Vaccination with Gag, Vif, and Nef gene fragments affords partial control of viral replication after mucosal challenge with SIVmac239. Academic Article uri icon

Overview

MeSH

  • Animals
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Histocompatibility Antigens Class I
  • Humans
  • Immunity, Cellular
  • Macaca mulatta
  • Male
  • Mice
  • Simian immunodeficiency virus
  • Vaccination

MeSH Major

  • Gene Products, gag
  • Gene Products, nef
  • Gene Products, vif
  • Genetic Vectors
  • Simian Acquired Immunodeficiency Syndrome
  • Vaccines, Synthetic
  • Virus Replication

abstract

  • Broadly targeted cellular immune responses are thought to be important for controlling replication of human and simian immunodeficiency viruses (HIV and SIV). However, eliciting such responses by vaccination is complicated by immunodominance, the preferential targeting of only a few of the many possible epitopes of a given antigen. This phenomenon may be due to the coexpression of dominant and subdominant epitopes by the same antigen-presenting cell and may be overcome by distributing these sequences among several different vaccine constructs. Accordingly, we tested whether vaccinating rhesus macaques with "minigenes" encoding fragments of Gag, Vif, and Nef resulted in broadened cellular responses capable of controlling SIV replication. We delivered these minigenes through combinations of recombinant Mycobacterium bovis BCG (rBCG), electroporated recombinant DNA (rDNA) along with an interleukin-12 (IL-12)-expressing plasmid (EP rDNA plus pIL-12), yellow fever vaccine virus 17D (rYF17D), and recombinant adenovirus serotype 5 (rAd5). Although priming with EP rDNA plus pIL-12 increased the breadth of vaccine-induced T-cell responses, this effect was likely due to the improved antigen delivery afforded by electroporation rather than modulation of immunodominance. Indeed, Mamu-A*01(+) vaccinees mounted CD8(+) T cells directed against only one subdominant epitope, regardless of the vaccination regimen. After challenge with SIVmac239, vaccine efficacy was limited to a modest reduction in set point in some of the groups and did not correlate with standard T-cell measurements. These findings suggest that broad T-cell responses elicited by conventional vectors may not be sufficient to substantially contain AIDS virus replication. Immunodominance poses a major obstacle to the generation of broadly targeted, HIV-specific cellular responses by vaccination. Here we attempted to circumvent this phenomenon and thereby broaden the repertoire of SIV-specific cellular responses by vaccinating rhesus macaques with minigenes encoding fragments of Gag, Vif, and Nef. In contrast to previous mouse studies, this strategy appeared to minimally affect monkey CD8(+) T-cell immundominance hierarchies, as seen by the detection of only one subdominant epitope in Mamu-A*01(+) vaccinees. This finding underscores the difficulty of inducing subdominant CD8(+) T cells by vaccination and demonstrates that strategies other than gene fragmentation may be required to significantly alter immunodominance in primates. Although some of the regimens tested here were extremely immunogenic, vaccine efficacy was limited to a modest reduction in set point viremia after challenge with SIVmac239. No correlates of protection were identified. These results reinforce the notion that vaccine immunogenicity does not predict control of AIDS virus replication. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

publication date

  • July 2014

has subject area

  • Animals
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Gene Products, gag
  • Gene Products, nef
  • Gene Products, vif
  • Genetic Vectors
  • Histocompatibility Antigens Class I
  • Humans
  • Immunity, Cellular
  • Macaca mulatta
  • Male
  • Mice
  • Simian Acquired Immunodeficiency Syndrome
  • Simian immunodeficiency virus
  • Vaccination
  • Vaccines, Synthetic
  • Virus Replication

Research

keywords

  • Journal Article

Identity

Language

  • eng

PubMed Central ID

  • PMC4054456

Digital Object Identifier (DOI)

  • 10.1128/JVI.00601-14

PubMed ID

  • 24741098

Additional Document Info

start page

  • 7493

end page

  • 7516

volume

  • 88

number

  • 13