Effects of Early Antiretroviral Treatment on HIV-1 RNA in Blood and Lymphoid Tissue: A Randomized Trial of Double Versus Triple Therapy:

Persistence of lamivudine-sensitive HIV-1 quasispecies in the presence of lamivudine in vitro and in vivo

The establishment of persistent infection is one of the major obstacles facing the eradication of HIV-1. To improve our understanding of the mechanisms of viral persistence, we investigated the fate of defined viral quasispecies under conditions that might favor their eradication. We retrospectively analyzed changes in viral populations in HIV-1-infected patients treated with zidovudine/lamivudine and subsequently failing therapy within months in the years 1996 to 1997. Furthermore, we developed an in vitro model based on simultaneous infection of T cells with 2 or more different viral variants. Changes in minority quasispecies of drug-sensitive and drug-resistant HIV-1 variants based on lamivudine and the corresponding lamivudine-resistant viruses carrying the M184I or M184V mutation were investigated using an allele-specific real-time polymerase chain reaction assay. We demonstrate that lamivudine-sensitive and lamivudine-resistant HIV-1 variants are able to persist despite highly unfavorable conditions in vivo and in vitro and that selective advantages of viral variants can vary depending on the complexity of other simultaneously replicating viral variants.

Glancing behind virus load variation in HIV-1 infection

Although the steady-state virus load during HIV-1 infection is remarkably stable within a patient, it displays variation over several orders of magnitude between patients. Despite intensive research, the host and virus factors that are responsible for the observed variation remain poorly understood. Comparison of model predictions with clinical data suggests that most of the variation in steady-state virus load between patients reflects variation of the net rate at which activated CD4 cells are produced.

Socioeconomic status, access to triple therapy, and survival from HIV-disease since 1996

BACKGROUND

In the era before highly active antiretroviral therapy (HAART), socioeconomic status was associated with survival from HIV disease. We have explored socioeconomic status, access to triple therapy (HAART), and mortality in the context of a universal healthcare system.

METHODS

We evaluated 1408 individuals who initiated double or triple therapy between 1 August 1996 and 31 December 1999, and were followed until 31 March 2000. Cumulative HIV-related mortality rates were estimated using Kaplan-Meier methods and Cox proportional hazards regression.

RESULTS

In the overall Cox model, we found that adherence [risk ratio (RR) 0.83; per 10% increase], CD4 cell count (RR 1.53; per 100 cell decrease), and lower socioeconomic status (RR 2.19; high versus low), were associated with HIV-related mortality. However, socioeconomic status was not significant among patients prescribed triple therapy in a stratified analysis, or in a sub-analysis restricted to patients prescribed HAART in the initial regimen. When we investigated if inequitable access to HAART by socio-economic status could explain the discrepancy, we found that persons in the lower socio-economic strata were less likely to be prescribed triple therapy even after adjustment for clinical characteristics.

CONCLUSION

In a universal healthcare system, socioeconomic status was strongly associated with HIV-related mortality. When we investigated possible explanations for this association, we found that individuals of lower socioeconomic status were less likely to receive triple therapy after adjustment for clinical characteristics. Our findings highlight the need for the monitoring of therapeutic guidelines to ensure equitable access, as treatment strategies are updated.

Clinical efficacy of early initiation of HAART in patients with asymptomatic HIV infection and CD4 cell count > 350 x 10(6) /l

OBJECTIVE

To evaluate the efficacy of early initiation of highly active antiretroviral therapy (HAART), we compared the clinical course of two nested, matched cohorts within the Swiss HIV Cohort Study.

METHODS

We selected all asymptomatic patients who started HAART between 1 January 1996 and 31 December 1999 with a CD4 cell count > 350 x 10(6)/l. We then matched them with asymptomatic participants who were seen at around the same time and who remained untreated during the following 12 months. This control group was further matched for age, sex, CD4 cell count, viral load, and HIV risk category, generating 283 pairs of treated versus untreated patients.

RESULTS

During observation of median 3.19 versus 2.66 years, CDC stage B/C occurred in 6.4% versus 21.2%, AIDS in 1.8% versus 5.3%, death in 2.1% versus 6.4%, and AIDS or death of 'natural' causes in 2.8% versus 6.7% of the treated versus untreated patients. In multivariable Cox regression analysis, treatment reduced the risk of clinical progression by a factor of four- to five fold. During follow-up, the treated group had significantly higher CD4 counts and lower HIV-1 RNA levels. Intolerance/adverse events led to change or stop of at least one drug in 35% of treated patients. The entire regimen was interrupted at least once by 41% of patients, and 24% had no treatment anymore at the end of follow-up.

CONCLUSIONS

The initiation of HAART in asymptomatic patients with CD4 cell count > 350 x 10(6)/l significantly delayed clinical progression. However, the risk of severe clinical events with deferred therapy was low and must be counter balanced against the burden and toxicity of HAART.

Combined effect of zidovudine (ZDV), lamivudine (3TC) and abacavir (ABC) antiretroviral therapy in suppressing in vitro FIV replication

In view of close similarities at the molecular and clinical levels, feline immunodeficiency virus (FIV) infection of the domestic cat is subject of increasing attention as an animal model for human immunodeficiency virus (HIV) infection. A range of reverse transcriptase inhibitors effective against HIV are also active against FIV, allowing successful use of the cat model to investigate drug interactions and resistance development. Nevertheless, while combined nucleoside analog and protease inhibitor usage has proven remarkably effective in treating HIV infection, combination antiretroviral therapy of FIV infection has been hampered by lack of protease inhibitors specific for FIV. In an attempt to circumvent this problem, we have examined the feasibility of applying in the FIV system combination protocols lacking a protease inhibitor. We now report that, as observed during HIV infection, the nucleoside analog abacavir (ABC or 1592U89) is able to effectively block in vitro FIV-replication. Furthermore, we demonstrate that combined usage of ABC with the nucleoside analogs zidovudine (ZDV or AZT) and lamivudine (3TC) also blocks in vitro FIV replication in a synergistic manner. However, in contrast to its effect on HIV replication, the ribonucleotide reductase inhibitor hydroxyurea (HU) is unable to effectively control in vitro FIV replication.

Treatment-induced decline of human immunodeficiency virus-1 p24 and HIV-1 RNA in lymphoid tissue of patients with early human immunodeficiency virus-1 infection

We report detailed quantitative analysis of human immunodeficiency virus-1 (HIV-1) p24 and HIV-1 RNA in tonsil biopsies from 13 patients with early, asymptomatic HIV infection before and during combination antiretroviral therapy. Using fluorescent microscopy in conjunction with reverse transcriptase-polymerase chain reaction of frozen tissue sections, we show that plasma and tissue viral loads decreased by approximately 3 logs during the 1-year treatment period, with good correlation between the HIV-1 p24 and HIV-1 RNA response in tissue. The decrease of tissue viral load was delayed compared to plasma viral load, possibly explained by the observation that the amount of follicular dendritic cell-associated virus correlated best with the area under the curve of plasma HIV-1 RNA throughout the last 12 weeks. Before and during treatment, the relative proportions of HIV-1 on follicular dendritic cells and within mononuclear cells remained constant, suggesting similar decay characteristics in these two lymphoid tissue compartments. However, viral p24 or RNA remained almost always detectable in tissue despite full suppression of HIV-1 RNA in plasma, and increased even after short-term rebounds in plasma viral load. Thus, full and sustained suppression of viral replication was required to efficiently decrease viral load in lymphoid tissue, but complete abolition of residual viral replication was not achieved.