Emergence and persistence of minor drug-resistant HIV-1 variants in Ugandan women after nevirapine single-dose prophylaxis.

BACKGROUND: Nevirapine (NVP) single-dose is still a widely used antiretroviral prophylaxis for the prevention of vertical HIV-1 transmission in resource-limited settings. However, the main disadvantage of the Non-nucleoside Reverse Transcriptase Inhibitor (NNRTI) NVP is the rapid selection of NVP-resistant virus with negative implications for subsequent NNRTI-based long-term antiretroviral therapy (ART). Here, we analysed the emergence of drug-resistant HIV-1 including minor variants in the early phase after NVP single-dose prophylaxis and the persistence of drug-resistant virus over time. METHODS AND FINDINGS: NVP-resistant HIV-1 harbouring the K103N and/or Y181C resistance mutations in the HIV-1 reverse transcriptase gene was measured from 1 week up to 18 months after NVP single-dose prophylaxis in 29 Ugandan women using allele-specific PCR assays capable of detecting drug-resistant variants representing less than 1% of the whole viral population. In total, drug-resistant HIV-1 was identified in 18/29 (62%) women; rates increased from 18% to 38% and 44% at week 1, 2, 6, respectively, and decreased to 18%, 25%, 13% and 4% at month 3, 6, 12 and 18, respectively. The proportion of NVP-resistant virus of the total viral population was significantly higher in women infected with subtype D (median 40.5%) as compared to subtype A (median 1.3%; p = 0.032, Mann-Whitney U test). 33% of resistant virus was not detectable at week 2 but was for the first time measurable 6-12 weeks after NVP single-dose prophylaxis. Three (10%) women harboured resistant virus in proportions >10% still at month 6. CONCLUSIONS: Current WHO guidelines recommend an additional postnatal intake of AZT and 3TC for one week to avoid NVP resistance formation. Our findings indicate that a 1-week medication might be too short to impede the emergence of NVP resistance in a substantial proportion of women. Furthermore, subsequent NNRTI-based ART should not be started earlier than 12 months after NVP single-dose prophylaxis.

Minor drug-resistant HIV type-1 variants in breast milk and plasma of HIV type-1-infected Ugandan women after nevirapine single-dose prophylaxis.

BACKGROUND: Nevirapine single-dose (NVP-SD) reduces mother-to-child transmission of HIV type-1 (HIV-1), but frequently induces resistance mutations in the HIV-1 genome. Little is known about drug-resistant HIV-1 variants in the breast milk of women who have taken NVP-SD. METHODS: Blood and breast milk samples of 39 HIV-1-infected Ugandan women were taken 6-12 weeks after NVP-SD intake. Samples were analysed by population sequencing and allele-specific real-time PCR (AS-PCR) with detection limits for NVP-resistant HIV-1 variants (K103N and Y181C) of < 1% of the total viral population. RESULTS: AS-PCR results for both plasma and breast milk were obtained for 19 women who constituted the final study group (HIV-1 subtype frequencies were A1 n = 11, D n = 5, G n = 2 and C n = 1). A total of 7 (37%) and 10 (53%) women carried NVP-resistant virus in breast milk and plasma, respectively. Overall, 71% (5/7) women with NVP-resistant HIV-1 in breast milk displayed >1 drug-resistant variant. Resistance in breast milk was higher at week 6 (6/13 samples [46%]) compared with week 12 (1/6 samples [17%]). In total, 10 drug-resistant populations harbouring the K103N and/or Y181C mutation were detected in the 19 breast milk samples; 7 (70%) were caused by resistant minorities (< 5% of the total HIV-1 population). In the four women with drug-resistant virus in both plasma and breast milk, the mutation patterns differed between the two compartments. CONCLUSIONS: Minor populations of drug-resistant HIV-1 were frequently found in breast milk of Ugandan women after exposure to NVP-SD. Further studies need to explore the role of minor drug-resistant variants in the postnatal transmission of (resistant) HIV-1.

