Time of initiation of antiretroviral therapy: impact on HIV-1 viraemia. The Swiss HIV Cohort Study

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.

HIV chemotherapy

The use of chemotherapy to suppress replication of the human immunodeficiency virus (HIV) has transformed the face of AIDS in the developed world. Pronounced reductions in illness and death have been achieved and healthcare utilization has diminished. HIV therapy has also provided many new insights into the pathogenesis and the viral and cellular dynamics of HIV infection. But challenges remain. Treatment does not suppress HIV replication in all patients, and the emergence of drug-resistant virus hinders subsequent treatment. Chronic therapy can also result in toxicity. These challenges prompt the search for new drugs and new therapeutic strategies to control chronic viral replication.

Concentrations of human immunodeficiency virus type 1 (HIV-1) RNA in cerebrospinal fluid after antiretroviral treatment initiated during primary HIV-1 infection

In 6 patients with primary human immunodeficiency virus type 1 (HIV-1) infection, concentrations of HIV-1 RNA and beta(2)-microglobulin were monitored in cerebrospinal fluid (CSF) and in plasma during antiretroviral therapy. Four patients had neurological symptoms. At baseline, the CSF of 5 patients had detectable levels of HIV-1 RNA (median, 3.68 log(10) copies/mL; range, <2.60-5.67 log(10) copies/mL), and the CSF of 3 patients had elevated levels of beta(2)-microglobulin. After 8 weeks of treatment, the median concentrations of HIV-1 RNA in CSF had decreased to <2.60 log(10) copies/mL (range, <1.60-3.00 log(10) copies/mL; P=.04) and in plasma to 3.07 log(10) copies/mL (range, 2.57-3.79 log(10) copies/mL; P=.03). Median concentration of beta(2)-microglobulin in CSF had decreased to 1.2 mg/L (range, 0.9-1.7 mg/L; P=.06) and, in plasma, to 1.7 mg/L (range, 1.1-2.2 mg/L; P=.03). After 48 weeks, HIV-1 RNA concentrations in 1 patient were still 1.97 log(10) copies/mL in CSF and 1.51 log(10) copies/mL in plasma, although beta(2)-microglobulin concentrations in CSF and plasma had normalized after 8 weeks.

Decay of cell-associated HIV-1 DNA correlates with residual replication in patients treated during acute HIV-1 infection

OBJECTIVES

To evaluate the decay rate of cell-associated HIV-1 RNA and DNA and to identify factors associated with residual viral load in patients treated at the time of primary HIV-1 infection.

PATIENTS

A group of 15 patients adherent to highly active antiretroviral therapy (HAART) with sustained undetectable HIV-1 viremia for at least 24 months.

METHODS

Viremia, cell-associated HIV-1 RNA and DNA in blood and lymph node mononuclear cells were measured using ultrasensitive assays.

RESULTS

Viremia decreased rapidly in all patients; HIV RNA remained < 3 copies/ml in nine patients and fluctuated between 3 and 50 copies/ml in five patients and between 50 and 200 copies/ml in one patient. Decay rates of cell-associated RNA and DNA presented an inflexion point at 1 and 3 months, respectively: first-phase mean half-lives were 0.15 and 0.84 months, respectively, and second-phase mean half-lives were 13.7 and 6.6 months, respectively (95% confidence interval 4.4-13.8). The second phase decay rates were markedly slower, with a DNA decay rate that was highly associated with the mean levels of cell-associated RNA measured in blood from 6 to 33 months (P= 0.001) and in lymph nodes collected at 14 months (P= 0.02).

CONCLUSIONS

The clearance of HIV-1 infected cells is correlated with the extent of viral replication as measured by cell-associated RNA levels in both blood and lymph nodes. Quantification of cell-associated RNA and DNA further defines treatment efficacy in 'aviremic' patients.

Effects of mycophenolic acid on human immunodeficiency virus infection in vitro and in vivo

Mycophenolic acid, a selective inhibitor of the de novo synthesis of guanosine nucleotides in T and B lymphocytes, has been proposed to inhibit human immunodeficiency virus (HIV) replication in vitro by depleting the substrate (guanosine nucleotides) for reverse transcriptase. Here we show that mycophenolic acid induced apoptosis and cell death in a large proportion of activated CD4+ T cells, thus indicating that it may inhibit HIV infection in vitro by both virological mechanisms and immunological mechanisms (depletion of the pool of activated CD4+ T lymphocytes). Administration of mycophenolate mophetil, the ester derivate of mycophenolic acid, to HIV-infected subjects treated with anti-retroviral therapy and with undetectable viremia resulted in the reduction of the number of dividing CD4 + and CD8+ T cells and in the inhibition of virus isolation from purified CD4+ T-cell populations. Based on these results, the potential use of mycophenolate mophetil in the treatment of HIV infection deserves further investigation in controlled clinical trials.