SHIV infection protects against heterologous pathogenic SHIV challenge in macaques: a gold-standard for HIV-1 vaccine development?
ABSTRACT A current debate in the HIV-1 vaccine field concerns the ability of an immunodeficiency virus to elicit a protective response. One argument is that HIV-1 superinfections are frequent in healthy individuals, because virus evades conventional immune surveillance, a serious obstacle to vaccine design. The opposing argument is that protection from superinfection is significant, reflecting a robust immune response that might be harnessed by vaccination to prevent disease. In an experiment designed to address the debate, two macaques received an I.V. inoculation with SHIV KU-1-d (a derivative of SHIV KU-1) and were rested for >10 months. Infection elicited diverse neutralizing antibody activities in both animals. Animals were then exposed to SHIV 89.6P (I.V.), a virus carrying a heterologous envelope protein relative to the vaccine strain. Infection was monitored by viral load and CD4+ T-cell measurements. All control animals were infected and most succumbed to disease. In contrast, protection from superinfection was statistically significant in test monkeys; one animal showed no evidence of superinfection at any time point and the second showed evidence of virus at only one time point over a 6-month observation period. Neither animal showed signs of disease. Perhaps this protective state may serve as a 'gold-standard' for HIV-1 vaccine development, as a similar degree of protection against immunodeficiency virus infections in humans would be much desired.
New England Journal of Medicine 09/2008; 359(9):888-90. · 53.30 Impact Factor
Article: Human neutralizing monoclonal antibodies of the IgG1 subtype protect against mucosal simian-human immunodeficiency virus infection.[show abstract] [hide abstract]
ABSTRACT: Although maternal human immunodeficiency virus type 1 (HIV-1) transmission occurs during gestation, intrapartum and postpartum (by breast-feeding), 50-70% of all infected children seem to acquire HIV-1 shortly before or during delivery. Epidemiological evidence indicates that mucosal exposure is an important aspect of intrapartum HIV transmission. A simian immunodeficiency virus (SIV) macaque model has been developed that mimics the mucosal exposure that can occur during intrapartum HIV-1 transmission. To develop immunoprophylaxis against intrapartum HIV-1 transmission, we used SHIV-vpu+ (refs. 5,6), a chimeric simian-human virus that encodes the env gene of HIV-IIIB. Several combinations of human monoclonal antibodies against HIV-1 have been identified that neutralize SHIV-vpu+ completely in vitro through synergistic interaction. Here, we treated four pregnant macaques with a triple combination of the human IgG1 monoclonal antibodies F105, 2G12 and 2F5. All four macaques were protected against intravenous SHIV-vpu+ challenge after delivery. The infants received monoclonal antibodies after birth and were challenged orally with SHIV-vpu+ shortly thereafter. We found no evidence of infection in any infant during 6 months of follow-up. This demonstrates that IgG1 monoclonal antibodies protect against mucosal lentivirus challenge in neonates. We conclude that epitopes recognized by the three monoclonal antibodies are important determinants for achieving substantial protection, thus providing a rational basis for AIDS vaccine development.Nature Medicine 03/2000; 6(2):200-6. · 22.46 Impact Factor
Article: Resistance to superinfection by a vigorously replicating, uncloned stock of simian immunodeficiency virus (SIVmac251) stimulates replication of a live attenuated virus vaccine (SIVmacC8).[show abstract] [hide abstract]
ABSTRACT: Vaccination with live attenuated simian immunodeficiency virus (SIVmacC8) confers potent, reproducible protection against homologous wild-type virus challenge (SIVmacJ5). The ability of SIVmacC8 to confer resistance to superinfection with an uncloned ex vivo derivative of SIVmac251 (SIVmac32H/L28) was investigated. In naïve, Mauritian-derived cynomolgus macaques (Macaca fascicularis), SIVmac32H/L28 replicated to high peak titres (>10(8) SIV RNA copies ml(-1)), persisted at high levels and induced distinctive pathology in lymphoid tissues. In cynomolgus macaques vaccinated with SIVmacC8, no evidence of detectable superinfection was observed in 3/8 vaccinates following challenge 3 or 20 weeks later with SIVmac32H/L28. Analyses after SIVmac32H/L28 challenge revealed a significant reduction in viral RNA (P<0.001) and DNA levels between 20 week vaccinates and challenge controls. Amongst 3 week vaccinates, less potent protection was observed. However, analysis of env from breakthrough virus indicated >99% sequence similarity with the vaccine virus. Highly sensitive PCR assays that distinguish vaccine and challenge virus stocks demonstrated restimulation of replication of the vaccine virus SIVmacC8 in the face of potent protection against a vigorous, homologous challenge virus. Vaccine-induced antiviral neutralizing antibodies and anti-Nef CD8+ cytotoxic T cell responses did not correlate with the outcome of the challenge. Defining the mechanism of vaccine protection will need to account for the effective control of a genetically closely related challenge virus whilst remaining unable to suppress replication of the pre-existing vaccine virus. The role of innate and intrinsic anti-retroviral immunity in the protection conferred by live attenuated SIV vaccines warrants careful study.Journal of General Virology 10/2008; 89(Pt 9):2240-51. · 3.36 Impact Factor