Differential distribution of antibodies to different viruses in young animals in the free-ranging rhesus macaques of Cayo Santiago.

BACKGROUND: The breeding colony of free-ranging rhesus macaques was established in 1938 in Cayo Santiago (CS) with animals collected in northern India. The seroprevalence to cercopithecine herpesvirus type 1 (B virus) and simian retroviruses has been studied previously. RESULTS: This is the first report on the seropositivity to different viruses using samples collected shortly after removing animals (n = 245) from CS. All samples were negative for measles, simian immunodeficiency virus and simian type D retroviruses. The overall prevalence of antibodies was around 50% for simian T-lymphotropic virus I (STLV-I). For B virus, the prevalence was 38%. CONCLUSIONS: Data obtained showed marked differences in the antibody distribution to B virus and STLV-I within the free-ranging colony of rhesus macaques. Implication of these data for the Specific Pathogen Free program at the Caribbean Primate Research Center are also discussed.

Protection by SIV VLP DNA prime/protein boost following mucosal SIV challenge is markedly enhanced by IL-12/GM-CSF co-administration.

The ever increasing number of people infected by human immunodeficiency virus (HIV) throughout the world renders the development of effective vaccines an urgent priority. Herein, we report on an attempt to induce and enhance antiviral responses using a deoxyribonucleic acid (DNA) prime/virus-like particles (VLP) protein boost strategy adjuvanted with interleukin (IL)-12/GM-CSF in rhesus macaques challenged with simian immunodeficiency virus (SIV). Thus, groups of monkeys were administered three consecutive doses of pVecB7 a plasmid expressing VLP with or without plasmids expressing IL-12 and GM-CSF at weeks 0, 13 and 26. The VLP boost was administered at week 39 with or without IL-12. All monkeys were challenged intrarectally with SIVsmE660 2 months following the protein boost. All except one immunized monkey became infected. While all immunized monkeys showed a marked reduction of acute viral peaks, reduction of viral load set points was only achieved in groups whose prime-boost immunizations were supplemented with IL-12/GM-CSF (prime) and/or with IL-12 (boost). Control of viremia correlated with lack of disease progression and survival. Detection of virus in rectal washes at 1 year post-challenge was only successful in monkeys whose immunizations did not include cytokine adjuvant, but these loads did not correlate with plasma viral loads. In summary, use of IL-12 and/or GM-CSF was shown to provide significant differences in the outcome of SIV challenge of prime/boost immunized monkeys.