Two-drug combinations of zidovudine, didanosine, and recombinant interferon-alpha A inhibit replication of zidovudine-resistant human immunodeficiency virus type 1 synergistically in vitro.

Optimal management of human immunodeficiency virus type 1 (HIV-1) infections may require combinations of anti-HIV-1 agents. Zidovudine (AZT, 3'-azido-3'-deoxythymidine), didanosine (ddI, 2',3'-dideoxyinosine), and recombinant interferon-alpha A (rIFN-alpha A) were evaluated in two-drug regimens against replication of AZT-resistant HIV-1 in vitro. AZT-sensitive and AZT-resistant isolate pairs derived from two individuals before and after extended AZT monotherapy were studied. Drug interactions using peripheral blood mononuclear cells infected with HIV-1 were evaluated mathematically. Synergistic interactions were seen among AZT, ddI, and rIFN-alpha A in two-drug regimens against AZT-resistant HIV-1 in vitro, even when AZT was included in the treatment regimen. Mixtures of wild-type and mutant reverse transcriptase genes were found in one of the late-AZT therapy isolates, suggesting that the mechanism of synergy of AZT-containing regimens may involve inhibition of AZT-sensitive viruses in the viral pool. These studies suggest that AZT may be useful in drug combination regimens, even when AZT-resistant viruses are isolated in vitro.

Recombinant soluble CD4 therapy in patients with the acquired immunodeficiency syndrome (AIDS) and AIDS-related complex. A phase I-II escalating dosage trial.

STUDY OBJECTIVE: To study the safety and pharmacokinetics and to derive preliminary evidence on surrogate indicators of efficacy of recombinant soluble CD4 (rsCD4) in patients with the acquired immunodeficiency syndrome (AIDS) and advanced AIDS-related complex. DESIGN: Open label, escalating dosage, phase I-II tolerance trial. SETTING: Massachusetts General Hospital, Cedars-Sinai Medical Center, and Stanford University Medical School, three tertiary care institutions and members of the National Institute of Allergy and Infectious Diseases AIDS Clinical Trials Group. INSTRUCTIONS: Cohorts of 3 to 11 patients received rsCD4 by intravenous infusion or intramuscular injection in dosages of up to 30 mg per day for 28 days. MEASUREMENTS AND MAIN RESULTS: Recombinant soluble CD4 was tolerated by these patients with no significant clinical or immunologic toxicities. Serum levels of rsCD4 in patients receiving doses of 9 or 30 mg per day administered intramuscularly were in the range of rsCD4 concentrations required to inhibit replication of human immunodeficiency virus 1 (HIV-1) in vitro. A decline in serum HIV-1 p24 antigen was seen in patients receiving 30 mg of rsCD4 daily, but no such changes were noted at lower dosages. CONCLUSIONS: Recombinant soluble CD4 is well tolerated by patients with AIDS or advanced AIDS-related complex. Our study has also provided preliminary evidence of antiviral activity of rsCD4 in vivo. Our data suggest that further trials of receptor-based therapies against HIV-1 are warranted.

Effects of human immunodeficiency virus (HIV) on the cytotoxic response to Epstein Barr virus (EBV) transformed B lymphocytes.

The human immunodeficiency virus (HIV) may interact with the Epstein Barr virus (EBV) indirectly by effects on the T4 lymphocyte or directly by effects on EBV transformed B lymphocytes. We have confirmed the susceptibility of EBV transformed B lymphocytes to productive HIV infection, and have evaluated the cytotoxic activity of HIV seronegative and seropositive donors after sensitization by their autologous EBV infected (monoinfected) or EBV and HIV infected (coinfected) transformed cell lines in a 51Cr release cytotoxicity assay. When sensitized by the coinfected cell line and assayed against monoinfected and coinfected cell lines, the cytotoxic activity of the seronegative donors was inhibited when compared to the cytotoxic effectors sensitized by the monoinfected B cell line. The inhibition appeared to be unrelated to direct HIV infection of the T4 effector cells and was reversible by addition of recombinant interleukin-2. Although deficient in their EBV cytotoxic activity in comparison to the seronegative donors, the HIV seropositive donors lysed the coinfected cell line better than the monoinfected cell line, whether or not HIV superinfected cells were used during the sensitization phase. In HIV seronegative donors, HIV may inhibit the immune response to EBV transformed B lymphocytes. This inhibition is not observed in HIV seropositive donors. These studies suggest the development of cytolytic effector mechanisms directed at HIV infected cells during HIV infection.

Detection of human T-cell lymphotropic virus type III-related antigens and anti-human T-cell lymphotropic virus type III antibodies by anticomplementary immunofluorescence.

Techniques presently available for detection of human T-cell lymphotropic virus type III (HTLV-III) antigens and antibodies are laborious or relatively nonsensitive. We adapted anticomplementary immunofluorescence (ACIF) for these purposes. In HTLV-III-infected cells, specific ACIF was demonstrated by a diffuse speckling pattern that often resulted in a peripheral cellular rim of fluorescence. A 97% concordance was demonstrated between the ACIF assay and other sensitive tests for HTLV-III antibody detection (Western blot and membrane immunofluorescence and fixed-cell immunofluorescence tests). The ACIF assay was both more sensitive and more specific when compared with the enzyme-linked immunosorbent assay. For detection of HTLV-III antigens, the ACIF assay appeared to be as sensitive as the reverse transcriptase assay and more sensitive, with less background reactivity, than the conventional immunofluorescence assay. The ACIF assay often detected low levels of HTLV-III antigens within 3 days of infection in vitro, compared with 5 to 7 days with the indirect immunofluorescence assay, and generally paralleled the reverse transcriptase assay. The ACIF assay is a simple, sensitive, and specific assay for detection of HTLV-III-related antigens and antibodies. It should prove useful in the diagnosis of HTLV-III infection, as well as in studies of pathogenesis.

Inhibition of human T-cell lymphotropic virus type III in vitro by phosphonoformate.

Phosphonoformate, an inhibitor of reverse transcriptase in a number of retroviruses, was shown to have a dose-related inhibitory effect on human T-cell lymphotropic virus type III (HTLV-III) replication in the H9 cell line in vitro. HTLV-III replication was eliminated at a concentration of 680 mumol, a non-cytotoxic dose. A lower dose of 132 mumol inhibited HTLV-III replication by more than 98%, as measured by reverse transcriptase activity, compared with untreated infected cultures. Reverse transcriptase activity in HTLV-III particles was completely inhibited by 5.0 mumol phosphonoformate.

PIP: Phosphonoformate, an inhibitor of reverse transcriptase in a number of retroviruses, was shown to have a dose-related inhibitory effect on human T-cell lymphotropic virus type III (HTLV-III) replication in the H9 cell line in vitro. HTLV-III replication was eliminated at a concentration of 680 mcgmol, a noncytotoxic dose. A lower dose of 132 mcgmol inhibited HTLV-III replication by more than 98%, as measured by reverse transcriptase activity, compared with untreated infected cultures. Reverse transcriptase activity in HTLV-III particles was completely inhibited by 5 mcgmol of phosphonoformate. Growth of uninfected H9 cells was not affected by the concentration of the drug. In clinical trials to treat cytomegalovirus infection in immunocompromised patients, constant serum levels of between 100-450 mcgmol of phosphonoformate have been achieved in 140 subjects. Further studies are recommended to evaluate the potential of phosphonoformate in patients infected with HTLV-III. It may be the least toxic of the antiviral agents that have been shown to have anti-HTLV-III activity.