A randomized trial was conducted to assess the efficacy of daily (QD) or thrice weekly (TIW) administration of interferon-alpha (IFN) in high doses in combination with ribavirin (1.0-1.2 g/day) in patients with chronic hepatitis C (CHC) who were nonresponders to previous IFN monotherapy. Interferon was administered as 10 MU IFN (QD or TIW) for 4 weeks, followed by 5 MU IFN (QD or TIW) for 20 weeks, and then by 3 MU IFN (QD or TIW) for 24 weeks. Sustained virological response (SVR) was evaluated in 142 patients who received at least one dose of medication. One-fourth of the patients achieved SVR, 26% of those treated with IFN QD and 25% of those treated with IFN TIW (P = 0.85). For genotype 1 patients, SVR rates were 32.4 and 15.8% for IFN QD and IFN TIW, respectively, whereas for genotype non-1 patients the corresponding SVR rates were 20.6 and 36.4%, respectively (test of homogeneity: P = 0.031). This finding was further confirmed by multivariate logistic regression analysis where a statistically significant interaction (P = 0.012) was found between treatment and HCV genotype indicating that the IFN QD regimen was superior to IFN TIW among genotype 1 patients whereas, among genotype non-1 patients, the two treatments were similar (odds ratio of SVR in IFN QD vs IFN TIW: 3.33 among genotype 1 patients, 95% CI: 1.00-11.14). In conclusion, re-treatment of patients not responding to previous IFN monotherapy with a combination of high daily dose of IFN with ribavirin may be beneficial for genotype 1 infected patients.

A randomized trial was conducted to assess the efficacy of interferon-alpha (IFN) daily in combination with ribavirin in 301 naive patients with chronic hepatitis C (CHC). Patients were randomized to receive ribavirin 1.2 g daily (QD) for 48 weeks with either IFN 5 MU (thrice weekly) TIW for 8 weeks followed by IFN 3 MU TIW for 40 weeks (IFN TIW, n = 154) or IFN 5 MU QD for 8 weeks followed by IFN 3 MU QD for 16 weeks followed by IFN 3 MU TIW for 24 weeks (IFN QD, n = 147). Treatment discontinuation rates, because of adverse events, were similar in the two arms (14.9% in IFN TIW and 14.3% in IFN QD, P = 0.87). The proportion of patients with sustained virological response (SVR) was 27.9% for patients treated TIW and 38.8% for those treated QD (P = 0.046). According to logistic regression analysis, patients in the IFN QD arm had 1.7 times higher probability of achieving SVR, than those receiving IFN TIW (P = 0.038). Low baseline viral load (P = 0.017) and genotype non-1 (P = 0.036) were associated with higher SVR rates. Combination of IFN/ribavirin for 48 weeks is more effective when IFN is administered daily for the first 24 weeks in naive patients with CHC.

Recombination plays a pivotal role in the evolutionary process of many different virus species, including retroviruses. Analysis of all human immunodeficiency virus type 1 (HIV-1) intersubtype recombinants revealed that they are more complex than described initially. Recombination frequency is higher within certain genomic regions, such as partial reverse transcriptase (RT), vif/vpr, the first exons of tat/rev, vpu and gp41. A direct correlation was observed between recombination frequency and sequence similarity across the HIV-1 genome, indicating that sufficient sequence similarity is required upstream of the recombination breakpoint. This finding suggests that recombination in vivo may occur preferentially during reverse transcription through the strand displacement-assimilation model rather than the copy-choice model.

The current case study provided an unusual setting to track the evolution of HIV-1 envelope gene over a maximum period of 6 years in two asymptomatic spouses undergoing suppressive highly active antiretroviral therapy. For this purpose, proviral DNA samples taken from uncultured peripheral blood mononuclear cells and spanning the C2-V5 regions of env were analyzed at three sampling points per subject. Two distinct topological patterns were observed in the phylogenetic reconstructions of the genetically linked sequences of the couple: an intermingled pattern and a sequentially shifting pattern in the virus populations of the male index case and his spouse, respectively. Application of three evolutionary models for the amino acid-encoded sites, using the maximum likelihood approach, indicated the operation of positive selection in the region only at the second time point in the woman, before receiving therapy. These findings reinforce the evidence of a crucial role for host-selective constraints on HIV-1 env evolution in vivo.