Detection and quantification of minor human immunodeficiency virus type 1 variants harboring K103N and Y181C resistance mutations in subtype A and D isolates by allele-specific real-time PCR.

Nevirapine (single dose), commonly used to prevent the mother-to-child transmission of human immunodeficiency virus (HIV) in developing countries, frequently induces viral resistance. Even mutations which occur only in a minor population of the HIV quasispecies (<20%) are associated with subsequent treatment failure but cannot be detected by population-based sequencing. We developed sensitive allele-specific real-time PCR (ASPCR) assays for two key resistance mutations of nevirapine. The assays were specifically designed to analyze HIV-1 subtype A and D isolates accounting for the majority of HIV infections in Uganda. Assays were evaluated using DNA standards and clinical samples of Ugandan women having preventively taken single-dose nevirapine. Lower detection limits of drug-resistant HIV type 1 (HIV-1) variants carrying reverse transcriptase mutations were 0.019% (K103N [AAC]), 0.013% (K103N [AAT]), and 0.29% (Y181C [TGT]), respectively. Accuracy and precision were high, with coefficients of variation (the standard ratio divided by the mean) of 0.02 to 0.15 for intra-assay variability and those of 0.07 to 0.15 (K103N) and 0.28 to 0.52 (Y181C) for inter-assay variability. ASPCR assays enabled the additional identification of 12 (20%) minor drug-resistant HIV variants in the 20 clinical Ugandan samples (3 mutation analyses per patient; 60 analyses in total) which were not detectable by population-based sequencing. The individual patient cutoff derived from the clinical baseline sample was more appropriate than the standard-based cutoff from cloned DNA. The latter is a suitable alternative since the presence/absence of drug-resistant HIV-1 strains was concordantly identified in 92% (55/60) of the analyses. These assays are useful to monitor the emergence and persistence of drug-resistant HIV-1 variants in subjects infected with HIV-1 subtypes A and D.

Persistence of nevirapine in breast milk and plasma of mothers and their children after single-dose administration.

OBJECTIVES: Nevirapine is widely used in the developing world for the prevention of mother-to-child transmission (PMTCT) of HIV. A single mutation in the HIV genome is sufficient to lead to significant nevirapine resistance. Persistence of low-level drug concentrations in body compartments can foster resistance formation. In this study, concentration-time courses of nevirapine after single-dose administration were analysed over an extended post-partum period. PATIENTS AND METHODS: Breast milk and plasma samples of 62 HIV-positive Ugandan mother-child pairs who had received single-dose nevirapine were collected at delivery and 1, 2 and 6 weeks post-partum. Nevirapine concentrations were quantified by LC/tandem-mass-spectrometry using a quantification limit of 15 ng/mL, and a population pharmacokinetic (PK) analysis was performed. RESULTS: Concentration-time profiles in breast milk, maternal plasma and child plasma showed similar shapes. At week 1, median nevirapine concentrations were 164 ng/mL in maternal plasma, 114 ng/mL in breast milk and 183 ng/mL in child plasma. The population PK model predicted nevirapine concentrations>10 ng/mL (IC50 for nevirapine) for 13 days in breast milk, 14 days in maternal plasma and 18 days in child plasma in 80% of the samples. CONCLUSIONS: Nevirapine concentrations were present for 2-3 weeks in the three compartments. The concentrations are probably sufficiently high to protect most breastfed children from HIV transmission during the first 2 weeks. The long presence of slowly decreasing levels of nevirapine is likely to induce resistance formation. Post-natal addition of antiretrovirals for 1 week only, as recommended in the current PMTCT guidelines, will not suffice to avoid nevirapine resistance formation.

Intrapartum transmission after mucosal exposure to HIV was not observed with single-dose nevirapine for mother and child.

