Search

Background The rapid expansion of antiretroviral treatment in resource-limited settings is raising concerns regarding the emergence and transmission of HIV drug resistance (HIVDR). We evaluated the extent of transmission of drug-resistant HIV strains in four Central African countries: the Republic of Congo, Central African Republic, Chad and Cameroon.Methods The World Health Organization (WHO) HIVDR threshold survey was implemented in major treatment areas in each country. Pregnant women who were aged <25 years, who were at first pregnancy and who were HIV type-1-positive were enrolled at each site in 2006–2007 for geno-typing. HIVDR prevalence was categorized using the WHO threshold survey binomial sequential sampling method.Results The prevalence of HIVDR in Brazzaville and Bangui sites could not be classified because the eligible sample number was not reached. HIVDR prevalence was low (<5%) in N'Djamena for all drug classes. In Yaoundé, we found one individual with the D67D/N mutation and two with K103N. HIVDR prevalence was categorized as low (<5%) for protease inhibitors (PIs) and nucleoside reverse transcriptase inhibitors (NRTIs), and moderate (=5-=15%) for non-NRTIs (NNRTIs). HIVDR prevalence in Douala was low for PIs and NNRTIs, and moderate for NRTIs as we identified one individual with M184V plus K101E plus G190A mutations and a second with D67D/N.Conclusions The moderate HIVDR prevalence found in Yaoundé and Douala indicate that efforts should be made in Cameroon to prevent HIVDR; however, additional surveys are needed to confirm this trend. This study highlighted challenges presented by the WHO methodology, such as additional costs, workload, difficulties in acquiring even small sample numbers and the necessity for better quality assurance of HIV testing and record keeping at antenatal clinics.

We analysed whether mutations associated with resistance to antiretroviral (ARV) drugs circulate among treatment-naive HIV-1-infected individuals at a period when these drugs started to become more widely available in Africa. Overall, major resistance mutations in the polgene, as defined by the International AIDS Society Resistance Testing-USA panel, were observed in 16 treatment-naive individuals. Eight of the 97 patients tested in Burkina Faso bore mutations conferring resistance to one drug class of ARV drugs: two to nucleoside reverse transcriptase inhibitors (NRTIs; M41L [n=1], M41L+T69S [n=1]), four to non-NRTIs (NNRTIs; V106A/V [n=1] and V108I [n=3]) and two to protease inhibitors (PIs; L33F [n=2]). In Cameroon, resistance mutations were identified in 8 of 102 patients: three to PIs (M46I/L [n=2], L33F [n=1]), three to NRTIs (T69N/T [n=1], M184V [n=1], A62V [n=1]) and two to NNRTIs (P236L [n=1], V108I [n=1]). It is important to note that not all geno-typic drug-resistance algorithms give similar interpretations to the observed mutations. Population surveillance for ARV drug resistance is required and should be included in all implementation programmes.

ABSTRACTThe tools currently available for genetic subtyping of human immunodeficiency virus type 1 are laborious or can be used only for the analysis of a limited number of samples and/or subtypes. We developed and evaluated a molecular biology-based method using subtype-specific oligonucleotide probes for envgenotyping of subtypes A through G, CRF01_AE, and CRF02_AG. DNA enzyme immunoassay (DEIA) genotyping is based on nested PCR amplification of the 5' end of the envgene (proviral DNA), followed by subtype-specific hybridization and immunoenzymatic detection on microplates. DEIA genotyping was validated with a large number of samples (n= 128) collected in Europe (France; n= 47), West-Central Africa (Cameroon; n= 36), and West Africa (Senegal; n= 45). Three different formats, depending on the distribution of subtypes in the three countries, were developed. The results were compared with those obtained by sequencing of the V3-V5 region and phylogenetic analysis or an envheteroduplex mobility assay. Additional sequencing and phylogenetic analyses of the DEIA region (the first codon of the env coding sequence to the middle of conserved region C1 of gp120) were performed to investigate the reasons for discrepancies. Intense and highly specific reactions between the oligonucleotide probes and the corresponding samples were observed. Overall, correct identification was achieved for 107 of 128 samples (83.6%). One sample was not amplified, 10 (8%) were nontypeable (NT), and 10 (8%) were misidentified. Six of the 10 discordant samples were further investigated by phylogenetic analysis, which indicated that these samples corresponded to recombinants involving the env 5' end and the V3 and V5 regions of the two parental clades. Sequencing of NT samples showed numerous differences between sample and probe sequences, resulting in a lack of hybridization, and revealed the limitations of the selected probes in terms of specificity and sensitivity. We demonstrated the feasibility of DEIA genotyping: six subtypes plus the two most prevalent circulating recombinant forms were discriminated by using the 5' end of the envgene. This method can be adapted to the local situation by including only probes that correspond to the prevalent strains.

ABSTRACTApoptosis of CD4+T lymphocytes, induced by contact between human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (gp120) and its receptors, could contribute to the cell depletion observed in HIV-infected individuals. CXCR4 appears to play an important role in gp120-induced cell death, but the mechanisms involved in this apoptotic process remain poorly understood. To get insight into the signal transduction pathways connecting CXCR4 to apoptosis following gp120 binding, we used different cell lines expressing wild-type CXCR4 and a truncated form of CD4 that binds gp120 but lacks the ability to transduce signals. The present study demonstrates that (i) the interaction of cell-associated gp120 with CXCR4-expressing target cells triggers a rapid dissipation of the mitochondrial transmembrane potential resulting in the cytosolic release of cytochrome cfrom the mitochondria to cytosol, concurrent with activation of caspase-9 and -3; (ii) this apoptotic process is independent of Fas signaling; and (iii) cooperation with a CD4 signal is not required. In addition, following coculture with cells expressing gp120, a Fas-independent apoptosis involving mitochondria and caspase activation is also observed in primary umbilical cord blood CD4+T lymphocytes expressing high levels of CXCR4. Thus, this gp120-mediated apoptotic pathway may contribute to CD4+T-cell depletion in AIDS.