Predominance of CXCR4 tropism in HIV-1 CRF14_BG strains from newly diagnosed infections.

OBJECTIVES: R5-tropic viruses are associated with HIV-1 transmission and predominate during the early stages of infection. X4-tropic populations have been detected in ~50% of patients with late-stage disease infected with subtype B viruses. In this study, we compared the frequency of X4 tropism in individuals infected with HIV-1 CRF14_BG viruses, which have a V3 loop of subtype B, with a control group of individuals infected with subtype B viruses. METHODS: Sixty-three individuals infected with HIV-1 CRF14_BG (n = 31) or subtype B (n = 32) were studied. Similar proportions of newly diagnosed and chronically infected individuals were included in the subtype B and CRF14_BG groups. V3 sequences were obtained and coreceptor tropism was predicted using the Geno2pheno[coreceptor] algorithm. V3 net charge and 11/25 rules were also used for coreceptor prediction. RESULTS: Overall, X4 tropism was more frequent among individuals infected with CRF14_BG viruses (87.1%) than subtype B viruses (34.3%), a difference that was statistically highly significant (P = 0.00001). Importantly, the frequencies among newly diagnosed individuals were 90% and 13.3%, respectively (P = 0.0007). Characteristic amino acids in the V3 loop (T13, M14, V19 and W20) were identified at higher frequencies in CRF14_BG viruses (54%) than subtype B viruses (0%; P < 0.000001). CONCLUSIONS: CRF14_BG is the genetic form with the highest proportion of X4-tropic viruses reported to date in newly diagnosed and chronic infections. This suggests high pathogenicity for CRF14_BG viruses, potentially leading to rapid disease progression. CCR5 antagonists will be ineffective in most CRF14_BG-infected patients, even at early stages of infection.

HIV-1 transmission cluster with T215D revertant mutation among newly diagnosed patients from the Basque Country, Spain.

OBJECTIVE: To determine the introduction of HIV-1 genetic forms and to examine transmission clusters and resistance to antiretroviral inhibitors among newly diagnosed patients from the Basque Country, Spain, during 2004-2007. METHODS: A total of 261 samples, corresponding to 47.5% heterosexuals, 37.9% men who have sex with men (MSM), and 11.1% intravenous drug users were analyzed in protease and reverse transcriptase to examine phylogenetic relationships and drug resistance-associated mutations. RESULTS: Subtype B was detected in 220 (84.3%) samples and non-B subtype variants in 41 (15.7%) samples. Nearly half (47%) of the sequences grouped in transmission clusters. One of these comprised 14 individuals, 12 of them MSM, with the T215D revertan mutation. In largest transmission clusters, the percentage of MSM was higher than heterosexuals (P < 0.001). Resistance mutations were detected in 29 (11.1%) patients: 20 (7.6%) of them to nucleoside reverse transcriptase inhibitor; 6 (2.3%) to nonnucleoside reverse transcriptase inhibitor (NNRTI); and 1 each to protease inhibitors, protease inhibitor plus NNRTI, and nucleoside reverse transcriptase inhibitor plus NNRTI, respectively. CONCLUSIONS: Our findings underscore recommendations for HIV-1 genotyping in newly diagnosed patients not only to provide information on transmitted drug resistance as an issue in public health and as a guide to future therapy but also to document transmission clusters and to increase the necessary preventive measures.

Analysis of discrepancies in the interpretation of antiretroviral drug resistance results in HIV-1 infected patients of Basque Country, Spain.

BACKGROUND: Genotypic and phenotypic analysis of HIV-1 resistance mutations constitute one important point for providing guidelines in the choice of antiretroviral regimens and to design lines of rescue treatment for patients holding HIV-1 drug-resistant variants. However, some levels of discordance among them has been described. OBJECTIVES: (i) To compare the genotypic analysis of resistance mutations to reverse transcriptase (RT) and protease (PR) inhibitors by Stanford HIVdb program (http://hivdb.stanford.edu) (St-HIVdb), and genotype with quantitative phenotypic analysis (Virtual Phenotype, VircoNET). (ii) To identify drug resistance mutations associated with discrepant results. STUDY DESIGN: Five hundred HIV-1 infected patients were included in this study. RNA was extracted from plasma. RT and PR regions were amplified and sequenced using ABI-Prism DNA sequencing system. Sequences were corrected and assembled with Seqman and Bioedit computer programs. The corrected sequences were submitted to the Stanford HIV-Seq program (http://hivdb.stanford.edu) and to Virtual Phenotype (VircoNET). RESULTS: Discrepant cases were considered if results were high or intermediate resistant by Stanford HIV-Seq program and susceptible by Virtual Phenotype, being detected as follows: (i) nucleoside RT inhibitors (NRT): 31.7% (ABC), 31% (d4T), 29.5% (ddC), 27.6% (ddI), 14.3% (TDF) and 11.3% (ZDV) and to PR inhibitors: 8.8% (SQV), 5% (APV), 3.8% (NFV) and 3.2% (IDV). These discrepant results were related to the presence of thymidine analogue mutations (TAMs) and also to key resistance mutations to NRT inhibitors: 65R, 69D/N, 74V/I, 184V/I and 215Y/F. (ii) PR inhibitors: 82A/F/T/S, 84I and 90M. Concordant results were considered when the interpretations by both programs were coincident, being higher than 96.7% for non-NRT inhibitors. CONCLUSIONS: The detection of discrepant results to NRT inhibitors and PR inhibitors, including the analysis of sequences with key resistant mutations to some drugs, means that further investigation is necessary in order to establish which is the best interpretation system as antiretroviral therapy guide.