ABSTRACT
BACKGROUND: In many preclinical AIDS research studies, antiretroviral therapy (ART) is administered to experimentally simian immunodeficiency (SIV)-infected rhesus macaques for reduction of viral load to undetectable levels. Prolonged treatment of macaques with a high dose of PMPA (9-[2-(r)-(phosphonomethoxy) propyl] adenine or tenofovir; 30 mg/kg of body weight subcutaneously once daily) can result in proximal renal tubular dysfunction, a Fanconi-like syndrome characterized by glucosuria, aminoaciduria, hypophosphatemia, and bone pathology. In contrast, chronic administration of a low dose of PMPA (10 mg/kg subcutaneously once daily) starting at birth does not seem to be associated with any adverse health effects within 3 years of treatment. In contrast to PMPA, limited information on systemic toxicity in rhesus monkeys is available for FTC (5-fluoro-1-(2R,5S)-[2-(hydroxymethyl)-1,3-oxathiolan-5-yl]cytosine; emtricitabine) and stavudine (d4T). RESULTS: In this study, the clinical and biochemical correlates of tubular nephrosis in SIV-infected rhesus macaques associated with systemic administration of high-dose ART consisting of the three nucleoside analog inhibitors PMPA, FTC, and d4T were investigated. It was found that acute renal failure was uncommon (7.1% of treated animals) and that morphologic evidence of nephropathy, which persisted for more than 300 days following discontinuation of the drug cocktail, was more frequent (52.4% of treated animals). While parameters from single time points lacked predictive value, biochemical alterations in Blood Urea Nitrogen (BUN) and phosphorus were frequently identified longitudinally in the blood of ART-treated animals that developed evidence of nephropathy, and these longitudinal changes correlated with disease severity. CONCLUSIONS: Recommendations are proposed to limit the impact of drug-induced renal disease in future SIV macaque studies.
ABSTRACT
The immunologic and virologic outcome of therapeutic DNA-vaccines administered during antiretroviral therapy (ART) using electroporation with or without (interleukin) IL-2 treatment was evaluated in the SIVmac239/macaque model. Rhesus macaques inoculated with pathogenic SIVmac239 were treated with ART [(R(-9-(2-phosphonomethoxypropyl) adenine) (PMPA), FTC, Zerit] from weeks 13 to 41 postinfection (wpi). Group 1 (n = 7) received ART only, groups 2 and 3 (each n = 6) additionally received SIVmac239-derived gp140Env, GagPol, and TatRevNef plasmids by in vivo electroporation at 22, 26, 30, and 34 wpi, and group 3 also IL-2 for 14 days after each vaccination. Endpoints evaluated were viral load, Gag(181189)-specific CD8+ T-cell responses in MamuA01+ animals, lymphoproliferative responses, and CD4 T-cell counts. Viremia in all animals dropped below 200 RNA copies/ml during ART. Frequencies of Gag(181189)-specific CD8+ T cells prior to ART were detectable in all three groups (1.27-3.01%) and increased significantly (p < 0.01) postvaccination with maximum responses after the fourth immunization (0.2% versus 3.49-7.15%). Gag(181189)-specific CD8+ T-cell frequencies increased post-ART cessation in all groups and remained at significantly higher levels (p < 0.001) until the end of the study (75 wpi) in both groups of vaccinated animals. Lymphoproliferative responses were detected against Gag in a limited number of animals after vaccination and post-ART. However, plasma RNA viral loads rebounded after ART termination to similar levels in all three groups, but remained below 10(5) copies/ml until the end of the study, which could be a late effect of the triple drug therapy.
