Distinct patterns of emergence and fading of K103N and Y181C in women with subtype A vs. D after single-dose nevirapine: HIVNET 012

BACKGROUND: The HIVNET 012 trial in Uganda demonstrated that single-dose nevirapine (NVP) can prevent HIV-1 mother-to-child transmission. NVP resistance (NVPR) mutations were detected in 25% of women 6 to 8 weeks after NVP, with a higher rate of NVPR in women with subtype D than A. This study examined emergence and fading of specific NVPR mutations in women with these subtypes. METHODS: Plasma HIV-1 was analyzed with the ViroSeq genotyping system (Celera Diagnostics, Alameda, CA). Genotypes were obtained from paired samples collected 7 days and 6 to 8 weeks after NVP from 140 women, 83 with subtype A and 57 with subtype D. RESULTS: The rate of NVPR was similar in women with subtype A vs. D at 7 days but was higher in subtype D than A at 6 to 8 weeks. The higher rate of NVPR in subtype D was explained by at least 2 factors: Y181C faded from detection at a greater rate in women with subtype A (odds ratio = 3.06; 95% CI, 1.04, 8.90) and K103N accumulated at a greater rate in women with subtype D (odds ratio = 1.74; 95% CI, 0.62, 4.87). CONCLUSIONS: HIV-1 subtype influences selection and fading of HIV-1 variants with specific drug resistance mutations after antiretroviral drug exposure.     

Characterization of nevirapine resistance mutations in women with subtype A vs. D HIV-1 6-8 weeks after single-dose nevirapine (HIVNET 012)

OBJECTIVE: To compare the number and type of nevirapine (NVP) resistance mutations detected in Ugandan women with subtype A vs. D HIV-1 infection after single-dose NVP prophylaxis. DESIGN: In the HIVNET 012 trial, a higher rate of NVP resistance (NVPR) was seen in women with subtype D than A after single-dose NVP. In this study, the number and type of NVPR mutations detected 6-8 weeks after NVP were compared in women with subtypes A vs. D. METHODS: Plasma samples were available for 282 (92%) of 306 women who received NVP in HIVNET 012. Samples were analyzed with the ViroSeq HIV-1 Genotyping System (Applied Biosystems, Foster City, CA). Subtyping was performed by phylogenetic analysis of pol region sequences. RESULTS: Results were obtained for 279 women, including 147 with subtype A, 98 with subtype D, 6 with subtype C, and 28 with recombinant HIV-1. NVPR mutations were detected in 70 (25%) of 279 women. NVPR was more common in women with subtype D vs. A (35.7 vs. 19%, P = 0.0035). Complex patterns of NVPR mutations were detected in both subtypes. Among women with NVPR, 43% of women with subtype A and 46% of women with subtype D had >/=2 NVPR mutations. The mean number and pattern of NVPR mutations detected in women with subtypes A and D were similar. CONCLUSIONS: This study confirms a higher rate of NVPR in women with subtype D than A and further defines the pattern of NVPR mutations that emerge 6-8 weeks after single-dose NVP prophylaxis in these subtypes.     

Comparison of mother-to-child transmission rates in Ugandan women with subtype A versus D HIV-1 who received single-dose nevirapine prophylaxis: HIV Network For Prevention Trials 012

OBJECTIVE: To compare the rate of mother-to-child transmission (MTCT) in women with subtype A versus D HIV-1 who received single-dose nevirapine (NVP). METHODS: The MTCT rates were compared in women with subtype A versus D at birth and at 8 weeks and 18 months of age of the infants. The rate of late MTCT (after 8 weeks of age) was also analyzed. RESULTS: HIV-1 subtypes were determined for 300 of 306 women who received NVP in the HIV Network for Prevention Trials 012 study (158 women with subtype A and 105 women with subtype D). Infant infection status was known for 297 women. The cumulative rate of MTCT at 18 months was 13.2% for subtype A and 18.3% for subtype D (P=0.34). The rate of late transmission was 3.8% for subtype A and 7.6% for subtype D (P=0.28). Maternal baseline viral load was a significant predictor of MTCT, but maternal baseline CD4 cell count and subtype were not. CONCLUSIONS: No significant difference was observed in the rate of MTCT in women with subtype A versus D. There was a trend toward a higher rate of MTCT among women with subtype D, however, which was also apparent among women whose infants were infected after 8 weeks of age.     

