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Superinfection of HIV-2-preinfected macaques after rectal exposure to a primary isolate of SIVmac251.
Wakrim L; Le Grand R; Vaslin B; Cheret A; Matheux F; Theodoro F; Roques
January 30, 1997
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