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Patients infected with HIV-1 with more than 1000 HIV-1 RNA copies/mL, who were genotyped within 3 months before starting stavudine and treated for at least 3 months with a stable stavudine-containing highly active antiretroviral therapy, were selected from our database to identify the determinants of response to stavudine. Nonresponse was defined as a failure to achieve HIV-1 RNA level of less than 400 copies/mL or a reduction of more than 2 log10 by week 12. Univariate logistic analysis was used to elicit the failure-associated reverse transcriptase mutations (scored 1 to develop a genotype score). Eighty-one patients were eligible for the analysis, including 75 (93%) who previously received zidovudine. Thirty-five (43%) were nonresponders. Univariate logistic analysis revealed the following failure-associated mutations: 41L (P = 0.0001), 44D (P = 0.02), 118I (P = 0.0006), 184V (P = 0.04), 210W (P = 0.0004), and 215Y (P = 0.002) for a median stavudine score of 2. Failure was observed in 7 (18.9%) of 37 patients with a score less than 2, compared with 28 (63.6%) of 44 patients with a score of 2 or greater (P < 0.0001). The multivariable analysis showed that the 118I mutation (P = 0.04) was the only independent genotypic predictor of failing on a stavudine- containing highly active antiretroviral therapy.

Background: The genetic barrier, defined as the number of mutations required to overcome drug-selective pressure, is an important factor for the development of HIV drug resistance. Because of high variability between subtypes, particular HIV-1 subtypes could have different genetic barriers for drug resistance substitutions. This study compared the genetic barrier between subtypes using some 2000 HIV-1 sequences (>600 of non-B subtype) isolated from anti-retroviral-naive patients in Europe., Methods: The genetic barrier was calculated as the sum of transitions (scored as 1) and/or transversions (2.5) required for evolution to any major drug resistance substitution. In addition, the number of minor protease substitutions was determined for every subtype., Results: Few dissimilarities were found. An increased genetic barrier was calculated for I82A (subtypes C and G), V108I (subtype G), V118I (subtype G), Q151M (subtypes D and F), L210W (subtypes C, F, G, and CRF02&#95;AG), and P225H (subtype A) (P < 0.001 compared with subtype B). A decreased genetic barrier was found for I82T (subtypes C and G) and V106M (subtype C) (P < 0.001 vs subtype B). Conversely, minor protease substitutions differed extensively between subtypes., Conclusions: Based on the calculated genetic barrier, the rate of drug resistance development may be similar for different HIV-1 subtypes. Because of differences in minor protease substitutions, protease inhibitor resistance could be enhanced in particular subtypes once the relevant major substitutions are selected.

Chronic hepatitis C virus (HCV) is an independent risk factor for antiretroviral-related hepatotoxicity, but little is known about the frequency of severe liver toxicity in patients with HIV-HCV coinfection first treated for HCV (pretreated). The aim of this prospective study of 105 patients was to compare the incidence of progression to severe antiretroviral-related liver toxicity in 66 patients pretreated (36 with interferon-alpha [IFNalpha], 30 with IFNalpha plus ribavirin), and 39 patients not pretreated. The subjects could choose whether to receive anti-HCV therapy. Severe liver toxicity was defined as alanine aminotransferase (ALT) level > or =5-times the upper limit of normal in patients with normal baseline levels and > or =3.5-times in those with increased baseline levels. The authors also estimated the hepatotoxicity-related risk of discontinuing antiretroviral therapy. During antiretroviral therapy, 10 subjects (9.5%) experienced severe hepatotoxicity: 4 of 66 pretreated patients and 6 of 39 untreated patients (24-month survival: 94% +/- 2.9% vs. 85% +/- 5.8%). After adjusting for baseline CD4 cell counts, ALT levels, histologic scores, HCV and HIV viremia, HCV genotype (genotype 1 in 29% of pretreated patients and 20% of patients not pretreated), and previous anti-HCV therapy, the risk of discontinuing anti-HIV treatment was significantly higher in the anti-HCV untreated patients (RR = 10.4; 95% CI: 1.6-66; p =.0127) and in those with increased baseline ALT levels (RR = 1.014; 95% CI: 1.006-1.021; p =.0005). The authors' data suggest that previous treatment of chronic active HCV is an independent factor associated with a decrease of severe liver toxicity as the result of a subsequent antiretroviral regimen. The authors also confirm that the baseline level of ALT is an important prognostic factor for increased liver damage during antiretroviral therapy.

Objective: To evaluate the relation between CD4 and HIV RNA levels at the onset of specific opportunistic infections (OIs) in HIV-infected patients., Design and Methods: The OIs occurring between June 1996 and December 1998 were retrospectively reviewed, considering only the episodes of major and minor OIs in patients with simultaneously available CD4 and plasma HIV RNA determinations before clinical onset who had been untreated or on stable antiretroviral therapy (ART) for at least 2 months., Results: Two hundred seventy-four episodes of different OIs were considered in 216 patients; the median CD4 count was 35 cells/mm3 (range: 0-1154 cells/mm(3)), and the median HIV RNA count was 5.1 log cp/mL (range: < 1.9-6.7 log copies/ml). The different HIV RNA levels were significantly associated with different OIs regardless of CD4 and ART (p < .0001), even when only those occurring in patients with a CD4 count of < or = 50 cells/mm(3) were considered (p = .0049). Kaposi sarcoma, esophageal candidiasis, oropharyngeal candidiasis, and Mycobacterium avium complex disease were associated with significantly above-average median HIV RNA levels, and varicella-zoster virus infection was associated with below-average levels., Conclusions: Different OIs are associated at their onset with significantly different HIV RNA levels, regardless of CD4 cell counts and ART.