Prevalence of multiple dideoxynucleoside analogue resistance (MddNR) in a cohort of Italian HIV-1 seropositive patients extensively treated with antiretroviral drugs

Polymorphic mutations associated with the emergence of the multinucleoside/tide resistance mutations 69 insertion and Q151M

BACKGROUND

We hypothesized that polymorphic mutations exist that are associated with the emergence of the multinucleoside resistance mutations (MNR), 69 insertion and Q151M.

METHODS

The Swiss HIV Cohort Study was screened, and the frequencies of polymorphic mutations in HIV-1 (subtype B) were compared between patients detected with the 69 insertion (n = 17), Q151M (n = 29), ≥2 thymidine analogue mutations (TAM) 1 (n = 400) or ≥2 TAM 2 (n = 249). Logistic regressions adjusted for the antiretroviral treatment history were performed to analyze the association of the polymorphic mutations with MNR.

RESULTS

The 69 insertion and TAM 1 were strongly associated and occurred in 94.1% (16 of 17) together. The 69 insertion seemed to emerge as a consequence of the TAM 1 pathway (median years until detection: 6.8 compared with 4.4 for ≥2 TAM 1, P Wilcoxon = 0.009). Frequencies of 8 polymorphic mutations (K43E, V60I, S68G, S162C, T165I, I202V, R211K, F214L) were significantly different between groups. Logistic regression showed that F214L and V60I were associated with the emergence of Q151M/TAM 2 opposed to 69 insertion/TAM 1. S68G, T165I, and I202V were associated with Q151M instead of TAM 2.

CONCLUSIONS

Besides antiretroviral therapy, polymorphic mutations may contribute to the emergence of specific MNR mutations.

Predictors for the emergence of the 2 multi-nucleoside/nucleotide resistance mutations 69 insertion and Q151M and their impact on clinical outcome in the Swiss HIV cohort study

The 69 insertion and Q151M mutations are multi-nucleoside/nucleotide resistance mutations (MNR). The prevalence among 4078 antiretroviral therapy (ART)-experienced individuals was <1.3%. Combined ART fully prevented MNR in subtype B infections. Case-control studies were performed to identify risk factors. Control subjects were patients with ≥ 3 thymidine-analogue mutations. The 69 insertion study (27 control subjects, 14 case patients) identified didanosine exposure as a risk (odds ratio, 5.0 per year; P = .019), whereas the Q151M study (which included 44 control subjects and 25 case patients) detected no associations. Following detection, individuals with Q151M tended to have lower suppression rates and higher mortality rates, relative to control subjects. Additional studies are needed to verify these findings in non-subtype B infections.

Conflicting interpretations of the prevalence of mutations associated with drug resistance in antiviral naïve HIV-1 patients with acute and chronic infection

The routine determination of drug resistance in newly HIV-1 infected individuals records a potential increase in transmissions of drug-resistant variants. Plasma samples from 38 individuals classified as newly infected (seroconversion time <12 months) and twenty four individuals with an established infection (seroconversion time ranging from 3 to 10 years) were analyzed for the presence of mutations by Trugene HIV-1 genotyping assay and Virtual phenotype. Results on the newly infected and the chronically infected individuals showed a limited number of relevant mutations associated with substantial resistance to reverse transcriptase and protease inhibitors. In particular, three patients (4.8%) carried viral major mutations (T69D and M41L) associated with resistance to reverse transcriptase inhibitors, whereas only one showed the presence of M46L, which is correlated with partial resistance to some protease inhibitors. The clinical interpretation based on different approaches to monitor resistance showed that the Virconet interpretation was less grave than Trugene, suggesting that these interpretations need standardization for the currently used sequencing methods and that they may be associated with different outcomes when eventually are used.

