BackgroundThe impact of extended use of ART in developing countries has been enormous. A thorough understanding of all factors contributing to the success of antiretroviral therapy is required. The current study aims to investigate the value of cross-sectional drug resistance monitoring using DNA and RNA oligonucleotide ligation assays (OLA) in treatment cohorts in low-resource settings. The study was conducted in the first cohort of children gaining access to structured ART in Peru.MethodsBetween 2002–5, 46 eligible children started the standard regimen of AZT, 3TC and NFV Patients had a median age of 5.6 years (range: 0.7-14y), a median viral load of 1.7·105 RNA/ml (range: 2.1·103 – 1.2·106), and a median CD4-count of 232 cells/μL (range: 1–1591). Of these, 20 patients were classified as CDC clinical category C and 31/46 as CDC immune category 3. At the time of cross-sectional analysis in 2005, adherence questionnaires were administered. DNA OLAs and RNA OLAs were performed from frozen PBMC and plasma, RNA genotyping from dried blood spots.ResultsDuring the first year of ART, 44% of children experienced virologic failure, with an additional 9% failing by the end of the second year. Virologic failure was significantly associated with the number of resistance mutations detected by DNA-OLA (p < 0.001) during cross-sectional analysis, but also with low immunologic CDC-scores at baseline (p < 0.001). Children who had been exposed to unsupervised short-term antiretrovirals before starting structured ART showed significantly higher numbers of resistance mutations by DNA-OLA (p = 0.01). Detection of M184V (3TC resistance) by RNA-OLA and DNA-OLA demonstrated a sensitivity of 0.93 and 0.86 and specificity of 0.67 and 0.7, respectively, for the identification of virologic failure. The RT mutations N88D and L90M (NFV resistance) detected by DNA-OLA correlated with virologic failure, whereas mutations at RT position 215 (AZT resistance) were not associated with virologic failure.ConclusionsAdvanced immunosuppression at baseline and previous exposures to unsupervised brief cycles of ART significantly impaired treatment outcomes at a time when structured ART was finally introduced in his cohort. Brief maternal exposures to with AZT +/− NVP for the prevention of mother-to-child transmission did not affect treatment outcomes in this group of children. DNA-OLA from frozen PBMC provided a highly specific tool to detect archived drug resistance. RNA consensus genotyping from dried blood spots and RNA-OLA from plasma consistently detected drug resistance mutations, but merely in association with virologic failure.

Certain chemokine receptors serve as cofactors for HIV type 1 envelope (env)-mediated cell-cell fusion and virus infection of CD4-positive cells. Macrophage tropic (M-tropic) HIV-1 isolates use CCR5, and T cell tropic (Ttropic) strains use CXCR4. To investigate the cofactors used by simian immunodeficiency viruses (SIV), we tested four T-tropic and two M-tropic SIV env proteins for their ability to mediate cell-cell fusion with cells expressing CD4 and either human or nonhuman primate chemokine receptors. Unlike HIV-1, both M-and T-tropic SIV envs used CCR5 but not CXCR4 or the other chemokine receptors tested. However, by testing a panel of CCR5͞CCR2b chimeras, we found that the structural requirements for CCR5 utilization by M-tropic and T-tropic SIV strains were different. T-tropic SIV strains required the second extracellular loop of CCR5 whereas a closely related M-tropic SIV strain could, like M-tropic HIV-1 strains, use the amino-terminal domain of CCR5. As few as two amino acid changes in the SIV env V3 domain affected the regions of CCR5 that were critical for fusogenic activity. Receptor signaling was not required for either fusion or infection. Our results suggest that viral tropism may be inf luenced not only by the coreceptors used by a given virus strain but also by how a given coreceptor is used.

Background: Vaginal HIV-1 shedding has been associated with Trichomonas vaginalis (TV) infection and could play a role in HIV transmission. The purpose of the study was to examine if effective TV treatment reduces the presence of vaginal HIV-1 RNA. Methods: TV+ women attending an HIV outpatient clinic in New Orleans, LA, who resolved infection (n = 58) and TV-negative controls (n = 92), matched on antiretroviral therapy (ART) were examined and interviewed at baseline, 1, and 3 months. TV status was tested by culture and the amount of cell free HIV-1 RNA in the vaginal fluids was determined by the Amplicor HIV-1 Monitor ultrasensitive assay. Results: Most women (81.3%) were black and the mean age was 37.5 (SD 8.7). At baseline, 46.0% had plasma HIV-1 RNA ≥10,000 copies/mL, 26.4% had CD4<200 cells/μL, 54.7% were taking ART, and only 26.0% had detectable HIV-1 RNA in their vaginal fluids. TV-positive women who were effectively treated for TV were less likely to shed HIV vaginally at 3-months post-treatment compared to baseline (R.R. 0.34, 95% CI: 0.12–0.92, P = 0.03), whereas there was no change for TV-negative women. Conclusion: This study provides additional support that reducing TV infection among HIV-positive women may have an impact on the prevention of HIV transmission. Reasons for the delayed treatment effect and the effect on cervical shedding need further investigation.