Critical role for Env as well as Gag-Pol in control of a simian-human immunodeficiency virus 89.6P challenge by a DNA prime/recombinant modified vaccinia virus Ankara vaccine

J Virol. 2002 Jun;76(12):6138-46. doi: 10.1128/jvi.76.12.6138-6146.2002.


Cellular immune responses against epitopes in conserved Gag and Pol sequences of human immunodeficiency virus type 1 have become popular targets for candidate AIDS vaccines. Recently, we used a simian-human immunodeficiency virus model (SHIV 89.6P) with macaques to demonstrate the control of a pathogenic mucosal challenge by priming with Gag-Pol-Env-expressing DNA and boosting with Gag-Pol-Env-expressing recombinant modified vaccinia virus Ankara (rMVA). Here we tested Gag-Pol DNA priming and Gag-Pol rMVA boosting to evaluate the contribution of anti-Env immune responses to viral control. The Gag-Pol vaccine raised frequencies of Gag-specific T cells similar to those raised by the Gag-Pol-Env vaccine. Following challenge, these rapidly expanded to counter the challenge infection. Despite this, the control of the SHIV 89.6P challenge was delayed and inconsistent in the Gag-Pol-vaccinated group and all of the animals underwent severe and, in most cases, sustained loss of CD4(+) cells. Interestingly, most of the CD4(+) cells that were lost in the Gag-Pol-vaccinated group were uninfected cells. We suggest that the rapid appearance of binding antibody for Env in Gag-Pol-Env-vaccinated animals helped protect uninfected CD4(+) cells from Env-induced apoptosis. Our results highlight the importance of immune responses to Env, as well as to Gag-Pol, in the control of immunodeficiency virus challenges and the protection of CD4(+) cells.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • AIDS Vaccines / immunology*
  • Animals
  • CD4-Positive T-Lymphocytes / immunology
  • Fusion Proteins, gag-pol / immunology*
  • Gene Products, env / immunology*
  • HIV / immunology
  • HIV Antibodies / blood
  • HIV Infections / prevention & control*
  • Humans
  • Macaca mulatta
  • Simian Acquired Immunodeficiency Syndrome / prevention & control*
  • Simian Immunodeficiency Virus / immunology
  • Vaccination
  • Vaccines, DNA / immunology*
  • Vaccinia virus / genetics
  • Vaccinia virus / immunology


  • AIDS Vaccines
  • Fusion Proteins, gag-pol
  • Gene Products, env
  • HIV Antibodies
  • Vaccines, DNA