体外无药物选择压力条件下HIV-1耐药基因突变的演变

目的 分离培养体外稳定传代的原代HIV-1耐药毒株,观察失去药物压力下,耐药毒株的体外生长以及主要耐药突变的演化趋势.方法 采集15例服用拉米夫定+司他夫定+萘韦拉平(3TC+D4T+NVP)的HIV-1感染者的外周血单个核细胞(PBMC),用体外共培养的方法从中分离原代HIV-1毒株;RT-PCR扩增耐药毒株历代培养上清的HIV-1 pol区基因并测序,在Stanford HIV Drug Resistance Database数据库进行耐药性分析.结果 15例患者中病毒载量>1000拷贝/ml的有8例,均成功分离出稳定传代的原代毒株,其中2株为耐药毒株,所携带的主要耐药突变分别是K103N/K238T和M184V/K103N/Y181C/H221Y,分别对NVP和3TC/NVP高度耐药;无药物压力的体外培养过程中,M184V、K103N、Y181C和H221Y等耐药突变可以稳定传代,但是K238T发生了回复突变.结论 分离出2株稳定传代的HIV-1耐药毒株,无药物压力情况下,携带K103N突变的毒株具有较好的复制适应性,可稳定传代;携带M184V和K103N/Y181C/H221Y的毒株也能够稳定复制;本研究中发现K238T耐药突变在失去药物的条件下稳定性差,提示该位点易发生回复突变.     

Two common mutations (D9N, N291S) in lipoprotein lipase: a cumulative analysis of their influence on plasma lipids and lipoproteins in men and women

We assessed the effect of two common mutations in the lipoprotein lipase gene (LPL), D9N and N291S, which have been shown to modulate plasma lipids in a wide spectrum of patients. A total of 1114 men and 1 144 women from the Framingham Offspring Study (FOS) were analyzed for these two LPL variants. Subsequently, the association with fasting plasma lipids and risk of coronary artery disease (CHD) was determined. We extended our study by calculating weighed means of lipids and lipoproteins in carriers and non-carriers for these LPL mutations in patients with genetic dyslipidemias, CHD patients and healthy controls. In the FOS sample, the D9N and N291S alleles were associated with lower high-density lipoprotein-cholesterol (HDL-C) (delta = - 0.07 mmol/ 1, p = 0.03) and a trend towards increased triglycerides (delta = 0.25 mmol/ 1, p = 0.07). In women, a trend towards the high triglyceride, low HDL-C phenotype was evident (delta = - 0.02 mmol/1 for HDL-C and delta = 0.14 mmol/l for triglycerides, respectively). Cumulative analysis of other studies of male carriers of the D9N and N291S revealed higher levels of triglycerides (D291N; 2.60(1.85) mmol/l vs. 1.62(1.18) mmol/l: p < 0.0001) (D9N; 1.94 (1.19) mmol/l vs. 1.74(1.17) mmol/l: p < 0.001) and lower HDL-C (N291S; 1.04(0.32) mmol/l vs. 1.15(0.28) mmol/l: p < 0.0001) (D9N; 1.08(0.24) mmol/l vs. 1.16(0.28) mmol/l: p < 0.0001). In females, results differed with higher TG levels (N291S; 1.70(0.99) mmol/l vs. 1.10(0.63) mmol/l: p < 0.001) (D9N; 1.08(0.76) mmol/l vs. 0.96(0.51) mmol/l: p < 0.01) and lower HDL-C levels (N291S; 1.27(0.33) mmol/l vs. 1.51(0.32) mmol/l: p < 0.0001); however, the HDL-C levels for D9N carriers were similar to non-carriers (D9N; 1.52(0.29) mmol/l vs. 1.53(0.35) mmol/l: p = 0.83). Our data provide evidence that common variants of the LPL gene are significant modulators of lipid and lipoprotein levels in both men and women.     

Genetic diversity of the Kaposi's sarcoma herpesvirus K1 protein in AIDS-KS in Zimbabwe.

