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Superinfection of HIV-2-preinfected macaques after rectal exposure to a primary isolate of SIVmac251.


Int Conf AIDS. 1996 Jul 7-12;11(2):11 (abstract no. We.A.284). Unique

Objectives: To test the potential vaccine effect of a weakly pathogenic HIV-2 isolate against the superinfection after an intrarectal inoculation with a pathogenic SIVmac251 isolate. Method: We intrarectally challenged six HIV-2-preinfected rhesus macaques with 10 AID50 of a pathogenic isolate of SIVmac251. These monkeys have been intravenously infected with HIV-2 ROD isolate five years ago. The outcome of this atraumatic challenge was monitored by serological and virological assays. For the PCR analysis, two nested-sets of oligonucleotide primers specific for env and pol regions of SIV mac251 and two nested sets of oligonucleotide primers specific for gag and pol regions of HIV-2 ROD were used. Results: After HIV-2 inoculation, virus was isolated from all these macaques at several time points, but at the time of SIV challenge none of these HIV-2 infected animals was positive for virus isolation, p27-Gag antigenemia or HIV-2 provirus detection in PBMCs or peripheral lymph nodes. However, all monkeys exhibited anti-HIV-2 antibody titers ranging from 102 to 103. Neutralizing antibodies against the challenge SIV strain were also detected in two animals; titers were respectively 101.7 and 102. After rectal exposure to SIV mac251, five of the six HIV-2-preinfected macaques were superinfected. SIV mac251 DNA sequences were detected repeatedly in the PBMCs of the five superinfected animals and the two controls, whereas no HIV-2 provirus was detected for 14 months after challenge. Moreover, both the 5 superinfected and the control monkeys exhibited a decline in CD4+ lymphocyte cells and one superinfected macaque died 15 weeks post SIV challenge from AIDS-like disease. The one monkey that resisted superinfection was negative for all SIV infection criteria. Conclusion: Intravenous inoculation of rhesus macaques with a weakly pathogenic HIV-2 isolate failed to confer protection in 5 of 6 animals against superinfection with a pathogenic closely related SIV mac251 isolate. Only one animal that exhibited the highest titers of whole IgG and cross-neutralizing anti-SIV antibodies at the day of SIV challenge was completely protected from superinfection. No protection from the progression of disease was evidenced in the 5 superinfected monkeys.

*HIV-2/IMMUNOLOGY *Retroviridae Proteins/IMMUNOLOGY *Simian Acquired Immunodeficiency Syndrome/PREVENTION & CONTROL *SIV/IMMUNOLOGY *Vaccines


Information in this article was accurate in January 30, 1997. The state of the art may have changed since the publication date. This material is designed to support, not replace, the relationship that exists between you and your doctor. Always discuss treatment options with a doctor who specializes in treating HIV.