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Effective treatment of infections with human immunodeficiency virus type 1 (HIV-1) may require a combination of antiviral drugs that act by different mechanisms. We report that the combination of 2',3'-dideoxycytidine (ddCyd) and recombinant interferon-alpha-A (rIFN-alpha-A) acts synergistically against HIV-1 replication in vitro. Various cell types (peripheral blood leukocytes, a CD4-positive T cell line, and two monocyte-macrophage lines) have been studied. For each set of dose-effect data, the degree of drug interaction was quantitatively assessed with the median-effect principle and the isobologram equation by using a computer analysis. Under various culture conditions using several concentrations of drugs, multiplicities of infectious virus, and assay systems, antiviral synergism was consistently observed against HIV-1 replication without enhanced cell toxicity. Synergism was seen at concentrations as low as 0.02 microM ddCyd plus 4 U of rIFN-alpha-A/mL or 0.01 microM ddCyd plus 8 U of rIFN-alpha-A/mL, whereas 10-fold higher concentrations were usually required to achieve similar effects with single drugs.

Human immunodeficiency virus (HIV), the etiological agent of the acquired immunodeficiency syndrome (AIDS), was treated with either Betadine (povidone-iodine) Solution or Betadine Surgical Scrub. HIV inactivation was analyzed using the viral reverse transcriptase assay or by observing the cytopathic effect produced in HIV-infected, H-9, T-cell cultures. The minimum effective Betadine dose was 0.25% for complete inactivation of HIV that was treated for various time intervals (immediate vortex to ten minutes). The titer of HIV stocks used in these experiments (10(5) TCID50 per mL) was greater than amounts generally detected in clinical specimens. Our results provide a rationale for the use of povidone-iodine as a topical antiseptic against HIV in the clinic or laboratory.

The detection of human immunodeficiency virus (HIV)-associated antigens was simplified by the application of dot immunobinding on a nitrocellulose matrix. Antigens were detected by applying the polyethylene glycol-precipitated supernatants of experimentally infected cultures directly onto nitrocellulose strips and sequentially incubating the strips with an anti-HIV antiserum and an alkaline phosphatase-conjugated, species-specific antiserum. The immune reaction was developed by adding the precipitable substrate indoyl phosphate. The dot immunobinding assay was nearly as sensitive as the reverse transcriptase assay in detecting HIV antigens in experimentally infected peripheral blood mononuclear cells, as well as in a T-cell line. The technique was also useful in the in vitro evaluation of antiviral agents. The dot immunobinding assay is a simple and sensitive technique that is useful in the detection of HIV antigens in studies of viral pathogenesis.

Virus-specific cytotoxic T lymphocytes (CTL) which kill virus-infected cells are thought to be a major host defence against viral infections. Here we report the existence of human immunodeficiency virus (HIV)-specific CTL in persons infected with this virus, the aetiological agent of AIDS (acquired immunodeficiency syndrome). Recombinant HIV-vaccinia viruses were used to express HIV antigens in B-cell lines established from subjects seropositive for HIV and seronegative controls. Circulating lymphocytes capable of killing HIV env-expressing autologous B cells were detected in eight of eight seropositive subjects; in addition, at least three seropositive subjects demonstrated gag-specific cytotoxic responses. No HIV-specific cytotoxicity was observed in seronegative subjects. Selective inhibition of the env-specific cytotoxicity by a CD3-specific monoclonal antibody indicates that the effectors are T cells. This demonstration of a cytotoxic T-cell immune response to HIV in infected individuals should prove useful in investigating the immunopathogenesis of HIV infection further and in evaluating AIDS vaccine strategies.

A gene encoding a 113-amino acid, NH2-terminal fragment of CD4, rsT4.113, was constructed and expressed in Escherichia coli under the control of the tryptophan operon promoter. Following induction, rsT4.113 is produced at 5-10% of total E. coli protein, and it is found in inclusion bodies. The protein is purified in two steps under denaturing and reducing conditions. Solubilized rsT4.113 is first purified on a column of Q-Sepharose to remove low molecular weight contaminants and then purified to greater than 95% homogeneity by gel filtration. Renaturation of rsT4.113 is achieved at approximately 20% yield by dilution and dialysis. High performance liquid chromatography analysis of renatured rsT4.113 reveals a less than 15% contaminant of reduced protein. Purified and renatured rsT4.113 contains epitopes for both OKT4a and Leu3a, anti-CD4 monoclonal antibodies which block CD4-gp 120 association, but lacks measurable affinity toward a nonblocking anti-CD4 monoclonal antibody, OKT4. By comparison to a longer form (375 amino acids) of recombinant soluble T4 produced in mammalian cells that contains the entire extracellular domain, rsT4.113 has a comparable affinity for binding to OKT4a and Leu3a in a radioimmunoassay. Analysis of antiviral activity of rsT4.113 demonstrates that the E. coli-derived protein inhibits human immunodeficiency virus-induced syncytium formation with an IC50 of 5-10 micrograms/ml. These data demonstrate that the human immunodeficiency virus-binding domain of CD4 is localized within the NH2-terminal 113 amino acids of CD4 and is contained within a structure homologous to the kappa variable-like domain of immunoglobulins.

