Sabine Yerly

Prevalence of Drug-Resistant HIV-1 Variants in Untreated Individuals in Europe: Implications for Clinical Management

BACKGROUND Infection with drug-resistant human immunodeficiency virus type 1 (HIV-1) can impair the response to combination therapy. Widespread transmission of drug-resistant variants has the disturbing potential of limiting future therapy options and affecting the efficacy of postexposure prophylaxis. METHODS We determined the baseline rate of drug resistance in 2208 therapy-naive patients recently and chronically infected with HIV-1 from 19 European countries during 1996-2002. RESULTS In Europe, 1 of 10 antiretroviral-naive patients carried viruses with > or = 1 drug-resistance mutation. Recently infected patients harbored resistant variants more often than did chronically infected patients (13.5% vs. 8.7%; P=.006). Non-B viruses (30%) less frequently carried resistance mutations than did subtype B viruses (4.8% vs. 12.9%; P<.01). Baseline resistance increased over time in newly diagnosed cases of non-B infection: from 2.0% (1/49) in 1996-1998 to 8.2% (16/194) in 2000-2001. CONCLUSIONS Drug-resistant variants are frequently present in both recently and chronically infected therapy-naive patients. Drug-resistant variants are most commonly seen in patients infected with subtype B virus, probably because of longer exposure of these viruses to drugs. However, an increase in baseline resistance in non-B viruses is observed. These data argue for testing all drug-naive patients and are of relevance when guidelines for management of postexposure prophylaxis and first-line therapy are updated.

Transmission of antiretroviral-drug-resistant HIV-1 variants

BACKGROUND Resistance of HIV-1 to antiretroviral drugs is the main cause of antiretroviral-treatment failure. We assessed the transmission of drug-resistant variants among individuals with primary HIV-1 infection. METHODS Population-based sequencing of the viral reverse-transcriptase and protease genes derived from plasma viral RNA was done in 82 consecutive individuals with documented primary HIV-1 infection from January, 1996, to July, 1998. Phenotypic resistance to protease inhibitors was assessed by recombinant virus assay in individuals with two or more mutations associated with resistance to protease inhibitors. FINDINGS Zidovudine-resistance mutations were detected in seven (9%) of 82 individuals. Mutations associated with resistance to other reverse-transcriptase inhibitors (RTIs) were detected in two individuals. Primary-resistance mutations associated with protease inhibitors (V82A, L90M) were detected in three (4%) of 70 individuals; two of these had also RTI-resistance mutations. Decreased sensitivity to three or four protease inhibitors was seen in three individuals, one of whom was infected with HIV-1 variants that harboured 12 mutations associated with resistance to multiple RTI and protease inhibitors. INTERPRETATION To introduce the best antiretroviral treatment, resistance testing should be done in recently HIV-1-infected individuals.

A controlled trial of zidovudine in primary human immunodeficiency virus infection.

BACKGROUND It is possible that antiretroviral treatment given early during primary infection with the human immunodeficiency virus (HIV) may reduce acute symptoms, help preserve immune function, and improve the long-term prognosis. METHODS To assess the effect of early antiviral treatment, we conducted a multicenter, double-blind, placebo-controlled trial in which 77 patients with primary HIV infection were randomly assigned to receive either zidovudine (250 mg twice daily; n = 39) or placebo (n = 38) for six months. RESULTS The mean time from the onset of symptoms until enrollment in the study was 25.1 days. Among the 43 patients who were still symptomatic at the time of enrollment, there was no appreciable difference in the mean (+/- SE) duration of the retroviral syndrome between the zidovudine group (15.0 +/- 4.1 days) and the placebo group (15.8 +/- 3.6 days). During a mean follow-up period of 15 months, minor opportunistic infections developed in eight patients: oral candidiasis in four, herpes zoster in two, and oral hairy leukoplakia in two. Disease progression was significantly less frequent in the zidovudine group (one opportunistic infection) than in the placebo group (seven opportunistic infections; P = 0.009 by the log-rank test). After adjustment for the base-line CD4 cell count, the patients treated with zidovudine had an average gain of 8.9 CD4 cells per cubic millimeter per month (95 percent confidence interval, -1.4 to 19.1) during the first six months of the study, whereas those receiving placebo had an average loss of 12.0 CD4 cells per cubic millimeter per month (95 percent confidence interval, 5.2 to 18.7), for a between-group difference of 20.9 CD4 cells per cubic millimeter per month (95 percent confidence interval, 8.5 to 33.2; P = 0.001). CONCLUSIONS Antiretroviral therapy administered during primary HIV infection may improve the subsequent clinical course and increase the CD4 cell count.

