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Bricault, Christine

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Bricault

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Christine

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Bricault, Christine
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    Vaccine Protection Against Zika Virus from Brazil
    (2016) Larocca, Rafael; Abbink, Peter; Peron, Jean Pierre S.; de A. Zanotto, Paolo M.; Iampietro, M. Justin; Badamchi-Zadeh, Alexander; Boyd, Michael; Ng’ang’a, David; Kirilova, Marinela; Nityanandam, Ramya; Mercado, Noe B.; Li, Zhenfeng; Moseley, Edward T.; Bricault, Christine; Borducchi, Erica N.; Giglio, Patricia B.; Jetton, David; Neubauer, George; Nkolola, Joseph; Maxfield, Lori; De La Barrera, Rafael A.; Jarman, Richard G.; Eckels, Kenneth H.; Michael, Nelson L.; Thomas, Stephen J.; Barouch, Dan
    Zika virus (ZIKV) is a flavivirus that is responsible for an unprecedented current epidemic in Brazil and the Americas1,2. ZIKV has been causally associated with fetal microcephaly, intrauterine growth restriction, and other birth defects in both humans3–8 and mice9–11. The rapid development of a safe and effective ZIKV vaccine is a global health priority1,2, but very little is currently known about ZIKV immunology and mechanisms of immune protection. Here we show that a single immunization of a plasmid DNA vaccine or a purified inactivated virus vaccine provides complete protection in susceptible mice against challenge with a ZIKV outbreak strain from northeast Brazil. This ZIKV strain has recently been shown to cross the placenta and to induce fetal microcephaly and other congenital malformations in mice11. We produced DNA vaccines expressing full-length ZIKV pre-membrane and envelope (prM-Env) as well as a series of deletion mutants. The full-length prM-Env DNA vaccine, but not the deletion mutants, afforded complete protection against ZIKV as measured by absence of detectable viremia following challenge, and protective efficacy correlated with Env-specific antibody titers. Adoptive transfer of purified IgG from vaccinated mice conferred passive protection, and CD4 and CD8 T lymphocyte depletion in vaccinated mice did not abrogate protective efficacy. These data demonstrate that protection against ZIKV challenge can be achieved by single-shot subunit and inactivated virus vaccines in mice and that Env-specific antibody titers represent key immunologic correlates of protection. Our findings suggest that the development of a ZIKV vaccine for humans will likely be readily achievable.
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    Therapeutic Efficacy of Vectored PGT121 Gene Delivery in HIV-1-Infected Humanized Mice
    (American Society for Microbiology, 2018) Badamchi-Zadeh, Alexander; Tartaglia, Lawrence; Abbink, Peter; Bricault, Christine; Liu, Po-Ting; Boyd, Michael; Kirilova, Marinela; Mercado, Noe B.; Nanayakkara, Ovini S.; Vrbanac, Vladimir D.; Tager, Andrew M.; Larocca, Rafael; Seaman, Michael; Barouch, Dan
    ABSTRACT Broadly neutralizing antibodies (bNAbs) are being explored for HIV-1 prevention and cure strategies. However, administration of purified bNAbs poses challenges in resource-poor settings, where the HIV-1 disease burden is greatest. In vivo vector-based production of bNAbs represents an alternative strategy. We investigated adenovirus serotype 5 (Ad5) and adeno-associated virus serotype 1 (AAV1) vectors to deliver the HIV-1-specific bNAb PGT121 in wild-type and immunocompromised C57BL/6 mice as well as in HIV-1-infected bone marrow-liver-thymus (BLT) humanized mice. Ad5.PGT121 and AAV1.PGT121 produced functional antibody in vivo. Ad5.PGT121 produced PGT121 rapidly within 6 h, whereas AAV1.PGT121 produced detectable PGT121 in serum by 72 h. Serum PGT121 levels were rapidly reduced by the generation of anti-PGT121 antibodies in immunocompetent mice but were durably maintained in immunocompromised mice. In HIV-1-infected BLT humanized mice, Ad5.PGT121 resulted in a greater reduction of viral loads than did AAV1.PGT121. Ad5.PGT121 also led to more-sustained virologic control than purified PGT121 IgG. Ad5.PGT121 afforded more rapid, robust, and durable antiviral efficacy than AAV1.PGT121 and purified PGT121 IgG in HIV-1-infected humanized mice. Further evaluation of vector delivery of HIV-1 bNAbs is warranted, although approaches to prevent the generation of antiantibody responses may also be required. IMPORTANCE: Broadly neutralizing antibodies (bNAbs) are being explored for HIV-1 prevention and cure strategies, but delivery of purified antibodies may prove challenging. We investigated adenovirus serotype 5 (Ad5) and adeno-associated virus serotype 1 (AAV1) vectors to deliver the HIV-1-specific bNAb PGT121. Ad5.PGT121 afforded more rapid, robust, and durable antiviral efficacy than AAV1.PGT121 and purified PGT121 IgG in HIV-1-infected humanized mice.
