Background: Environmentally driven immune activation was suggested to contribute to high rates of HIV-1 infection in Africa. We report here a study of immune activation markers and susceptibility to HIV-1 infection in vitro of forty-five highly exposed uninfected partners (EUs) of HIV-1 infected individuals in Central African Republic, in comparison with forty-four low-risk blood donors (UCs). Results: Analysis of T lymphocyte subsets and activation markers in whole blood showed that the absolute values and the percentage of HLA-DR⁺CD4 T cells and of CCR5⁺CD4 T cells were lower in the EUs than in the UCs (p = 0.0001). Mutations in the CCR5 coding region were not found in either group. Susceptibility to in vitro infection of unstimulated peripheral blood mononuclear cells, prior of PHA activation, was decreased in EUs compared to UCs, either using a CXCR4-tropic or a CCR5-tropic HIV-1 strain (p = 0.02 and p = 0.05, respectively). Levels of MIP-1β, but not of MIP-1α or RANTES, in the supernatants of PHA-activated PBMC, were higher in the EUs than in the UCs (p = 0.007). Conclusion: We found low levels of CD4 T cell activation and reduced PBMC susceptibility to HIV-1 infection in Central African EUs, indicating that both may contribute to the resistance to HIV-1 infection.

Non-B HIV-1 samples collected in France between 1999 and 2001 were sequenced in the env, reverse transcriptase (RT), and protease genes (1) to characterize further the non-B strains circulating in the country, (2) to assess the importance of recombination, and (3) to describe the polymorphism of RT and protease genes and appreciate a possible impact on susceptibility to antiretroviral (ARV) drugs. The results show that, within a background of CRF02_AG predominance, there is a high genetic diversity of non-B isolates, including intersubtype recombinants. There is an extensive polymorphism of protease and RT genes compared with B consensus sequences; we have so far no data indicating that these non-B isolates may have reduced sensitivity to ARV drugs.

Non-B HIV-1 viruses are predominant in developing countries where access to antiretroviral drugs (ARVs) is progressively being intensified. It is important to obtain more data on the susceptibility of these viruses to available ARVs. CRF01_AE, CRF02_AG, and subtype C strains of HIV-1 obtained from untreated patients from Vietnam, Cote d'Ivoire, and India were analyzed for their in vitro susceptibility to NRTIs, NNRTIs, PIs, and an entry inhibitor (T-20) using a recombinant viral assay (PHENOSCRIPT). The corresponding viruses, which had been previously sequenced in reverse transcriptase (RT), protease (prot), plus envelope (env) C2/V3 genes and had therefore been fully characterized, were further sequenced in env HR1 + HR2 regions. CRF01_AE isolates are sensitive to NRTIs and NNRTIs with the exception of one isolate that exhibits a decreased susceptibility to NNRTIs associated with a I135T substitution in RT. CRF02_AG and subtype C viruses are sensitive to NRTIs and NNRTIs but some CRF02_AG isolates tend to be resistant to abacavir, potentially related to associated substitutions of RT at positions 123 (D123N) plus 135 (I135V). Whereas all but one CRF01_AE isolates are fully susceptible to PIs, some CRF02_AG and, more frequently, some subtype C isolates are resistant to atazanavir. The role of substitutions in prot at positions of secondary resistance mutations 20, 36, 63, and 82 is raised with a potentially crucial role of the V82I substitution. Finally, all viruses tested, regardless of the CRF or subtype, are fully susceptible to T-20.

Background: Transmission of HIV-1 variants with resistance to reverse transcriptase (RT) and protease inhibitors has been widely characterized in developed countries. However, no clear evidence of primary resistance to HIV-1 fusion inhibitors has been shown so far. We wished to investigate the possibility of genotypic resistance to enfuvirtide (T20) in a cohort of antiretroviral-naive, recently infected patients. Methods: We included patients from the Aquitaine Cohort with an estimated date of seroconversion in 2004 and 2005, a plasma sample obtained less than 18 months after seroconversion and no prior history of antiretroviral therapy. RT, protease and gp41 sequences were determined by direct population sequencing from plasma samples and drug resistance mutations were reported. Results: A total of 55 patients were included in the study. The overall prevalence of transmitted HIV-1 resistance was 20%. Two patients had viruses with resistance mutations to T20. The first case had an N42D mutation in the HR1 region of the gp41, along with transmitted resistance mutations in the protease (D30N, M36I, N88D) and in the RT (M41L, L210W, T215D). The second case had a G36D HR1 mutation, with no evidence of other drug resistance mutations. Conclusion: We have shown the first cases of primary resistance to T20 in recently infected patients in southwestern France. Epidemiological surveillance of the transmission of drug-resistant HIV-1 should include the resistance to T20.

We have studied 65 HIV-1-infected untreated patients recruited in Caracas, Venezuela with TCD4 counts ≥350/μl. The reverse transcriptase and protease sequences of the virus were sequenced, aligned with reference HIV-1 group M strains, and analyzed for drug resistance mutations. Most of the viruses were subtype B genotype in both the protease and RT genomic regions. Five of the 62 virus isolates successfully amplified showed evidence of recombination between protease and RT, with their protease region being non-B while their RT region was derived from subtype B. Four strains were found bearing resistance mutations either to NRTIs, NNRTIs, or PIs. The prevalence of HIV-1 isolates bearing resistance mutations was therefore above the 5% threshold of WHO.