Acute Hiv infection: impact on the spread of Hiv and transmission of drug resistance

ObjectiveTo assess the impact of primary HIV infection (PHI) on the spread of HIV and the temporal trends in transmission of HIV drug resistance between 1996 and 1999 in Switzerland. MethodsSequencing of the genes for reverse transcriptase (RT) and protease was performed for 197 individuals with documented PHI. Phylogenetic analyses were confronted with epidemiological data. ResultsSignificant clustering was demonstrated for 29% of the RT sequences. All these cases occurred closely together in place and time; contact tracing demonstrated transmission at the time of PHI in 30% of them. Genotypic drug resistance was detected in 8.6% of PHI individuals in 1996, 14.6% in 1997, 8.8% in 1998 and 5.0% in 1999. Drug-resistant variants were identified in 11.3% of individuals infected by homosexual contacts, 6.1% by heterosexual contacts, 13% of intravenous drug users and more frequently in men (10.4%) than women (2.6%). Potential factors involved in the recent decrease of transmission of drug-resistant variants include increase of HIV non-B subtypes from 23% in 1996 to 35% in 1999 (only one non-B subtype had resistance mutations) and a steady increase of patients with undetectable viraemia as documented in Swiss HIV Cohort Study (10% in 1996 vs 53% in 1999). ConclusionsPhylogenetic and epidemiological analyses underline the impact of PHI in the spread of HIV. Moreover, this study indicates that drug resistance transmission may have decreased recently in Switzerland through the increased frequency of infection with HIV non-B subtypes and the steady increase of patients with undetectable viraemia.

Virological monitoring and resistance to first-line highly active antiretroviral therapy in adults infected with HIV-1 treated under WHO guidelines: a systematic review and meta-analysis

Antiretroviral-therapy rollout in resource-poor countries is often associated with limited, if any, HIV-RNA monitoring. The effect of variable monitoring on the emergence of resistance after therapy with commonly used drug combinations was assessed by systematic review of studies reporting resistance in patients infected with HIV with a CD4 count of fewer than 200 cells per muL treated with two nucleoside analogues (including a thymidine analogue) and a non-nucleoside reverse transcriptase inhibitor. 8376 patients from eight cohorts and two prospective studies were analysed. Resistance at virological failure to non-nucleoside reverse transcriptase inhibitors at 48 weeks was 88.3% (95% CI 82.2-92.9) in infrequently monitored patients, compared with 61.0% (48.9-72.2) in frequently monitored patients (p<0.001). Lamivudine resistance was 80.5% (72.9-86.8) and 40.3% (29.1-52.2) in infrequently and frequently monitored patients, respectively (p<0.001); the prevalence of at least one thymidine analogue mutation was 27.8% (21.2-35.2) and 12.1% (5.9-21.4), respectively (p<0.001). Genotypic resistance at 48 weeks to lamivudine, nucleoside reverse transcriptase inhibitors (thymidine analogue mutations), and non-nucleoside reverse transcriptase inhibitors appears substantially higher in less frequently monitored patients. This Review highlights the need for cheap point-of-care viral-load tests to identify early viral failures and limit the emergence of resistance.

CD4-guided scheduled treatment interruptions compared with continuous therapy for patients infected with HIV-1: results of the Staccato randomised trial.

