed distinct immunological correlates compared with post-infection virological control and required the inclusion of Env in the vaccine regimen. These data demonstrate the proof-of-concept that optimized HIV-1 vaccine candidates can block acquisition of stringent, heterologous, neutralization-resistant virus challenges in rhesus monkeys.
[Show abstract][Hide abstract] ABSTRACT: The induction of potent and durable cellular immune responses in both peripheral and mucosal tissues may be important for the development of effective vaccines against human immunodeficiency virus type 1 and other pathogens. In particular, effector responses at mucosal surfaces may be critical to respond rapidly to incoming mucosal pathogens. Here we report that intramuscular injection of nonreplicating recombinant adenovirus (rAd) vectors into rhesus monkeys induced remarkably durable simian immunodeficiency virus (SIV)-specific T lymphocyte responses that persisted for over 2 years in both peripheral blood and multiple mucosal tissues, including colorectal, duodenal, and vaginal biopsy specimens, as well as bronchoalveolar lavage fluid. In peripheral blood, SIV-specific T lymphocytes underwent the expected phenotypic evolution from effector memory T cells (T(EM)) to central memory T cells (TCM) following vaccination. In contrast, mucosal SIV-specific T lymphocytes exhibited a persistent and durable T(EM) phenotype that did not evolve over time. These data demonstrate that nonreplicating rAd vectors induce durable and widely distributed effector memory mucosal T lymphocyte responses that are phenotypically distinct from peripheral T lymphocyte responses. Vaccine-elicited T(EM) responses at mucosal surfaces may prove critical for affording protection against invading pathogens at the mucosal portals of entry.
Journal of Virology 09/2011; 85(21):11007-15. DOI:10.1128/JVI.05346-11 · 4.65 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Post hoc analysis of the phase 2b Step study evaluating a recombinant adenovirus serotype 5 (rAd5)-based HIV-1 vaccine candidate suggested a potential increased risk of HIV-1 acquisition in subjects who were baseline Ad5 seropositive and uncircumcised. These concerns had a profound impact on the HIV-1 vaccine development field, although the mechanism underlying this observation remains unknown. It has been hypothesized that rAd5 vaccination of baseline Ad5-seropositive individuals may have resulted in anamnestic, vector-specific CD4(+) T lymphocytes that could have trafficked to mucosal sites and served as increased targets for HIV-1 infection. Here we show that Ad5-specific CD4(+) T lymphocyte responses at mucosal sites following rAd5-Gag/Pol/Nef vaccination were comparable in rhesus monkeys with and without baseline Ad5 immunity. Moreover, the total cellular inflammatory infiltrates and the CD3(+), CD4(+), HLA-DR(+), Ki67(+), and langerin(+) cellular subpopulations in colorectal and foreskin mucosa were similar in both groups. Thus, no greater trafficking of Ad5-specific CD4(+) T lymphocytes to mucosal target sites was observed following rAd5 vaccination of rhesus monkeys with baseline Ad5 immunity. These findings from this nonhuman primate model provide evidence against the hypothesis that recruitment of vector-specific target cells to mucosal sites led to increased HIV-1 acquisition in Ad5-seropositive, uncircumcised vaccinees in the Step study.
Journal of Virology 10/2010; 84(19):9810-6. DOI:10.1128/JVI.01157-10 · 4.65 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Plasmid DNA immunizations induce low levels but a broad spectrum of cellular and humoral immune responses. Here, we investigate the potential of co-stimulation through 4-1BB as an adjuvant for a HIV-1 DNA vaccine in mice. We designed plasmid DNAs expressing either the membrane bound or soluble form of 4-1BBL, and compared with the agonistic anti-4-1BB Ab for their ability to adjuvant the Gag DNA vaccine. Both, anti-4-1BB agonistic Ab as well as 4-1BBL DNA enhanced the Gag-specific cellular immune responses. However, in complete contrast to the agonistic Ab that suppressed humoral immunity to Gag, 4-1BBL DNA adjuvanted vaccines enhanced Gag-specific IgG responses. Importantly, the expression of Gag and 4-1BBL from the same plasmid was critical for the adjuvant activity. Collectively, our data suggest that for a HIV-1 vaccine where both antigen-specific cellular and humoral immunity are desirable, 4-1BBL expressed by a DNA vaccine is a superior adjuvant than anti-4-1BB agonistic Ab.
