Prevalence of drug resistance and newly recognised treatment-related substitutions in the HIV-1 reverse transcriptase and protease genes from HIV-positive patients naïve for anti-retrovirals

The aim of this study was to assess the prevalence of genetic changes in either the HIV reverse transcriptase (RT) or protease (Pro) genes in a cohort of patients naïve for anti-retroviral therapy. Of 61 patients, 43 (70.5%) were infected with HIV strains harbouring at least one resistance-related mutation, with 41 (67.2%) harbouring newly recognised treatment-related mutations. Among the 61 patients, the prevalence of specific mutations in the RT gene was as follows: 39A, 1.6%; 43E, 1.6%; and 228H, 1.6%. The prevalence of specific mutations in the Pro gene was as follows: 11I, 1.6%; 13V, 26.2%; 35D, 19.6%; 45R, 1.6%; 58E, 1.6%; 62V, 31%; 72V, 11.4%; 72M, 6.5%; 72T, 3.2%; 75I, 1.6%; and 89M, 13%. A higher prevalence of newly recognised mutations was found in strains from patients infected through sexual practices (30/36 = 83.4% vs. 11/25 = 44%; p 0.0023; OR 10.91; 95% CI 3.14-40.39). These findings support the use of resistance testing in patients naïve for anti-retroviral therapy, and suggest that the possible impact of newly recognised treatment-related mutations on clinical outcome requires further investigation.

Predictors of long-term immunological outcome in rebounding patients on protease inhibitor-based HAART after initial successful virologic suppression: implications for timing to switch

OBJECTIVE

To assess predictive factors of long-term immune restoration in patients who started protease inhibitor (PI)-based HAART and experienced virological rebound after initial complete success.

METHOD

A retrospective longitudinal analysis of all HIV-infected patients who started their first PI-based HAART and reached viral load below 500 copies/mL was carried out in a large academic center in Italy. Patients were classified either as complete virologic responder (CR) or rebounders (REB) when confirmed plasma viremia was detected thereafter. Immunological outcome was the area under the curve (AUC) of the absolute CD4+ cell count change since the 8th month after treatment initiation (CD4+ T-cell AUC). Association between baseline characteristics, virological outcome, and CD4+ T-cell AUC was assessed by univariate and multivariate analysis.

RESULTS

There were 374 patients who were included in the study. Mean follow-up was 30.2 months. There were 226/374 patients (60.4%) who remained CR while 148/374 (39.6%) presented at least one rebound (REB). Among REB patients, complete viral suppression was regained in 15/42 (35.7%) and 50/106 (47.1%) patients who underwent therapy changes or not, respectively. When multiple linear regression was carried out, previous nucleoside reverse transcriptase inhibitor (NRTI) experience and baseline CD4+ cell count below 350 cells/muL did not impair long-term immune restoration. The occurrence of rebound, its duration (> 18 months), and its magnitude (peak of viral load > 10,000 copies/mL) were independent negative prognostic factors.

CONCLUSION

The occurrence of viral rebound is independently associated with significantly impaired long-term immunological restoration. The magnitude of viral rebound (< 10,000 copies/mL) and its duration (< 18 months) may be useful to identify those rebounding patients who may still profit from maintaining the current failing therapy if a more aggressive approach may be expected to be deleterious for tolerability reasons or lack of options.

Naive CD4+ T lymphocytes express high levels of Bcl-2 after highly active antiretroviral therapy for HIV infection

The mechanism causing the increasing number of peripheral T cells after highly active antiretroviral therapy (HAART) is still unclear. The bcl-2 oncogene prevents spontaneous apoptosis (SA) in lymphocytes. Spontaneous apoptosis could be a determinant of HIV immunodeficiency and can be reversed by HAART including protease inhibitors (PI-HAART). The aims of our study were to measure Bcl-2 protein expression in memory (CD45RO+) and naive (CD45RO-) CD4+ and CD8+ T lymphocytes of HIV+ patients and to correlate it with efficacy of PI-HAART. Forty-nine HIV+ patients (cases) and 26 HIV- individuals (controls) were evaluated. Patients receiving PI-HAART, and who had undetectable HIV plasma viral load (VL-, n = 21), had higher levels of Bcl-2 than did VL+ patients (n = 28), both in CD4+ cells (p < 0.0001) and in CD8+ cells (p < 0.001). VL+ patients had lower Bcl-2 levels than did controls in CD8+ cells (p = 0.02), but not in CD4+ cells (p > 0.05). Interestingly, VL- patients had higher Bcl-2 expression than did controls both in CD4+ cells (p < 0.0001) and in CD8+ cells (p = 0.03). In a subcohort of the same patients, Bcl-2 was significantly higher in VL- patients (n = 10) than in controls (n = 12), both in naive CD4+ cells (p < 0.0001) and in naive CD8+ cells (p = 0.01). Naive CD4+ cells had higher Bcl-2 expression in VL- than in VL+ patients (p = 0.01). In a subsequent longitudinal study of nine HIV patients, naive CD4+ cells increased after effective PI-HAART (p = 0.03), which paralleled an increase in Bcl-2 expression in the same cells (p = 0.02). In conclusion, upregulation of bcl-2 could be a mechanism of immune reconstitution of naive CD4+ T cells induced by PI-HAART.