BACKGROUND: Intrapartum transmission of HIV has been reported to be associated with HIV in oropharyngeal secretions (OPSs) of the child. In this study, we analyze the frequency of intrapartum transmission after mucosal exposure to HIV after administration of single-dose nevirapine. METHODS: Eighty mothers and their children participating in a prevention of mother-to-child transmission of HIV program in Uganda who took a single dose of nevirapine according to the HIVNET012 protocol participated in the study. HIV-1 was quantified by polymerase chain reaction (PCR) in the mothers' and children's plasma, in cervicovaginal secretions (CVSs), and in the children's OPSs. Intrapartum transmission was defined as a positive HIV-1 RNA PCR result at week 1 or 2 after birth and a previously negative PCR result. RESULTS: Ninety-seven percent of children had detectable nevirapine in their OPS (median = 592 ng/mL). Fifty-seven (81%) children had HIV-negative OPSs, and 13 (19%) had HIV-positive OPSs. All children of mothers with HIV-negative CVSs had HIV-negative OPSs. HIV-1 levels of OPSs and CVSs correlated (r = 0.33, P = 0.027). None of the babies with detectable HIV-1 in the OPSs became infected by means of intrapartum transmission. CONCLUSION: Intrapartum HIV infection was not observed after mucosal exposure to HIV-1 after administration of a single dose of nevirapine to the mother and child.

Outcome of different nevirapine administration strategies in preventing mother-to-child transmission (PMTCT) programs in Tanzania and Uganda.

OBJECTIVE: Prevention-of-mother-to-child transmission (PMTCT) interventions based on single-dose nevirapine (NVP) are widely implemented in Africa, but strategies differ regarding how and when to administer the drug to women and infants. The aim of this study was to analyze the outcome of different strategies with regard to NVP intake in pregnant women and their infants in Tanzania and Uganda. METHODS: In an observational study carried out between March 2002 and December 2004, we compared a directly observed NVP administration strategy in Tanzania (supervised NVP intake for women and infants at a health unit) and a semi-observed administration strategy (self-administered NVP for women at home and supervised intake for infants at a health unit) in Uganda. RESULTS: The proportions of HIV-positive women accepting receipt of NVP from the health units were similar in the 2 countries (42.4% in Tanzania vs 45.6% in Uganda; P = .06). NVP intake in infants was significantly higher in Tanzania than in Uganda (43.7% vs 24.1%; P > .001). In a multivariate analysis, maternal age above 25 years, secondary education, Catholic faith, and having undergone PMTCT counseling at a hospital were independently associated with infant NVP intake. CONCLUSION: In our settings, the directly observed administration strategy resulted in a higher NVP intake in infants. The semi-observed strategy, which implies that, after home delivery, the infant has to be presented to a health unit for NVP administration, was less successful.

Outcome of Different Nevirapine Administration Strategies in Preventin g Mother-to-Child Transmission (PMTCT) Programs in Tanzania and Uganda.

OBJECTIVE: Prevention-of-mother-to-child transmission (PMTCT) interventions based on single-dose nevirapine (NVP) are widely implemented in Africa, but strategies differ regarding how and when to administer the drug to women and infants. The aim of this study was to analyze the outcome of different strategies with regard to NVP intake in pregnant women and their infants in Tanzania and Uganda. METHODS: In an observational study carried out between March 2002 and December 2004, we compared a directly observed NVP administration strategy in Tanzania (supervised NVP intake for women and infants at a health unit) and a semi-observed administration strategy (self-administered NVP for women at home and supervised intake for infants at a health unit) in Uganda. RESULTS: The proportions of HIV-positive women accepting receipt of NVP from the health units were similar in the 2 countries (42.4% in Tanzania vs 45.6% in Uganda; P = .06). NVP intake in infants was significantly higher in Tanzania than in Uganda (43.7% vs 24.1%; P < .001). In a multivariate analysis, maternal age above 25 years, secondary education, Catholic faith, and having undergone PMTCT counseling at a hospital were independently associated with infant NVP intake. CONCLUSION: In our settings, the directly observed administration strategy resulted in a higher NVP intake in infants. The semi-observed strategy, which implies that, after home delivery, the infant has to be presented to a health unit for NVP administration, was less successful.