Women exposed to single-dose nevirapine in successive pregnancies: effectiveness and nonnucleoside reverse transcriptase inhibitor resistance.

OBJECTIVE: To assess the impact of prior exposure to single-dose nevirapine (sdNVP) on mother-to-child transmission and genotypic resistance in HIV-infected women. DESIGN: Prospective study of 120 women exposed to the HIVNET 012 sdNVP regimen in two successive pregnancies and 240 antiretroviral (ARV)-naïve, multiparous women who received sdNVP for the first time. RESULTS: One hundred and eight of 120 and 193 of 240 women returned for a postpartum visit by 6 weeks. HIV-1 was detected in 11.1% (95% confidence interval = 5.9-18.6) of the infants of women previously exposed to sdNVP and 4.2% (95% confidence interval = 1.3-7.0) of those exposed for the first time (P = 0.028). Rates of maternal HIV-1 genotypic resistance at 6 weeks postdelivery were 37.5% and 46.4%, respectively (P = 0.119). Sensitive mutation-specific real-time PCR testing found three of 12 previously exposed women who transmitted HIV-1 to their infants had either K103N or Y181C at baseline compared with one of eight ARV-naïve, transmitting women who had Y181C. None of 40 randomly selected nontransmitting women from either group had detectable NVP resistance mutations prior to sdNVP exposure. CONCLUSION: This study shows that effectiveness of sdNVP may be compromised by prior exposure to sdNVP, although the increase in transmission rate after prior exposure could not be explained by the detection of NVP resistance mutations prior to re-exposure as measured both by standard genotyping and highly sensitive allele-specific PCR assays. Furthermore, transmission rates of women with prior exposure were not higher than those reported elsewhere.

Selection and persistence of viral resistance in HIV-infected children after exposure to single-dose nevirapine.

BACKGROUND: Single-dose nevirapine (sd-NVP) is the mainstay of prevention of mother-to-child transmission programs in developing countries. Exposure to sd-NVP selects for resistance mutations, however. We longitudinally assessed these mutations in HIV-1-infected infants from Soweto and Durban, South Africa. METHODS: We prospectively followed 465 infants who received sd-NVP after enrolling their mothers when pregnant. If HIV infected, their virus was genotyped, using the ViroSeq HIV-1 Genotyping System, to detect resistant mutations. Those with resistance were genotyped at 6 months and then every 6 months out to 18 months if resistance was detected at the previous visit. RESULTS: Of 53 HIV-infected infants, 24 (45.3%) had detectable resistance at their first visit, when the most frequent mutations were Y181C (75%), K103N (25%), and Y188C (12%). Of those whose visit was before 12 weeks of age, 2 of 42 infants shared identical resistance mutations with their mothers. By 18 months of age, 11 of 24 infants with resistance had died and 1 still had the Y181C mutation. CONCLUSIONS: Resistant mutations were selected in half of the infants exposed to sd-NVP, but fewer were detected over time and, unlike the case in their mothers, Y181C dominated initially and persists. Transient resistance mutations may have a negative impact on highly active antiretroviral therapy in infants and children.

Transmission rates in consecutive pregnancies exposed to single-dose nevirapine in Soweto, South Africa and Abidjan, Côte d'Ivoire.

BACKGROUND: Large numbers of women receive single-dose nevirapine (sdNVP) to prevent mother-to-child transmission (MTCT) of HIV; over time, an increasing proportion will return to prevention of MTCT programs for a second pregnancy. Because sdNVP selects resistance in a high percentage of women, we compared the effectiveness of sdNVP in preventing peripartum MTCT in successive pregnancies. METHODS: Prospective cohorts were recruited from MTCT programs in South Africa and Côte d'Ivoire. HIV-1-infected women and their infants exposed to sdNVP in 2 consecutive pregnancies-used alone or with zidovudine (ZDV) or ZDV plus lamivudine-were included. RESULTS: The median age of women at their initial exposure to sdNVP in Soweto (n = 120) and Abidjan (n = 41) was 26 (interquartile range [IQR]: 22-29) years and 28 (IQR: 24-31) years, respectively, and their median delivery interval was 21 (IQR: 15-29) months and 26 (IQR: 20-32) months, respectively. Transmission rates in Soweto and in Abidjan were 11.1% and 13.2% for the first pregnancy and 11.1% and 5.4% for the second pregnancy (P = 1.000 and P = 0.449 for Soweto and Abidjan, respectively, in unpaired analysis). CONCLUSION: This analysis suggests that the effectiveness of sdNVP when used in successive pregnancies is probably not impaired, possibly because viral resistance selected by prior exposure to sdNVP may wane with time.