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Background: Surveillance of HIV-1 drug resistance in antiretroviral-treated patients is important from the public health perspective of the spread of resistance and to evaluate the proportion of patients for whom new drugs are needed., Methods: Patients were consecutively included in 28 centers in France and 1 center in Switzerland if they had a viral load measurement performed in June 2004, with a result >or=1,000 copies/mL. Reverse transcriptase, protease, and gp41 genes were sequenced, and resistance mutations were reported as listed on the Web site ( www.iasusa.org). The genotypic resistance results were interpreted by the Agence Nationale de Recherches sur le SIDA et les Hepatites Virales (ANRS) and Stanford algorithms., Results: The 498 patients included had been exposed to 9 (interquartile ratio [IQR]: 6 to 12) antiretroviral drugs. Patients' viruses harbored 4 nucleoside reverse transcriptase inhibitor (IQR: 1 to 6) and 4 protease inhibitor (PI; IQR: 2 to 8) resistance mutations, whereas 44% had at least 1 nonnucleoside reverse transcriptase inhibitor resistance mutation. The frequency of resistance to at least 1 drug was 88% with the ANRS algorithm and 83% with the Stanford algorithm. The frequencies of complete resistance to 1, 2, and 3 classes of drugs were 37%, 15%, and 4%, respectively, with the ANRS algorithm and 27%, 23%, and 24%, respectively, with the Stanford algorithm. The most important differences between algorithms were for PIs. Using the ANRS algorithm and extrapolation on the whole French database, 19% of all treated patients could contribute to the spread of resistance and 4% had complete resistance to 2 classes of antiretroviral drugs., Conclusions: The observed patterns of resistance are linked to a long-lasting history of antiretroviral therapy. The frequency of multiresistance can vary according to the interpretation systems.

The genotypic inhibitory quotient (GIQ) has been proposed as a way to integrate drug exposure and genotypic resistance to protease inhibitors and can be useful to enhance the predictivity of virologic response for boosted protease inhibitors. The aim of this study was to evaluate the predictivity of the GIQ in 116 protease inhibitor-experienced patients treated with lopinavir-ritonavir. The overall decrease in human immunodeficiency virus type 1 (HIV-1) RNA from baseline to month 6 was a median of -1.50 log(10) copies/ml and 40% of patients had plasma HIV-1 RNA below 400 copies/ml at month 6. The overall median lopinavir study-state C(min) concentration was 5,856 ng/ml. Using univariate linear regression analyses, both lopinavir GIQ and the number of baseline lopinavir mutations were highly associated with virologic response through 6 months. In the multivariate analysis, only lopinavir GIQ, baseline HIV RNA, and the number of prior protease inhibitors were significantly associated with response. When the analysis was limited to patients with more highly mutant viruses (three or more lopinavir mutations), only lopinavir GIQ remained significantly associated with virologic response. This study suggests that GIQ could be a better predictor of the virologic response than virological (genotype) or pharmacological (minimal plasma concentration) approaches used separately, especially among patients with at least three protease inhibitor resistance mutations. Therapeutic drug monitoring for patients treated by lopinavir-ritonavir would likely be most useful in patients with substantially resistant viruses.

Sera from 12 patients infected with human immunodeficiency virus and hepatitis B virus (HBV), on lamivudine as part of an antiretroviral therapy, were retrospectively analysed for the presence of HBV polymerase mutations by the line probe assay, INNO-LiPA HBV DR, and by the direct sequencing assay, TRUGENE HBV genotyping kit. Results at codons 180, 204 and 207 were compared for 44 samples. Full concordance was observed for 81.4% of the 129 analysed codons. Discordance involved only mixed populations: LiPA detected additional species in 19 codons and TRUGENE in five. Viral breakthrough occurred in seven patients, 12-33 months after lamivudine initiation. In five cases with close sampling available, both assays detected mutations before the rise in viral load, although earlier by LiPA for three patients. The time interval between the first mutant detection and viral escape ranged from 2 to 22 months. Mutations were detected in four of the five remaining patients: 1) at therapy initiation in a primary non-responder; 2) after 37 months, but replication became undetectable after tenofovir introduction; 3) transiently at 6 months by LiPA but treatment was ceased thereafter; 4) after 23 months but replication levels remained low during a 5-year follow-up. Interestingly, TRUGENE sequencing identified on late samples from three patients a variant carrying rtV173L plus rtL180M plus M204V mutations, having the in vitro characteristics of 'vaccine escape' mutants. Both assays appear to be valuable tools for the early detection of mutated HBV strains. The detection of genotypic therapeutic decision-making, although clinical or other virological factors may determine the rapidity of the viral breakthrough.