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Heterologous envelope immunogens contribute to AIDS vaccine protection in rhesus monkeys.

ABSTRACT: Because a strategy to elicit broadly neutralizing anti-human immunodeficiency virus type 1 (HIV-1) antibodies has not yet been found, the role of an Env immunogen in HIV-1 vaccine candidates remains undefined. We sought to determine whether an HIV-1 Env immunogen genetically disparate from the Env of the challenge virus can contribute to protective immunity. We vaccinated Indian-origin rhesus monkeys with Gag-Pol-Nef immunogens, alone or in combination with Env immunogens that were either matched or mismatched with the challenge virus. These animals were then challenged with a pathogenic simian-human immunodeficiency virus. The vaccine regimen included a plasmid DNA prime and replication-defective adenoviral vector boost. Vaccine regimens that included the matched or mismatched Env immunogens conferred better protection against CD4(+) T-lymphocyte loss than that seen with comparable regimens that did not include Env immunogens. This increment in protective immunity was associated with anamnestic Env-specific cellular immunity that developed in the early days following viral challenge. These data suggest that T-lymphocyte immunity to Env can broaden the protective cellular immune response to HIV despite significant sequence diversity of the strains of the Env immunogens and can contribute to immune protection in this AIDS vaccine model.

SUBMITTER: Letvin NL

PROVIDER: S-EPMC434100 | biostudies-literature | 2004 Jul

REPOSITORIES: biostudies-literature

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Heterologous envelope immunogens contribute to AIDS vaccine protection in rhesus monkeys.

Letvin Norman L NL Huang Yue Y Chakrabarti Bimal K BK Xu Ling L Seaman Michael S MS Beaudry Kristin K Korioth-Schmitz Birgit B Yu Faye F Rohne Daniela D Martin Kristi L KL Miura Ayako A Kong Wing-Pui WP Yang Zhi-Yong ZY Gelman Rebecca S RS Golubeva Olga G OG Montefiori David C DC Mascola John R JR Nabel Gary J GJ

Journal of virology 20040701 14

Because a strategy to elicit broadly neutralizing anti-human immunodeficiency virus type 1 (HIV-1) antibodies has not yet been found, the role of an Env immunogen in HIV-1 vaccine candidates remains undefined. We sought to determine whether an HIV-1 Env immunogen genetically disparate from the Env of the challenge virus can contribute to protective immunity. We vaccinated Indian-origin rhesus monkeys with Gag-Pol-Nef immunogens, alone or in combination with Env immunogens that were either matche ...[more]

PMID: 15220422

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Project description:BackgroundZika virus (ZIKV; Flaviviridae, Flavivirus) was declared a public health emergency of international concern by the World Health Organization (WHO) in February 2016, because of the evidence linking infection with ZIKV to neurological complications, such as Guillain-Barre Syndrome in adults and congenital birth defects including microcephaly in the developing fetus. Because development of a ZIKV vaccine is a top research priority and because the genetic and antigenic variability of many RNA viruses limits the effectiveness of vaccines, assessing whether immunity elicited against one ZIKV strain is sufficient to confer broad protection against all ZIKV strains is critical. Recently, in vitro studies demonstrated that ZIKV likely circulates as a single serotype. Here, we demonstrate that immunity elicited by African lineage ZIKV protects rhesus macaques against subsequent infection with Asian lineage ZIKV.Methodology/principal findingsUsing our recently developed rhesus macaque model of ZIKV infection, we report that the prototypical ZIKV strain MR766 productively infects macaques, and that immunity elicited by MR766 protects macaques against heterologous Asian ZIKV. Furthermore, using next generation deep sequencing, we found in vivo restoration of a putative N-linked glycosylation site upon replication in macaques that is absent in numerous MR766 strains that are widely being used by the research community. This reversion highlights the importance of carefully examining the sequence composition of all viral stocks as well as understanding how passage history may alter a virus from its original form.Conclusions/significanceAn effective ZIKV vaccine is needed to prevent infection-associated fetal abnormalities. Macaques whose immune responses were primed by infection with East African ZIKV were completely protected from detectable viremia when subsequently rechallenged with heterologous Asian ZIKV. Therefore, these data suggest that immunogen selection is unlikely to adversely affect the breadth of vaccine protection, i.e., any Asian ZIKV immunogen that protects against homologous challenge will likely confer protection against all other Asian ZIKV strains.