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    Neutralizing Antibody Responses following Long-Term Vaccination with HIV-1 Env gp140 in Guinea Pigs
    (American Society for Microbiology, 2018) Bricault, Christine; Kovacs, James M.; Badamchi-Zadeh, Alexander; McKee, Krisha; Shields, Jennifer L.; Gunn, Bronwyn; Neubauer, George H.; Ghantous, Fadi; Jennings, Julia; Gillis, Lindsey; Perry, James; Nkolola, Joseph; Alter, Galit; Chen, Bing; Stephenson, Kathryn; Doria-Rose, Nicole; Mascola, John R.; Seaman, Michael; Barouch, Dan
    ABSTRACT A vaccination regimen capable of eliciting potent and broadly neutralizing antibodies (bNAbs) remains an unachieved goal of the HIV-1 vaccine field. Here, we report the immunogenicity of longitudinal prime/boost vaccination regimens with a panel of HIV-1 envelope (Env) gp140 protein immunogens over a period of 200 weeks in guinea pigs. We assessed vaccine regimens that included a monovalent clade C gp140 (C97ZA012 [C97]), a tetravalent regimen consisting of four clade C gp140s (C97ZA012, 459C, 405C, and 939C [4C]), and a tetravalent regimen consisting of clade A, B, C, and mosaic gp140s (92UG037, PVO.4, C97ZA012, and Mosaic 3.1, respectively [ABCM]). We found that the 4C and ABCM prime/boost regimens were capable of eliciting greater magnitude and breadth of binding antibody responses targeting variable loop 2 (V2) over time than the monovalent C97-only regimen. The longitudinal boosting regimen conducted over more than 2 years increased the magnitude of certain tier 1 NAb responses but did not increase the magnitude or breadth of heterologous tier 2 NAb responses. These data suggest that additional immunogen design strategies are needed to induce broad, high-titer tier 2 NAb responses. IMPORTANCE: The elicitation of potent, broadly neutralizing antibodies (bNAbs) remains an elusive goal for the HIV-1 vaccine field. In this study, we explored the use of a long-term vaccination regimen with different immunogens to determine if we could elicit bNAbs in guinea pigs. We found that longitudinal boosting over more than 2 years increased tier 1 NAb responses but did not increase the magnitude and breadth of tier 2 NAb responses. These data suggest that additional immunogen designs and vaccination strategies will be necessary to induce broad tier 2 NAb responses.
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    Immunogenicity and Cross-Reactivity of Rhesus Adenoviral Vectors
    (American Society for Microbiology, 2018) Iampietro, M. Justin; Larocca, Rafael; Provine, Nicholas M.; Abbink, Peter; Kang, Zi Han; Bricault, Christine; Barouch, Dan
    ABSTRACT Adenovirus (Ad) vectors are being investigated as vaccine candidates, but baseline antivector immunity exists in human populations to both human Ad (HuAd) and chimpanzee Ad (ChAd) vectors. In this study, we investigated the immunogenicity and cross-reactivity of a panel of recently described rhesus adenoviral (RhAd) vectors. RhAd vectors elicited T cells with low exhaustion markers and robust anamnestic potential. Moreover, RhAd vector immunogenicity was unaffected by high levels of preexisting anti-HuAd immunity. Both HuAd/RhAd and RhAd/RhAd prime-boost vaccine regimens were highly immunogenic, despite a degree of cross-reactive neutralizing antibodies (NAbs) between phylogenetically related RhAd vectors. We observed extensive vector-specific cross-reactive CD4 T cell responses and more limited CD8 T cell responses between RhAd and HuAd vectors, but the impact of vector-specific cellular responses was far less than that of vector-specific NAbs. These data suggest the potential utility of RhAd vectors and define novel heterologous prime-boost strategies for vaccine development. IMPORTANCE: To date, most adenoviral vectors developed for vaccination have been HuAds from species B, C, D, and E, and human populations display moderate to high levels of preexisting immunity. There is a clinical need for new adenoviral vectors that are not hindered by preexisting immunity. Moreover, the development of RhAd vector vaccines expands our ability to vaccinate against multiple pathogens in a population that may have received other HuAd or ChAd vectors. We evaluated the immunogenicity and cross-reactivity of RhAd vectors, which belong to the poorly described adenovirus species G. These vectors induced robust cellular and humoral immune responses and were not hampered by preexisting anti-HuAd vector immunity. Such properties make RhAd vectors attractive as potential vaccine vectors.
