Vertical transmission of human immunodeficiency virus type 1 (HIV-1) results from the interplay of virologic, immunologic, and pharmacological factors. Thus, HIV-1 variants are under selection for their ability to grow to high levels within the mother and for their ability to initiate a new infection within the infant. The use of antiretroviral drugs during pregnancy adds another level of selection to this process, wherein the ability to efficiently grow in the presence of the drug may select for mutants with altered fitness for spreading to infants.
De Jose MI, Ramos JT, Alvarez S, Jimenez J, Muñoz-Fernández MA. Vertical Transmission of HIV-1 Variants Resistant to Reverse Transcriptase and Protease Inhibitors. Arch Intern Med. 2001;161(22):2738-2739. doi: