Mother-to-child transmission in the United States of subtypes D and A/G human immunodeficiency virus type 1.

In the United States and Western Europe, most human immunodeficiency virus type 1 (HIV-1) infections are caused by subtype B. We analyzed the nucleotide sequence of HIV-1 RNA in plasma samples from 141 children enrolled into PACTG 377, a comparative study of several antiretroviral therapy regimens. Phylogenetic analysis revealed that two children, both born in the United States, were infected with non-B subtypes that are most commonly found in Africa: one with subtype D and the other with circulating recombinant form CRF02, an A/G recombinant lineage. Viral load assays performed to monitor treatment response underestimated the levels of HIV-1 RNA in the child with the A/G recombinant. These cases demonstrate mother-to-child transmission of non-B subtypes of HIV-1 in the United States. Non-B subtypes should be considered in the management of HIV-1-infected pregnant women and children to optimize strategies to prevent and treat pediatric HIV-1 infection.