Genotypic testing on HIV-1 DNA as a tool to assess HIV-1 co-receptor usage in clinical practice: results from the DIVA study group.

PURPOSE: We have developed a sequencing assay for determining the usage of the genotypic HIV-1 co-receptor using peripheral blood mononuclear cell (PBMC) DNA in virologically suppressed HIV-1 infected patients. Our specific aims were to (1) evaluate the efficiency of V3 sequences in B versus non-B subtypes, (2) compare the efficiency of V3 sequences and tropism prediction using whole blood and PBMCs for DNA extraction, (3) compare the efficiency of V3 sequences and tropism prediction using a single versus a triplicate round of amplification. RESULTS: The overall rate of successful V3 sequences ranged from 100 % in samples with >3,000 copies HIV-1 DNA/10(6) PBMCs to 60 % in samples with <100 copies total HIV-1 DNA /10(6) PBMCs. Analysis of 143 paired PBMCs and whole-blood samples showed successful V3 sequences rates of 77.6 % for PBMCs and 83.9 % for whole blood. These rates are in agreement with the tropism prediction obtained using the geno2pheno co-receptor algorithm, namely, 92.1 % with a false-positive rate (FPR) of 10 or 20 % and of 96.5 % with an FPR of 5.75 %. The agreement between tropism prediction values using single versus triplicate amplification was 98.2 % (56/57) of patients using an FPR of 20 % and 92.9 % (53/57) using an FPR of 10 or 5.75 %. For 63.0 % (36/57) of patients, the FPR obtained via the single amplification procedure was superimposable to all three FPRs obtained by triplicate amplification. CONCLUSIONS: Our results show the feasibility and consistency of genotypic testing on HIV-1 DNA tropism, supporting its possible use for selecting patients with suppressed plasma HIV-1 RNA as candidates for CCR5-antagonist treatment. The high agreement between tropism prediction by single and triple amplification does not support the use of triplicate amplification in clinical practice.

Prevalence of etravirine (ETR)-RAMs at NNRTI failure and predictors of resistance to ETR in a large Italian resistance database (ARCA).

The prevalence of drug resistance associated with the failure of non-nucleoside reverse transcriptase inhibitor (NNRTI)-based regimens and the predictors of resistance to Etravirine (ETR) were assessed in 2854 subjects: 39 < 18 (paediatric) and 2815 ≥ 18 (adult) years old. These subjects failed to respond to their current NNRTI treatment, were three-class experienced and had been exposed to NNRTI for ≥3 months. A total of 1827 adult (64.9%) and 32 paediatric subjects (82.1%) harboured the virus with at least one ETR mutation. V179I, Y181C and G190A were the most frequent mutations in both groups. A significantly increased risk of ETR resistance with all three algorithms (Monogram (MGR) >3, Tibotec (TBT) >2 and enhanced MGR (ENH) ≥4) emerged in the paediatric population. Multivariate analysis revealed an increased risk of developing TBT >2 for NNRTI exposure, ENH ≥4 for NNRTI and EFV exposure in paediatric subjects; NVP exposure and higher (≥3.5 log10) HIV-RNA values for all three algorithms in adult subjects, whereas CD4 ≥ 200/µL appeared to be protective. The risk of being ETR resistant was more than doubled for paediatric vs. adult subjects, probably due to a more extensive use of NNRTI and an incomplete virological control.

Prevalence of HIV-1 integrase mutations related to resistance to dolutegravir in raltegravir naïve and pretreated patients.

The prevalence of HIV-1 integrase mutations related to resistance to the next-generation integrase inhibitor (INI), dolutegravir (DTG), was assessed in 440 INI-naïve subjects and in 120 patients failing a raltegravir (RTG)-containing regimen. Of the mutations selected by DTG in vitro, S153FY was not detected in any isolate while L101I and T124A were highly prevalent in both groups and significantly associated with non-B subtype. RTG-selected double and triple mutants, mostly the G140S/Q148H variant, were detected in only 32 (26.7%) RTG-treated patients. As L101I and T124A do not appear to exert any major effect in vivo and double and triple mutants resistant to DTG are infrequently selected by RTG, DTG can be effectively used in INI-naïve patients and may retain activity in many patients failing RTG.

Human immunodeficiency virus-1 B and non-B subtypes with the same drug resistance pattern respond similarly to antiretroviral therapy.

We analysed the 12-week virological response to protease inhibitor (PI) or non-nucleoside reverse transcriptase inhibitor (NNRTI) therapy in 1108 patients carrying B or non-B human immunodeficiency virus (HIV)-1 subtypes with matched resistance mutation patterns. Response rates were not significantly different for non-B and B subtypes stratified for treatment status (51.5% vs. 41.5% in naïve patients; 46.7% vs. 38.7% in experienced patients) or regimens (46.9% vs. 39.7% with PI; 56.7% vs. 40% with NNRTI). No difference in response was detected in patients harbouring B and non-B subtypes with any resistance profile. Further studies are advisable to fully test this approach on larger datasets.

Update on emergence of HIV-1 resistance to antiretroviral drug classes in an Italian national database: 2007-2009.

We analysed trends of human immunodeficiency virus type 1 (HIV-1) drug resistance during 2007-2009 in the Italian national HIV drug resistance database 'ARCA'. Prevalence of resistance in each year was examined on the basis of the presence of major International AIDS Society-2009 mutations. Predictors of resistance were analysed by multivariable logistic regression. Nine hundred and sixty-six patients were selected. Resistance to nucleoside reverse transcriptase inhibitors and protease inhibitors showed a significant decline with respect to previous surveys. Resistance to any class of drug and three drug classes remained stable. Independent predictors of three-class resistance were the number of treatment regimens experienced, prior suboptimal nucleoside reverse transcriptase inhibitor therapy and the current use of ritonavir-boosted protease inhibitors.

Changing patterns in HIV-1 non-B clade prevalence and diversity in Italy over three decades.

BACKGROUND: HIV-1 non-B subtypes have recently entered Western Europe following immigration from other regions. The distribution of non-B clades and their association with demographic factors, over the entire course of the HIV-1 epidemic, have not been fully investigated in Italy. METHODS: We carried out a phylogenetic analysis of HIV-1 pol sequences derived from 3670 patients followed at 50 Italian clinical centres over nearly three decades. RESULTS: Overall, 417 patients (11.4%) carried non-B subtypes. The prevalence of non-B strains increased from 2.6% in 1980-1992 to 18.9% in 1993-2008 (P<0.0001) in a subset of 2479 subjects with a known year of diagnosis. A multivariate analysis on a subset of 1364 patients for whom relevant demographic data were available indicated that African ethnicity, heterosexual route of infection and year of diagnosis were independently associated with non-B HIV-1 infection (P ≤ 0.0001). All pure subtypes, except for clade K, and seven circulating recombinant forms were detected, accounting for 56.6 and 34.1% of the non-B infections, respectively. The F1 subtype was the most prevalent non-B clade among Europeans and was acquired heterosexually in half of this patient population. Unique recombinant forms accounted for 9.4% of the non-B sequences and showed a B/F1 recombination pattern in one-third of cases. CONCLUSIONS: The circulation of non-B clades has significantly increased in Italy in association with demographic changes. Spread of the F1 subtype and B/F recombinants appears to predominate, which may result in a redistribution of the relative proportions of the different strains, and this could lead to overlapping epidemics. Thus, the HIV-1 landscape in Italy may in future be distinct from that of the rest of Europe.