Emergence of antiretroviral resistance in HIV-positive women receiving combination antiretroviral therapy in pregnancy

Background: Antenatal anti retroviral therapy is integral to preventing vertical transmission of HIV-1. The impact of temporary triple antiretroviral therapy in pregnancy on the emergence of antiretroviral resistance has not been studied. Objective: To determine the impact of temporary triple antiretroviral therapy in pregnancy on emergence of antiretroviral resistance. Methods: Pregnant HIV-1 infected women with a pre-treatment CD4 cell count >300 x 10(6)/l initiated triple antiretroviral therapy in the third trimester and discontinued postpartum. Genotypic resistance testing was performed after antiretroviral cessation and on pretreatment samples when postpartum samples showed primary mutations. Results: In a cohort of 50 women who initiated antiretroviral therapy in pregnancy, 39 (78%) had postpartum HIV-1 nucleotide sequences available for analysis: 35 of these (90%) were previously antiretroviral naive. Seven primary mutations, V106A (one), Y181C (two), G190A (one), K101E (one), M184V (one), T215S (one) were detected in five (13%) women. All five were on regimens that included nevirapine and all were antiretroviral therapy naive prior to the index pregnancy. Four had no mutations detected pretreatment (one did not have a pretreatment analysis available, viral load 83 copies/ml). The median duration of antiretroviral exposure was 70 days. Conclusion: Emergence of genotypic resistance is significant in this cohort of pregnant women. All mutations detected were in those that took nevirapine-containing regimens. The clinical implications of these mutations are unknown. (C) 2005 Lippincott Williams Wilkins.