Project description:Lentiviral envelope (Env) antigenic variation and associated immune evasion present major obstacles to vaccine development. The concept that Env is a critical determinant for vaccine efficacy is well accepted, however defined correlates of protection associated with Env variation have yet to be determined. We reported an attenuated equine infectious anemia virus (EIAV) vaccine study that directly examined the effect of lentiviral Env sequence variation on vaccine efficacy. The study identified a significant, inverse, linear correlation between vaccine efficacy and increasing divergence of the challenge virus Env gp90 protein compared to the vaccine virus gp90. The report demonstrated approximately 100% protection of immunized ponies from disease after challenge by virus with a homologous gp90 (EV0), and roughly 40% protection against challenge by virus (EV13) with a gp90 13% divergent from the vaccine strain. In the current study we examine whether the protection observed when challenging with the EV0 strain could be conferred to animals via chimeric challenge viruses between the EV0 and EV13 strains, allowing for mapping of protection to specific Env sequences. Viruses containing the EV13 proviral backbone and selected domains of the EV0 gp90 were constructed and in vitro and in vivo infectivity examined. Vaccine efficacy studies indicated that homology between the vaccine strain gp90 and the N-terminus of the challenge strain gp90 was capable of inducing immunity that resulted in significantly lower levels of post-challenge virus and significantly delayed the onset of disease. However, a homologous N-terminal region alone inserted in the EV13 backbone could not impart the 100% protection observed with the EV0 strain. Data presented here denote the complicated and potentially contradictory relationship between in vitro virulence and in vivo pathogenicity. The study highlights the importance of structural conformation for immunogens and emphasizes the need for antibody binding, not neutralizing, assays that correlate with vaccine protection.

Project description:Lentiviral Envelope (Env) antigenic variation and related immune evasion present major hurdles to effective vaccine development. Centralized Env immunogens that minimize the genetic distance between vaccine proteins and circulating viral isolates are an area of increasing study in HIV vaccinology. To date, the efficacy of centralized immunogens has not been evaluated in the context of an animal model that could provide both immunogenicity and protective efficacy data. We previously reported on a live-attenuated (attenuated) equine infectious anemia (EIAV) virus vaccine, which provides 100% protection from disease after virulent, homologous, virus challenge. Further, protective efficacy demonstrated a significant, inverse, linear relationship between EIAV Env divergence and protection from disease when vaccinates were challenged with viral strains of increasing Env divergence from the vaccine strain Env. Here, we sought to comprehensively examine the protective efficacy of centralized immunogens in our attenuated vaccine platform. We developed, constructed, and extensively tested a consensus Env, which in a virulent proviral backbone generated a fully replication-competent pathogenic virus, and compared this consensus Env to an ancestral Env in our attenuated proviral backbone. A polyvalent attenuated vaccine was established for comparison to the centralized vaccines. Additionally, an engineered quasispecies challenge model was created for rigorous assessment of protective efficacy. Twenty-four EIAV-naïve animals were vaccinated and challenged along with six-control animals six months post-second inoculation. Pre-challenge data indicated the consensus Env was more broadly immunogenic than the Env of the other attenuated vaccines. However, challenge data demonstrated a significant increase in protective efficacy of the polyvalent vaccine. These findings reveal, for the first time, a consensus Env immunogen that generated a fully-functional, replication-competent lentivirus, which when experimentally evaluated, demonstrated broader immunogenicity that does not equate to higher protective efficacy.

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Heterologous envelope immunogens contribute to AIDS vaccine protection in rhesus monkeys.

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Heterologous envelope immunogens contribute to AIDS vaccine protection in rhesus monkeys.

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