Coreceptor usage of HIV-1 isolates representing different genetic subtypesobtained from pregnant Cameroonian women

In this study, coreceptor usage of HIV-1 other than subtype B in relation t o HIV-I transmission from mother to child was investigated. Repeated sampli ng of 42 HIV-l-seropositive, asymptomatic women in Cameroon during the seco nd and third trimesters of pregnancy, at delivery, and 6 months postpartum were performed. Env subtyping was carried out from uncultured peripheral bl ood mononuclear cells (PBMCs) by heteroduplex mobility assay and, whenever necessary, by DNA sequencing. Virus isolates were tested for coreceptor usa ge on human cell lines-U87.CD4 and GHOST(3)-engineered to express stably CD 4 and the chemokine receptors CCR1, CCR2b, CCR3, CCR5, or CXCR4, or the orp han receptors BOB/gpr15 or Bonzo/STRL33/TYMSTR Transmission rate was 11.9%. Viruses were predominantly envelope subtype A and used CCR5 as coreceptor and, surprisingly, 4 of 28 (14.2%) isolates from mothers and 1 of 3 isolate s from children used the orphan receptor Bonzo as well. In 2 transmitting m others from whom sequential HIV-1 isolates were available, viral coreceptor usage evolved from CCR5 monotropic to CCR5/Bonzo dual tropic during pregna ncy, and in 1 case transmission of this virus could be documented. Our data suggest that evolution of HIV-1 coreceptor usage to dual (or multi-) tropi sm may occur during pregnancy.