BACKGROUND Stopping antiretroviral therapy in patients with HIV-1 infection can reduce costs and side-effects, but carries the risk of increased immune suppression and emergence of resistance. METHODS 430 patients with CD4-positive T-lymphocyte (CD4) counts greater than 350 cells per muL, and viral load less than 50 copies per mL were randomised to continued therapy (n=146) or scheduled treatment interruptions (n=284). Median time on randomised treatment was 21.9 months (range 16.4-25.3). Primary endpoints were proportion of patients with viral load less than 50 copies per mL at the end of the trial, and amount of drugs used. Analysis was intention-to-treat. This study is registered at ClinicalTrials.gov with the identifier NCT00113126. FINDINGS Drug savings in the scheduled treatment interruption group, compared with continuous treatment, amounted to 61.5%. 257 of 284 (90.5%) patients in the scheduled treatment interruption group reached a viral load less than 50 copies per mL, compared with 134 of 146 (91.8%) in the continued treatment group (difference 1.3%, 95% CI-4.3 to 6.9, p=0.90). No AIDS-defining events occurred. Diarrhoea and neuropathy were more frequent with continuous treatment; candidiasis was more frequent with scheduled treatment interruption. Ten patients (2.3%) had resistance mutations, with no significant differences between groups. INTERPRETATION Drug savings with scheduled treatment interruption were substantial, and no evidence of increased treatment resistance emerged. Treatment-related adverse events were more frequent with continuous treatment, but low CD4 counts and minor manifestations of HIV infection were more frequent with scheduled treatment interruption.

Phase 1 Trials of rVSV Ebola Vaccine in Africa and Europe.

BACKGROUND The replication-competent recombinant vesicular stomatitis virus (rVSV)-based vaccine expressing a Zaire ebolavirus (ZEBOV) glycoprotein was selected for rapid safety and immunogenicity testing before its use in West Africa. METHODS We performed three open-label, dose-escalation phase 1 trials and one randomized, double-blind, controlled phase 1 trial to assess the safety, side-effect profile, and immunogenicity of rVSV-ZEBOV at various doses in 158 healthy adults in Europe and Africa. All participants were injected with doses of vaccine ranging from 300,000 to 50 million plaque-forming units (PFU) or placebo. RESULTS No serious vaccine-related adverse events were reported. Mild-to-moderate early-onset reactogenicity was frequent but transient (median, 1 day). Fever was observed in up to 30% of vaccinees. Vaccine viremia was detected within 3 days in 123 of the 130 participants (95%) receiving 3 million PFU or more; rVSV was not detected in saliva or urine. In the second week after injection, arthritis affecting one to four joints developed in 11 of 51 participants (22%) in Geneva, with pain lasting a median of 8 days (interquartile range, 4 to 87); 2 self-limited cases occurred in 60 participants (3%) in Hamburg, Germany, and Kilifi, Kenya. The virus was identified in one synovial-fluid aspirate and in skin vesicles of 2 other vaccinees, showing peripheral viral replication in the second week after immunization. ZEBOV-glycoprotein-specific antibody responses were detected in all the participants, with similar glycoprotein-binding antibody titers but significantly higher neutralizing antibody titers at higher doses. Glycoprotein-binding antibody titers were sustained through 180 days in all participants. CONCLUSIONS In these studies, rVSV-ZEBOV was reactogenic but immunogenic after a single dose and warrants further evaluation for safety and efficacy. (Funded by the Wellcome Trust and others; ClinicalTrials.gov numbers, NCT02283099, NCT02287480, and NCT02296983; Pan African Clinical Trials Registry number, PACTR201411000919191.).