Q151M-mediated multinucleoside resistance: prevalence, risk factors, and response to salvage therapy

Among 470 patients with acquired immune deficiency syndrome and/or human immunodeficiency virus infection (HIV/AIDS) who underwent genotype resistance testing (GRT) after the failure of therapy, 17 (3.6%) harbored the Q151M mutation. The Q151M mutation was associated with younger age, lower CD4(+) lymphocyte count, higher HIV RNA level, and treatment with >2 pre-GRT regimens. By contrast, the Q151M mutation was inversely associated with lamivudine administration. A full reversion of the Q151M mutation was observed in 5 of 5 patients who underwent treatment interruption after GRT. The reversion was followed by a response to salvage therapy in 4 (80%) of 5 patients.

Mutation patterns of the reverse transcriptase genes in HIV-1 infected patients receiving combinations of nucleoside and non nucleoside inhibitors

A genotyping assay was used to define human immunodeficiency virus type 1 (HIV-1) reverse transcriptase codons in plasma samples from 80 HIV-1 patients extensively treated with two nucleoside reverse transcriptase (zidovudine and lamivudine) and one non nucleoside reverse transcriptase (nevirapine) inhibitor. The frequencies of T215S/Y/F, M41L, D67N, L210W K70R, K219Q mutations, detectable in plasma samples, conferring resistance to zidovudine were 61.2, 56.2, 36.2, 31.5, 27.5 and 17.5%, respectively. Mutations (M184V or M184I) conferring resistance to lamivudine were detected in an extremely high percentage of patients (61%). Among mutations correlated to high (K103N, V106A, Y181C/I, Y188C/H/L, G190A/C/E/Q/S/T) or moderate (V108I, V118I) levels of nevirapine resistance, the predominant amino acid change was a substitution at 103 codon, present in 24 of 80 samples tested. Finally Q151M, the marker mutation able to confer resistance to all nucleoside analogues, was detected in seven patients with a viral load of between 1 x 10(4) and 9 x 10(4) HIV-1 RNA copies/ml. The relationship between the genotype and the viral load showed that the incidence of some specific mutations [M41L, T215Y (correlated to zidovudine resistance) and K103N (correlated to all NNRTIs drugs)] significantly (P=0.001) increased with higher viral load. Our results, albeit limited to a small cohort, showed a high frequency of mutations correlated to drugs in use, suggesting a need for therapeutic change in the near future and demonstrating that the development of genotyping tests helps to guide the therapeutic management of HIV-1 infected people. Our data highlight the dangers of selecting antiretroviral therapy without previous antiretroviral drug testing. Although the cost of these assays is a concern, prescribing inefficacious drugs could create serious problems for HIV-1 patients.

Prevalence and virologic consequences of HIV-1 genotype mutations detected in a cohort of 161 Italian patients receiving a nelfinavir-based highly active antiretroviral therapy

A cross-sectional study was carried out in our tertiary care hospital between January 1998 and December 2001. All 161 consecutive patients naive to nelfinavir and who had received a nelfinavir-based highly active antiretroviral therapy (HAART) of at least 24-week duration were extrapolated from the 802 adult HIV-infected subjects treated with antiretroviral therapy. All cases of virologic failure were considered and viral genotyped. Virologic failure occurred in 80 out of 161 nelfinavir-treated patients, all belonging to the experienced group. On the whole, only 11 patients (7%) developed the D30N substitution, whose 6 was in association with the N88D mutation. Among the 80 failed patients, the M184V mutation was detected in 52 (65%), while only 7 patients showed simultaneously the M184V, T215Y and K103N substitutions. In our HIV-infected population receiving a nelfinavir-based HAART, the D30N mutation has shown a low absolute frequency, while the detection of M184V substitution and the simultaneous occurrence of M184V, T215Y and K103N mutations were related to a more favorable virological response.

Development of drug resistance in HIV-1 patients receiving a combination of stavudine, lamivudine and efavirenz

The study evaluated the development of drug resistance in a group of HIV-1 patients. After failure to respond to previous therapy with two non-nucleoside reverse transcriptase inhibitors (NNRTIs), as assessed by the presence of a rebound in viral load or a constant high level of HIV plasma viraemia, the patients were treated with a combination of stavudine, lamivudine and efavirenz (EFV). Results showed that viruses carrying primary mutations, usually K103N, T215Y and M41L, presented higher levels of HIV-1 RNA, suggesting an association between a precise mutation pattern and treatment failure.