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Background: In this work, we investigated the genetic diversity of HIV-1 and the presence of mutations conferring antiretroviral drug resistance in 50 drug-naïve infected persons in the Republic of Congo (RoC). Samples were obtained before large-scale access to HAART in 2002 and 2004., Methods: To assess the HIV-1 genetic recombination, the sequencing of the pol gene encoding a protease and partial reverse transcriptase was performed and analyzed with updated references, including newly characterized CRFs. The assessment of drug resistance was conducted according to the WHO protocol., Results: Among the 50 samples analyzed for the pol gene, 50% were classified as intersubtype recombinants, charring complex structures inside the pol fragment. Five samples could not be classified (noted U). The most prevalent subtypes were G with 10 isolates and D with 11 isolates. One isolate of A, J, H, CRF05, CRF18 and CRF37 were also found. Two samples (4%) harboring the mutations M230L and Y181C associated with the TAMs M41L and T215Y, respectively, were found., Conclusion: This first study in the RoC, based on WHO classification, shows that the threshold of transmitted drug resistance before large-scale access to antiretroviral therapy is 4%.

In this study, we investigated the prevalence of human immunodeficiency virus type 1 (HIV-1) drug resistance mutations and genetic variability among Senegalese patients undergoing highly active antiretroviral therapy (ART) in the public health system. We conducted a cross-sectional study of 72 patients with suspected therapeutic failure. HIV-1 genotyping was performed with Viroseq HIV-1 Genotyping System v2.0 or the procedure developed by the ANRS AC11 resistance study group, and a phylogenetic analysis was performed. The median follow-up visit was at 40 (range, 12 to 123) months, and the median viral load was 4.67 (range, 3.13 to 6.94) log(10) copies/ml. The first-line therapeutic regimen was nucleoside reverse transcriptase inhibitors (NRTIs) plus efavirenz (EFV) or NRTIs plus nevirapine (NVP) (54/72 patients; 75%), and the second-line therapy was NRTIs plus a protease inhibitor (PI/r) (18/72; 25%). Fifty-five patients (55/72; 76.39%) had at least one drug resistance mutation. The drug resistance rates were 72.22 and 88.89% for the first-line and second-line ARTs, respectively. In NRTI mutations, thymidine analog mutations (TAMs) were found in 50.79% and the M184V mutation was found in 34.92% of the samples. For non-NRTI resistance, we noted a predominance of the K103N mutation (46.27%). For PI/r, several cases of mutations were found with a predominance of M46I and L76V/F at 24% each. The phylogenetic analysis revealed CRF02_AG as the predominant circulating recombinant form (43/72; 59.72%). We found a high prevalence of resistance mutations and a high rate of TAMs among Senegalese patients in the public health system. These findings emphasize the need to improve virological monitoring in resource-limited settings.

To evaluate the presence of drug resistance mutations in antiretroviral-naive patients in Dakar (Senegal), cross-sectional studies were conducted since the circulation of ARVs in the country. Protease and RT genes were sequenced in 96 baseline samples from patients included in the Senegalese Initiative for Antitretroviral Access treatment between 1998 and 2001 and for 104 samples from naive, recently diagnosed patients in 2003, 2005, and 2007. Phylogenetic analysis showed a predominance of CRF02_AG [128/200 (64%)] and a high genetic diversity with 10 other variants and 25 URFs. Analysis for the presence of drug resistance mutations according to the WHO SDRM 2009 list showed a prevalence of 4.16% for nucleoside inhibitors and 1.04% for protease inhibitors at the start of the structured Senegalese ART initiative and 1.9% for protease inhibitors at the time of scaling up. The prevalence in untreated patients remains low and stable, below 5% after 10 years of ARV circulation.

To document the actual genetic diversity of HIV-1 strains in the Republic of Congo, 114 HIV-1 positives persons were sampled in 2003 and 2004 after their informed consent. They were attending the teaching hospital, the reference health center in Makelekele, Brazzaville and the regional hospital centers in Pointe-Noire, Gamboma and Ouesso. A total of 104 samples were genetically characterized by direct sequencing of the p24 gag region and 80 were also subtyped in the V3-V5 env region. The genetic subtype distribution of the Congolese strains showed the predominance of subtype A (36.5% and 32.5% in gag and env, respectively) and G (30.8% and 21.25%), whereas subtype D strains represented 12.5% and 15%. Subtypes C, F, H, J, K and the CRFs-01, -02, -05 -06, and also the recently characterized CRF18 were seen at lower rates. Finally, 4.8% (gag) and 6.25% (env) of the strains could not be classified. Moreover, a high intra-subtype diversity was observed in our study. Among 70 strains which have been characterized in the two genomic regions, 14 (20%) appeared to be unique recombinants. These data show a high genetic variability in the Republic of Congo, where all the subtypes have been documented together with certain subsubtypes and several CRFs.

Most human immunodeficiency virus (HIV) drug susceptibility studies have involved subtype B strains. Little information on the impact of viral diversity on natural susceptibility to antiretroviral drugs has been reported. However, the prevalence of non-subtype-B (non-B) HIV type 1 (HIV-1) strains continues to increase in industrialized countries, and antiretroviral treatments have recently become available in certain developing countries where non-B subtypes predominate. We sequenced the protease and reverse transcriptase (RT) genes of 142 HIV-1 isolates from antiretroviral-naive patients: 4 belonged to group O and 138 belonged to group M (9 subtype A, 13 subtype B, 2 subtype C, 5 subtype D, 2 subtype F1, 9 subtype F2, 4 subtype G, 5 subtype J, 2 subtype K, 3 subtype CRF01-AE, 67 subtype CRF02-AG, and 17 unclassified isolates). No major mutations associated with resistance to nucleoside reverse transcriptase inhibitors (NRTIs) or protease inhibitors were detected. Major mutations linked to resistance to non-NRTI agents were detected in all group O isolates (A98G and Y181C) and in one subtype J virus (V108I). In contrast, many accessory mutations were found, especially in the protease gene. Only 5.6% of the 142 strains, all belonging to subtype B or D, had no mutations in the protease gene. Sixty percent had one mutation, 22.5% had two mutations, 9.8% had three mutations, and 2.1% (all group O strains) had four mutations. In order of decreasing frequency, the following mutations were identified in the protease gene: M36I (86.6%), L10I/V (26%), L63P (12.6%), K20M/R (11.2%), V77I (5.6%), A71V (2.8%), L33F (0.7%), and M46I (0.7%). R211K, an accessory mutation associated with NRTI resistance, was also observed in 43.6% of the samples. Phenotypic and clinical studies are now required to determine whether multidrug-resistant viruses emerge more rapidly during antiretroviral therapy when minor resistance-conferring mutations are present before treatment initiation.