Search

Limited information is available on the prevalence among rural Africans of host genetic polymorphisms conferring resistance to HIV-1 infection or slowing HIV disease progression. We report the allelic frequencies of the AIDS-related polymorphisms CCR2-64I, SDF1-3'A, and CCR5-Delta32 in 321 volunteers from 7 ethnic groups in Cameroon. Allelic frequencies differed among the 7 ethnic groups, ranging from 10.8% to 31.3% for CCR2-64I and 0.0% to 7.1% for SDF1-3'A. No CCR5-Delta32 alleles were found. HIV seroprevalence was 6.9% in the total population and peaked at younger ages in girls and women than in boys and men. Among 15- to 54-year-olds, HIV seroprevalence varied from 2.0% to 11.1% among the village populations. Conditional logistic regression analysis using data from boys and men aged 15 to 54 years showed the number of CCR2-64I alleles to be a significant risk factor for HIV seropositivity (odds ratio per allele adjusted for age and matched on ethnic group = 6.3, 95% confidence interval: 1.3-30.3); this association was not found in women. The findings are consistent with the hypothesis that CCR2-64I alleles may delay HIV disease progression without affecting susceptibility to infection among men. We did not observe this relation among women, and other factors, such as multiple pregnancies or maternal stressors (eg, breastfeeding), may have masked any protective effect of CCR2-64I alleles. Further study of this issue among women is warranted. SDF1-3'A did not differ between HIV-seropositive and HIV-seronegative individuals but was associated with increasing age among HIV-seronegative women, suggesting a protective effect against HIV-1 infection.

Recently T-20 or enfuvirtide, the first drug of a new class of antiretrovirals targeting the entry stage of the virus life cycle, has been clinically approved. Enfuvirtide is a peptide derived from the HR2 region of the transmembrane glycoprotein from the HXB2 HIV-1 subtype B prototype strain that binds to the HR1 region. Drug resistance seems to occur in the HR1 region between amino acids 36 and 45. We examined to what extent this region is conserved in 184 non-B strains from Cameroon: 132 (71.7%) CRF02-AG, 14 (7.6%) subtype A, 11 (5.9%) F2, 9 (4.8%) subtype D, 8 (4.3%) subtype G, 4 (2.1%) CRF01-AE, 4 (2.1%) CRF11-cpx, and 2 (1.1%) CRF06-cpx. Among the 184 strains studied, no amino acid mutation was found in the highly conserved three amino acid motif at codons 36-38 (GIV) that are important determinants of viral susceptibility to enfuvirtide. Other common substitutions like Q40H and N42T were also absent. The N42S polymorphism was present in 148 (80.4%) strains. Analysis of the HR2 domain, from which the peptide is derived, indicated a much greater genetic variability as compared to HR1.

The performance of 4 rapid and simple assays: Camstix-HIV 1+2 (Camdiagnostix, Yaounde, Cameroon); Determine HIV 1+2+0 (Abbott Laboratories, Tokyo, Japan); Genie II HIV-1/HIV-2 (Bio-Rad, Marnes la Coquette, France); ImmunoComb II HIV 1 & 2 BiSpot (Orgenics, Yavne, Israel); and 2 fourth-generation ELISAs: Enzygnost HIV Integral (Dade Behring, Marburg, Germany) and Genscreen plus HIV Ag-Ab (Bio-Rad, Marnes la Coquette, France) currently used in Cameroon to detect HIV infections were evaluated on a local serum panel. A total of 503 samples were collected, using the Camstix-HIV 1+2 assay. Overall, 280 samples were confirmed HIV positive, 181 were negative, and 42 were indeterminate. All positive samples belonged to group M: CRF02_AG (73.5%), A1 (7.1%), A2 (1.2%), G (4.7%), F2 (5.1%), D (1.6%), CRF11 (1.6%), CRF06 (1.2%), and CRF01_AE (1.6%). Sensitivity, specificity, test efficiency, and positive and negative predictive values were calculated both including and excluding indeterminate samples. Except for Genie II and ImmunoComb II (98.9 and 99.3%, respectively), sensitivities were 100% for the remaining 4 tests. Specificities, efficiencies, and positive predictive values of all assays were negatively affected by the addition of HIV-indeterminate samples in the calculations. These data show the importance of prior test evaluations on local serum panels and in field conditions before a national policy for HIV screening is decided on and stress also the need to use tests and algorithms that can reduce the high number of HIV-indeterminate results in Africa.

HIV-1 in Cameroon is genetically diverse, but is predominated by the circulating recombinant form (CRF) 02_AG, which cocirculates among an array of other CRFs, unique recombinant forms (URFs), and all group M subtypes. In particular, our studies of HIV-1 diversity in the East Province found a high proportion of URFs and second generation recombinants (SGRs), suggesting this region of Cameroon may be a breading ground for new CRFs. Herein we present the full-length sequence analysis of one such CRF, composed primarily (66%) of unique, distant lineages of subtypes A and G in alternating regions throughout the genome. This CRF also combines segments in pol and env genes possessing intrasubtype distance (

To describe the presence of protease inhibitor (PI) resistance-associated mutations and subtype distribution in drug-naive villagers of six provinces of Cameroon, we sequenced the protease (PR) gene (297 bp) of 128 viruses. Secondary PI resistance-associated mutations were identified at five sites: L10I/V (16%), K20R (8%), M36I (98%), L63P (13%), and V77I (6%). No primary mutation in the PR was identified. Of the 128 specimens analyzed, subtypes A (11%), C(2%), D (6%), F2 (3%), G (6%), H (0.8%), J (6%), and CRF02_AG (60%) were identified. The mutations identified were not characteristic to any particular subtype. The absence of primary mutations, in addition to the few secondary mutations, gives good perspectives for PI treatment interventions in these rural areas.

To understand the evolution of HIV-1, the genetic and biological characteristics of viruses that infect persons living in regions in which the virus has been evolving for several decades must be studied. Thus, we investigated teh genetic subtypes, coreceptor usage, and syncytium-inducing ability of viruses in 47 HIV-1-infected blood samples from individuals living in rural villages in the equatorial rain forest and grass field regions in Cameroon. Heteroduplex mobility analysis (HMA) of gag (part of p24 and p7) and env (C2V5) or sequence and phylogenetic analysis of gag (part of p24 and p7), pol (protease), and env (C2V5), revealed a broad HIV-1 group M genetic diversity. Subtype analysis revealed genetic evidence of seven subtypes (A, C, D, F, G, H, and J) and three circulating recombinant froms (CRFs) (CRF01_AE, CRF02_AG, and CRF11_cpx). Only 15 (32%) of the 47 samples analyzed revealed a concordant subtype in all three genes (gag, pol, and env), while discordant subtypes and CRFs were identified for the remaining 32 (68%) samples. Two patterns of HIV-1 diversity could be discerned in two provinces. While more concordant subtypes in gag, pol, and env genes were identified in villages of South province (10 of 13, 77%), the HIV-1 diversity in the West province was characterized by intersubtype recombinants (63%). Five new intersubtype recombinants were identified including Agag Jpol Genv, Ggag Upol Aenv, AGgag Jpol Aenv, Agag AGpol Henv, and Cgag AGpol AGenv. All of the 40 viruses tested used the R5 coreceptor, of which four also used the X4 coreceptor. Four viruses were able to induce syncytia in MT-2 cells, however, syncytium induction did not correlate with coreceptor usage. This study further reveals the complexity of HIV-1 infection in rural Cameron and points to the future of the global epidemic, which may be characterized by more genetically diverse viruses.