Impact of drug resistance mutations on virologic response to salvage therapy

OBJECTIVE To assess the prognostic significance of drug-associated mutations in the protease and reverse transcriptase (RT) genes on virological response to salvage therapy. PATIENTS All patients from four centres of the Swiss HIV Cohort Study who were switched, between February and October 1997, to nelfinavir plus other antiretroviral drugs following failure of highly active antiretroviral therapy (HIV-1 RNA >1000 copies/ml after > 3 months). METHODS Direct sequencing of RT and protease genes derived from plasma RNA was performed in 62 patients before salvage therapy. Baseline predictors (drug-resistance mutations, drug exposure, clinical and biological parameters) of virological response after 4-12 weeks of therapy were assessed by linear regression analyses. RESULTS Patients had been treated with RT inhibitors and protease inhibitors for a median duration of 35.6 and 12.2 months, respectively. Baseline median CD4 cell count was 113 x 10(6)/l and HIV-1 RNA 5.16 log10 copies/ml. The median decrease of HIV-1 RNA was 0.38 log10; 32% of the patients showed > 1 log10 decrease. At baseline, 90% of the patients had RT inhibitor-resistance mutations with a median number per patient of four (range, 0-7). Primary and secondary protease inhibitor-resistance mutations were detected in 69% and 89% of the patients, respectively. The median number of total protease inhibitor-resistance mutations per patient was four (range, 0-9). In univariate analysis, virological response to salvage therapy was associated with number of RT inhibitors, primary and secondary protease inhibitor-resistance mutations, history of protease inhibitor use (duration and number), but not with clinical stage, HIV-1 RNA level or CD4 cell count. After adjustment for all variables, the number of RT inhibitor plus protease inhibitor-resistance mutations was the only independent predictor. CONCLUSIONS In patients with advanced HIV infection, the virological response to salvage therapy containing nelfinavir is best predicted by the number of baseline RT inhibitor plus protease inhibitor-resistance mutations.

Minority Quasispecies of Drug-Resistant HIV-1 That Lead to Early Therapy Failure in Treatment-Naive and -Adherent Patients

BACKGROUND Early virological failure of antiretroviral therapy associated with the selection of drug-resistant human immunodeficiency virus type 1 in treatment-naive patients is very critical, because virological failure significantly increases the risk of subsequent failures. Therefore, we evaluated the possible role of minority quasispecies of drug-resistant human immunodeficiency virus type 1, which are undetectable at baseline by population sequencing, with regard to early virological failure. METHODS We studied 4 patients who experienced early virological failure of a first-line regimen of lamivudine, tenofovir, and either efavirenz or nevirapine and 18 control patients undergoing similar treatment without virological failure. The key mutations K65R, K103N, Y181C, M184V, and M184I in the reverse transcriptase were quantified by allele-specific real-time polymerase chain reaction performed on plasma samples before and during early virological treatment failure. RESULTS Before treatment, none of the viruses showed any evidence of drug resistance in the standard genotype analysis. Minority quasispecies with either the M184V mutation or the M184I mutation were detected in 3 of 18 control patients. In contrast, all 4 patients whose treatment was failing had harbored drug-resistant viruses at low frequencies before treatment, with a frequency range of 0.07%-2.0%. A range of 1-4 mutations was detected in viruses from each patient. Most of the minority quasispecies were rapidly selected and represented the major virus population within weeks after the patients started antiretroviral therapy. All 4 patients showed good adherence to treatment. Nonnucleoside reverse-transcriptase inhibitor plasma concentrations were in normal ranges for all 4 patients at 2 separate assessment times. CONCLUSIONS Minority quasispecies of drug-resistant viruses, detected at baseline, can rapidly outgrow and become the major virus population and subsequently lead to early therapy failure in treatment-naive patients who receive antiretroviral therapy regimens with a low genetic resistance barrier.

Travel and the spread of HIV-1 genetic variants.

HIV-1 comprises three groups, the main (M group), O (outlier) and N (non-M, non-O). The M group, divided into 11 subtypes, is responsible for the global HIV-1 pandemic. Recombination between M subtypes has resulted in the generation of multiple circulating recombinant forms (CRFs) consisting of mosaic lineages. Most subtypes and CRFs are represented in Africa, whereas predominance of one or a few subtypes was reported initially elsewhere. This finding reflects the African origin of the epidemic. In western countries, where the B subtype is predominant, there is a steep increase in non B-subtypes and CRFs, while new recombinants emerge worldwide. Travellers contribute to the spread of HIV-1 genetic diversity worldwide, and in the developing world migration of rural populations and civil war are additional contributing factors. The spreading of HIV-1 variants has implications for diagnostic, treatment, and vaccine development.