BACKGROUND: Kaposi's sarcoma-associated herpesvirus (KSHV) encodes genetically diverse K1 alleles which have unique geographic distributions. Little is known about K1 genetic diversity in Zimbabwe where acquired immunodeficiency syndrome-associated KS (AIDS-KS) is epidemic. OBJECTIVE: Evaluate K1 diversity in Zimbabwe and compare Zimbabwean K1 diversity to other areas in Africa. STUDY DESIGN: K1 nucleotide sequence was determined for AIDS-KS cases in Zimbabwe. K1 references sequences were obtained from Genbank. RESULTS: Among 65 Zimbabwean AIDS-KS cases, 26 (40%) were K1 subtype A and 39 (60%) were subtype B. Zimbabwean subtype A sequences grouped only with African intratype A5 variants. Zimbabwean subtype B sequences grouped with multiple intratype African variants: 26 B1 (26%), four B3 (6%) and nine highly divergent B4 (14%). Zimbabwean subtype B had a lower synonymous to nonsynonymous mutation ratio (median 0.59 versus 0.66; P=0.008) and greater distance to the most recent common ancestor (median 0.03 versus 0.009; P<0.001) compared to subtype A. Within the B subgroup, the distribution of intratype B variants differed in Zimbabwe and Uganda (P=0.004). CONCLUSIONS: Greater positive selection and genetic diversity in K1 subtype B compared to subtype A5 exist in Zimbabwe. However, there were no significant associations between K1 subtype and the clinical or demographic characteristics of AIDS-KS cases.     

Tipranavir resistance associated mutations in protease inhibitor-na?ve patients with HIV-1 subtype A/E infection

BACKGROUND: Tipranavir-resistance associated mutations (TPV-RAMs) are often observed among patients with HIV-1 subtype A/E infection. Data regarding TPV resistance in subtype A/E is still limited. OBJECTIVES: To determine the prevalence of TPV-RAMs among protease inhibitor-na?ve, HIV-1 subtype A/E infected patients. STUDY DESIGN: Genotypic resistance testing was conducted among HIV-1-infected patients who were PI-na?ve. RESULTS: We studied 112 patients (mean age, 40.7 years; 58% male). Median CD4 cell count and HIV-1 RNA were 192cells/mm(3) and 4.2logcopies/mL, respectively. Ninety-three patients (83%) infected with subtype A/E; the others had subtype B. The most common TPV-RAMs were M36I (88%), H69K (61%), and I13V (48%). Median number of TPV-RAMs was 3 mutations. Patients with subtype A/E had higher prevalence of I13V (54% vs. 21%, P=0.011), M36I (96% vs. 53%, P<0.001), H69K (68% vs. 26%, P=0.001), and >2 TPV-RAMs (62% vs. 21%, P=0.002). In multivariate analysis, only subtype A/E was associated with the occurrence of >2 TPV-RAMs (OR 9.83; 95%CI, 1.95-39.57; P=0.006). CONCLUSIONS: TPV-RAMs previously described by IAS-USA are commonly observed in PI-na?ve patients with HIV-1 subtype A/E infection. Further studies to define virologic response of subtype A/E to TPV and clinical validation of TPV-RAMs in HIV-1 subtype A/E are essentially needed.     

Adaptation of the ultrasensitive HIV-1 p24 antigen assay to dried blood spot testing

Implementation of molecular tests for the assessment of pediatric HIV-1 infection in resource-limited countries is difficult because of technical complexity and costs. Alternatives like the ultrasensitive HIV-1 p24 antigen enzyme-linked immunosorbent assay have therefore been proposed. We have now adapted this test to dried blood spot (DBS) plasma p24 antigen (p24). High background activity was recognized as originating from endogenous peroxidase and eliminated by H2O2 quenching. The assay was evaluated with 72 pediatric specimens from Tanzania and with 210 pediatric or adult specimens from Switzerland. A real-time polymerase chain reaction assay for DBS DNA and/or plasma RNA identified HIV-1 infection in 38 Tanzanian children. HIV-1 subtypes included 18 C, 9 A1, 8 D, 1 AC, 1 J-like, and 1 unidentified. The detection rates for the different assays were as follows: DBS-p24, 32 (84%) of 38 samples; DBS DNA, 30 (79%) of 38 samples; plasma-p24, 23 (85%) of 27 samples; and plasma RNA, 30 (100%) of 30 samples. False-negative DBS-p24 was associated with subtype D (P < 0.01). DBS-p24 detection for non-D subtypes was 93% (95% confidence interval: 81% to 99%), and for subtype C, it was 94% (95% confidence interval: 76% to 99%). Specificity among 193 HIV-negative DBS samples was 100%. Correlation of DBS-p24 and plasma-p24 concentrations was excellent (R = 0.83, P < 0.0001). DBS-p24 is thus a promising alternative to molecular tests for HIV-1 in subtype C regions. It should now be evaluated in large studies of children for accurate assessment of diagnostic sensitivity.     

