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Induction or Type 1 Immune Responses to SIV by IFN-Gamma.

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Final rept. 1 Jun 95-30 May 99

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We report the results of our experiment to address problems associated with efficacy of subunit vaccines and safety of live attenuated vaccines by inducing a Type 1 immune response using IFN-gamma Rhesus macaques were vaccinated with either a recombinant vaccinia virus rVV vaccine expressing the SIV gag, gp160, nef, and human lFN-gamma genes or one expressing only the three SlV proteins. The animals were given three inoculations of rVVs 0, 8, 26 weeks, boosted with baculovirus-expressed gag and gp 160 61 weeks and then inoculated with a high dose 100 TCID50 of a live attenuated SIV vaccine, SIV 63 weeks. All animals had low to undetectable virus titers by 14 weeks post-inoculation. Fifty weeks post-inoculation, the animals were challenged with 10 TCIDS0 of SIVmac251. Twelve weeks after the challenge, 80 of the vaccinated animals have low to undetectable virus loads whereas the naive controls have high virus loads decreasing CD4 cell counts and one animal has early signs of SAIDS. Monkeys that received the rVV expressing human IFN-gamma have lower but not statistically significant average virus loads and CD4 cell counts. These results show that this vaccine regime is effective in decreasing virus load but not infection with a high dose intravenous challenge virus.

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  • Anatomy and Physiology
  • Medicine and Medical Research

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