[Show abstract][Hide abstract] ABSTRACT: The immunologic basis for the potential enhanced HIV-1 acquisition in adenovirus serotype 5 (Ad5)-seropositive individuals who received the Merck recombinant Ad5 HIV-1 vaccine in the STEP study remains unclear. Here we show that baseline Ad5-specific neutralizing antibodies are not correlated with Ad5-specific T lymphocyte responses and that Ad5-seropositive subjects do not develop higher vector-specific cellular immune responses as compared with Ad5-seronegative subjects after vaccination. These findings challenge the hypothesis that activated Ad5-specific T lymphocytes were the cause of the potential enhanced HIV-1 susceptibility in the STEP study.
Nature medicine 09/2009; 15(8):873-5. DOI:10.1038/nm.1991 · 28.05 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Rare serotype and chimeric recombinant adenovirus (rAd) vectors that evade anti-Ad5 immunity are currently being evaluated as potential vaccine vectors for human immunodeficiency virus type 1 and other pathogens. We have recently reported that a heterologous rAd prime-boost regimen expressing simian immunodeficiency virus (SIV) Gag afforded durable partial immune control of an SIV challenge in rhesus monkeys. However, single-shot immunization may ultimately be preferable for global vaccine delivery. We therefore evaluated the immunogenicity and protective efficacy of a single immunization of chimeric rAd5 hexon hypervariable region 48 (rAd5HVR48) vectors expressing SIV Gag, Pol, Nef, and Env against a homologous SIV challenge in rhesus monkeys. Inclusion of Env resulted in improved control of peak and set point SIV RNA levels following challenge. In contrast, DNA vaccine priming did not further improve the protective efficacy of rAd5HVR48 vectors in this system.
Journal of Virology 07/2009; 83(18):9584-90. DOI:10.1128/JVI.00821-09 · 4.65 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A recombinant adenovirus serotype 5 (rAd5) vector-based vaccine for HIV-1 has recently failed in a phase 2b efficacy study in humans. Consistent with these results, preclinical studies have demonstrated that rAd5 vectors expressing simian immunodeficiency virus (SIV) Gag failed to reduce peak or setpoint viral loads after SIV challenge of rhesus monkeys (Macaca mulatta) that lacked the protective MHC class I allele Mamu-A*01 (ref. 3). Here we show that an improved T-cell-based vaccine regimen using two serologically distinct adenovirus vectors afforded substantially improved protective efficacy in this challenge model. In particular, a heterologous rAd26 prime/rAd5 boost vaccine regimen expressing SIV Gag elicited cellular immune responses with augmented magnitude, breadth and polyfunctionality as compared with the homologous rAd5 regimen. After SIV(MAC251) challenge, monkeys vaccinated with the rAd26/rAd5 regimen showed a 1.4 log reduction of peak and a 2.4 log reduction of setpoint viral loads as well as decreased AIDS-related mortality as compared with control animals. These data demonstrate that durable partial immune control of a pathogenic SIV challenge for more than 500 days can be achieved by a T-cell-based vaccine in Mamu-A*01-negative rhesus monkeys in the absence of a homologous Env antigen. These findings have important implications for the development of next-generation T-cell-based vaccine candidates for HIV-1.
[Show abstract][Hide abstract] ABSTRACT: A critical goal of vaccine development for a wide variety of pathogens is the induction of potent and durable mucosal immunity. However, it has been assumed that this goal would be difficult to achieve by systemic vaccination due to the anatomic and functional distinctness of the systemic and mucosal immune systems and the resultant compartmentalization of immune responses. In this study, we show that Ag-specific CD8(+) T lymphocytes traffic efficiently to mucosal surfaces following systemic vaccination. Intramuscular immunization with recombinant adenovirus (rAd) vector-based vaccines expressing SIV Gag resulted in potent, durable, and functional CD8(+) T lymphocyte responses at multiple mucosal effector sites in both mice and rhesus monkeys. In adoptive transfer studies in mice, vaccine-elicited systemic CD8(+) T lymphocytes exhibited phenotypic plasticity, up-regulated mucosal homing integrins and chemokine receptors, and trafficked rapidly to mucosal surfaces. Moreover, the migration of systemic CD8(+) T lymphocytes to mucosal compartments accounted for the vast majority of Ag-specific mucosal CD8(+) T lymphocytes induced by systemic vaccination. Thus, i.m. vaccination can overcome immune compartmentalization and generate robust mucosal CD8(+) T lymphocyte memory. These data demonstrate that the systemic and mucosal immune systems are highly coordinated following vaccination.