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    Antibody Responses After Analytic Treatment Interruption in Human Immunodeficiency Virus-1-Infected Individuals on Early Initiated Antiretroviral Therapy
    (Oxford University Press, 2016) Stephenson, Kathryn; Neubauer, George H.; Bricault, Christine; Shields, Jennifer; Bayne, Madeleine; Reimer, Ulf; Pawlowski, Nikolaus; Knaute, Tobias; Zerweck, Johannes; Seaman, Michael; Rosenberg, Eric; Barouch, Dan
    The examination of antibody responses in human immunodeficiency virus (HIV)-1-infected individuals in the setting of antiretroviral treatment (ART) interruption can provide insight into the evolution of antibody responses during viral rebound. In this study, we assessed antibody responses in 20 subjects in AIDS Clinical Trials Group A5187, wherein subjects were treated with antiretroviral therapy during acute/early HIV-1 infection, underwent analytic treatment interruption, and subsequently demonstrated viral rebound. Our data suggest that early initiation of ART arrests the maturation of HIV-1-specific antibody responses, preventing epitope diversification of antibody binding and the development of functional neutralizing capacity. Antibody responses do not appear permanently blunted, however, because viral rebound triggered the resumption of antibody maturation in our study. We also found that antibody responses measured by these assays did not predict imminent viral rebound. These data have important implications for the HIV-1 vaccine and eradication fields.
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    Transient CD4+ T Cell Depletion Results in Delayed Development of Functional Vaccine-Elicited Antibody Responses
    (American Society for Microbiology, 2016) Provine, Nicholas M.; Badamchi-Zadeh, Alexander; Bricault, Christine; Penaloza-MacMaster, Pablo; Larocca, Rafael A.; Borducchi, Erica N.; Seaman, Michael; Barouch, Dan
    ABSTRACT We have recently demonstrated that CD4+ T cell help is required at the time of adenovirus (Ad) vector immunization for the development of functional CD8+ T cell responses, but the temporal requirement for CD4+ T cell help for the induction of antibody responses remains unclear. Here we demonstrate that induction of antibody responses in C57BL/6 mice can occur at a time displaced from the time of Ad vector immunization by depletion of CD4+ T cells. Transient depletion of CD4+ T cells at the time of immunization delays the development of antigen-specific antibody responses but does not permanently impair their development or induce tolerance against the transgene. Upon CD4+ T cell recovery, transgene-specific serum IgG antibody titers develop and reach a concentration equivalent to that in undepleted control animals. These delayed antibody responses exhibit no functional defects with regard to isotype, functional avidity, expansion after boosting immunization, or the capacity to neutralize a simian immunodeficiency virus (SIV) Env-expressing pseudovirus. The development of this delayed transgene-specific antibody response is temporally linked to the expansion of de novo antigen-specific CD4+ T cell responses, which develop after transient depletion of CD4+ T cells. These data demonstrate that functional vaccine-elicited antibody responses can be induced even if CD4+ T cell help is provided at a time markedly separated from the time of vaccination. IMPORTANCE: CD4+ T cells have a critical role in providing positive help signals to B cells, which promote robust antibody responses. The paradigm is that helper signals must be provided immediately upon antigen exposure, and their absence results in tolerance against the antigen. Here we demonstrate that, in contrast to the current model that the absence of CD4+ T cell help at priming results in long-term antibody nonresponsiveness, antibody responses can be induced by adenovirus vector immunization or alum-adjuvanted protein immunization even if CD4+ T cell help is not provided until >1 month after immunization. These data demonstrate that the time when CD4+ T cell help signals must be provided is more dynamic and flexible than previously appreciated. These data suggest that augmentation of CD4+ T cell helper function even after the time of vaccination can enhance vaccine-elicited antibody responses and thereby potentially enhance the immunogenicity of vaccines in immunocompromised individuals.
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    Multivalent Vaccination Strategies With Novel HIV-1 Trimeric Envelope Proteins Elicit Improved Neutralizing Antibody Responses Compared to Monovalent Vaccination Regimens
    (2016-04-05) Bricault, Christine; Alter, Galit; Gabuzda, Dana; Lu, Shan
    Elicitation of neutralizing antibodies (NAbs) remains a major goal in the generation of a successful vaccine against human immunodeficiency virus type 1 (HIV-1). One of the major obstacles in generating such NAbs is the vast sequence diversity of their target, the HIV-1 envelope (Env) protein. This dissertation will describe multiple vaccination strategies utilizing a soluble form of Env (gp140) to address the sequence diversity of HIV-1 Env and to improve the NAb responses elicited through vaccination in the guinea pig model. A bioinformatically optimized mosaic gp140, designed as a single sequence to cover global HIV-1 sequence diversity, was utilized in combination with a clade C gp140, resulting in a complementary repertoire of NAbs when compared to vaccination with each single protein. Additionally, a quadrivalent mixture of four novel clade C gp140s with distinct antigenic properties was found to elicit a greater magnitude of NAbs when compared to any single protein in the mixture. Furthermore, longitudinal, heterologous prime/boost vaccination regimens resulted in binding antibodies to a greater number of distinct sequences within a single epitope of variable loop 2, and NAb of a greater magnitude, than a homologous prime/boost regimen. Finally, a panel of rationally designed variable loop 2 and 3 sequence modified trimers was designed. When utilized in a mixture, the variable loop 2 modified trimers elicited a greater magnitude and breadth of NAbs than the single, unmodified wild type protein alone. These data show that multivalent vaccination strategies with HIV-1 Env trimers result in improved NAb responses compared to single Env protein vaccinations and may help to guide the development of future vaccination regimens.