Persistence of nevirapine exposure during the postpartum period after intrapartum single-dose nevirapine in addition to zidovudine prophylaxis for the prevention of mother-to-child transmission of HIV-1

OBJECTIVE: To determine nevirapine (NVP) plasma levels during the postpartum period after a single intrapartum NVP dose for the prevention of mother-to-child transmission. METHODS: Plasma samples at delivery and during days 8 to 45 postpartum were obtained from HIV-infected Thai women who received an intrapartum NVP dose in the Perinatal HIV Prevention Clinical Trial-2 (PHPT-2) for the prevention of perinatal HIV transmission. These data were combined with NVP concentration data from 2 phase 1 studies of NVP for a population analysis. RESULTS: The median NVP level fell to 68 ng/mL (range: <50-228, n = 43) 8 to 14 days after dosing and to 51 ng/mL (range: <50-166, n = 25) between 15 and 21 days. During the second and third weeks postpartum, NVP levels were below the limit of quantitation in 23% and 44% of samples, respectively. Between 21 and 45 days, no sample had a quantifiable NVP concentration. A simulation derived from the population analysis predicts that NVP concentration falls to less than 10 ng/mL in 5% of women by 11 days, in 50% of women by 17.5 days, and in 95% of women by 28 days. CONCLUSIONS: Significant NVP concentrations remained for up to 20 days in these Thai women. To ensure that coverage is maintained until NVP concentrations fall to nonsuppressive levels, 1 month of additional antiretroviral treatment after delivery should be considered to prevent the emergence of resistant viruses.     

Risk of HIV-1 transmission by breastfeeding among mothers infected with recombinant and non-recombinant HIV-1 genotypes

BACKGROUND: Viral genotype and intersubtype recombination may influence the rate and/or timing of mother-to-child HIV-1 transmission. METHODS: We determined the HIV-1 subtype of the C2-C5 env and 5'LTR regions from milk and blood samples of 61 Tanzanian mothers who transmitted the virus through breastfeeding and their HIV-1 positive non-transmitting controls. Cases and controls were matched on infant's age at sample collection. All mothers resided in Dar es Salaam, Tanzania. RESULTS: Most infections among cases were due to recombinant viruses (41.0%), followed by HIV-1 subtype A (26.2%), subtype D (19.7%), and subtype C (13.1%). In multivariate analysis including maternal CD4+ cell counts, HIV disease stage, and proviral load in breast milk, the odds of breast milk transmission were 7.2 times higher if the mother carried an intersubtype recombinant genome in comparison to a subtype C virus (p=0.02). Viruses with recombinant LTRs were 4.9 times more likely to be transmitted through breastfeeding than viruses with non-recombinant LTRs of subtype A, C or D combined (p=0.01). CONCLUSIONS: This suggested that intersubtype recombinant genomes, and especially recombination within the LTR, might render HIV-1 more fit for transmission via breast milk in comparison with non-recombinant subtypes A, C, and D.     

Surveillance of HIV-1 subtypes among heterosexuals in England and Wales, 1997-2000

The molecular diversity and demographic characteristics among 976 anti-HIV-1-positive heterosexuals attending 15 sexually transmitted infection (STI) clinics participating in an unlinked anonymous HIV prevalence serosurvey in England and Wales during 1997-2000 were investigated. Subtypes were assigned by heteroduplex mobility assay or sequencing of the p17/p24 region of gag and the V3/V4 region of env and by sequencing of the protease gene. Overall, there was no significant change in the subtype distribution, with subtype C accounting for the majority (32%) of subtyped infections. Subtypes B (29%), A (12%), circulating recombinant forms (CRFs, 9%), unique recombinant forms (URFs, 8%), and subtypes D-H (8%) were also detected. Thirty-nine percent of infections in men were with subtype B, whereas subtype C was most common (38%) in women. Logistic regression analyses showed the relative risk (RR) of infection with a non-B subtype, compared with subtype B, to be greater in African-born individuals (RR = 28.9, P < 0.01), among newly diagnosed infections (RR = 3.4, P < 0.01), and in women (RR = 2.4, P < 0.01). These findings indicate a high level of genetic diversity among HIV-infected heterosexual STI clinic attendees in England and Wales. Recently, subtype C has become most prevalent, particularly in younger age groups, suggesting recent acquisition of this viral strain. The high proportion of non-B, CRF, and URF infections among UK-born individuals is consistent with mixing between migrants and UK-born individuals in England and Wales. As migration patterns change, continued monitoring of HIV genetic diversity will aid understanding of transmission patterns.