Antiretroviral resistance mutations among pregnant human immunodeficiency virus type 1-infected women and their newborns in the United States: Vertical transmission and clades

To assess the impact of antiretroviral resistance on perinatal transmission prevention efforts, human immunodeficiency virus type 1 (HIV-1) genotypic resistance testing was done for 220 HIV-1-infected, zidovudine (AZT)-expose d pregnant women and 24 of their infected infants. The women were prospecti vely enrolled in 4 US cities in 1991-1997. Phylogenetic and sequencing anal yses revealed 5 women with non-clade B infections traced to western African origins. AZT-associated mutations were detected in 17.3% of pregnant women , whereas genotypic resistance to nonnucleoside reverse-transcriptase inhib itors and protease inhibitors was infrequent. No significant association wa s detected between perinatal transmission and the presence of either AZT or nucleoside reverse-transcriptase inhibitor resistance-associated mutations . AZT resistance mutations were detected in 2 (8.3%) neonatal samples, but the mutation pattern was not identical to the mother's. Although no effect of viral resistance on mother-infant transmission was demonstrated, the adv ent of more-potent drug classes and the potential for the rapid emergence o f resistance warrant prospective surveillance.