The Journal of Immunology 10/2008; 181(6):4188-98. DOI:10.4049/jimmunol.181.6.4188 · 5.36 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In vivo electroporation (EP) has been shown to augment the immunogenicity of plasmid DNA vaccines, but its mechanism of action has not been fully characterized. In this study, we show that in vivo EP augmented cellular and humoral immune responses to a human immunodeficiency virus type 1 Env DNA vaccine in mice and allowed a 10-fold reduction in vaccine dose. This enhancement was durable for over 6 months, and re-exposure to antigen resulted in anamnestic effector and central memory CD8(+) T-lymphocyte responses. Interestingly, in vivo EP also recruited large mixed cellular inflammatory infiltrates to the site of inoculation. These infiltrates contained 45-fold-increased numbers of macrophages and 77-fold-increased numbers of dendritic cells as well as 2- to 6-fold-increased numbers of B and T lymphocytes compared to infiltrates following DNA vaccination alone. These data suggest that recruiting inflammatory cells, including antigen-presenting cells (APCs), to the site of antigen production substantially improves the immunogenicity of DNA vaccines. Combining in vivo EP with plasmid chemokine adjuvants that similarly recruited APCs to the injection site, however, did not result in synergy.
Journal of Virology 07/2008; 82(11):5643-9. DOI:10.1128/JVI.02564-07 · 4.65 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Recombinant adenovirus serotype 5 (rAd5) vaccine vectors for human immunodeficiency virus type 1 (HIV-1) and other pathogens have been shown to elicit antigen-specific cellular immune responses. Rare serotype rAd vectors have also been constructed to circumvent preexisting anti-Ad5 immunity and to facilitate the development of novel heterologous rAd prime-boost regimens. Here we show that rAd5, rAd26, and rAd48 vectors elicit qualitatively distinct phenotypes of cellular immune responses in rhesus monkeys and can be combined as potent heterologous prime-boost vaccine regimens. While rAd5-Gag induced primarily gamma interferon-positive (IFN-gamma(+)) and IFN-gamma(+)/tumor necrosis factor alpha(+) (TNF-alpha(+)) T-lymphocyte responses, rAd26-Gag and rAd48-Gag induced higher proportions of interleukin-2(+) (IL-2(+)) and polyfunctional IFN-gamma(+)/TNF-alpha(+)/IL-2(+) T-lymphocyte responses. Priming with the rare serotype rAd vectors proved remarkably effective for subsequent boosting with rAd5 vectors. These data demonstrate that the rare serotype rAd vectors elicited T-lymphocyte responses that were phenotypically distinct from those elicited by rAd5 vectors and suggest the functional relevance of polyfunctional CD8(+) and CD4(+) T-lymphocyte responses. Moreover, qualitative differences in cellular immune responses may prove critical in determining the overall potency of heterologous rAd prime-boost regimens.
Journal of Virology 06/2008; 82(10):4844-52. DOI:10.1128/JVI.02616-07 · 4.65 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The purpose of the present study was to correlate the in vitro level of HIV Env expression by recombinant modified vaccinia virus Ankara (rMVA) with immunogenicity in mice. A 5-fold difference in Env synthesis was achieved at the translational level by the presence or absence of an out-of-frame initiation codon upstream of the env gene. This perturbation had no effect on the size or processing of Env. In contrast to the variation in Env synthesis, the rMVAs produced similar amounts of HIV Gag, which were expressed from identical cassettes. Mice immunized with the higher Env expressing rMVAs had about 15-fold higher titers of Env antibodies and several fold higher frequencies of Env-specific CD8+ and CD4+ T cells than mice immunized with the low expresser. The greater immune response achieved by high expression was maintained over a 100-fold dose range. Importantly, enhanced Env immune responses did not come at the expense of lower Gag T cell responses. These data suggest that for high immunogenicity, rMVAs should be engineered to produce the most recombinant protein that can be achieved without compromising the growth and stability of the rMVA.