Azidothymidine and ribavirin both inhibit replication of human immunodeficiency virus in vitro and show promise of clinical utility in patients infected with this virus. In this study, the possible interactions of these drugs were examined in vitro, and a reproducible antagonism between azidothymidine and ribavirin was found to occur under a variety of experimental conditions. The mechanism responsible for this antagonism appeared to be inhibition of azidothymidine phosphorylation by ribavirin. Because similar effects may occur in vivo, clinical trials of these two drugs in combination must be performed only under carefully controlled conditions.

Characterization of the host immune response to human immunodeficiency virus type 1 (HIV-1) is critical to the rational design of an effective AIDS vaccine. In this study, cytotoxic T lymphocytes (CTL) specific for HIV-1 reverse transcriptase (RNA-dependent DNA polymerase) were found in blood samples from HIV-1-infected individuals. CTL targets were prepared by immortalizing B cells from ten seropositive and six seronegative individuals, and then infecting these cells with recombinant vaccinia viruses containing HIV-1 genes. CTL directed against autologous B lymphoblasts expressing HIV-1 reverse transcriptase were detected in fresh blood samples from eight HIV-1 seropositive subjects, but in no seronegative controls. The effector cells were identified as major histocompatibility complex-restricted CD3+CD8+ lymphocytes. Because the HIV-1 pol gene is highly conserved among different isolates and generates both humoral and cellular immune responses, it bears consideration for inclusion in a candidate AIDS vaccine.

The T-cell surface glycoprotein, CD4 (T4), acts as the cellular receptor for human immunodeficiency virus, type 1 (HIV-1), the first member of the family of viruses that cause acquired immunodeficiency syndrome. HIV recognition of CD4 is probably mediated through the virus envelope glycoprotein (gp120) as shown by co-immunoprecipitation of CD4 and gp120 (ref.5) and by experiments using recombinant gp120 as a binding probe. Here we demonstrate that recombinant soluble CD4(rsT4) purified from the conditioned medium of a stably transfected Chinese hamster ovary cell line is a potent inhibitor of both virus replication and virus-induced cell fusion (syncytium formation). These results suggest that rsT4 is sufficient to bind HIV, and that it represents a potential anti-viral therapy for HIV infection.

Both recombinant alpha A interferon and azidothymidine inhibit the replication of human immunodeficiency virus in peripheral blood mononuclear cells. Combinations of recombinant alpha A interferon and azidothymidine at concentrations that are easily achievable in patients synergistically inhibit human immunodeficiency virus in vitro with minimal toxicity. Combinations of antiretroviral compounds that act by different mechanisms may prove useful in the treatment of acquired immunodeficiency syndrome-related disorders.

The antiviral activities of various interferon preparations against human immunodeficiency virus (HIV) were evaluated in vitro. Recombinant interferon alpha-A, and beta interferons and leukocyte-derived alpha interferons show similar concentration-dependent antiviral activity. Recombinant and lymphocyte-derived gamma interferons show minimal antiviral activity against HIV replication in normal peripheral blood mononuclear cells, but definite activity against HIV in the H9 lymphocytic and U937 monocyte-macrophage cell lines.

Human immunodeficiency virus (HIV) elicits the production of virus-specific antibodies in infected individuals. We investigated the ability of serum from HIV-infected individuals to mediate antibody-dependent cellular cytotoxicity in an in vitro 51Cr release assay system. Fresh peripheral blood mononuclear cells from healthy donors seronegative for HIV were used as cellular effectors against HIV-infected and uninfected H9 target cells in the presence of serum from HIV-infected or uninfected donors. Serum from HIV-infected, but not uninfected, donors significantly augmented cytolysis of virus-infected targets (P less than .005). There was no augmented killing of uninfected H9 cells with sera from either group. Studies using serum from mice that had been immunized with synthetic peptides from the HIV envelope region suggested that this response is directed, at least in part, at several determinants of the transmembrane portion of the HIV envelope glycoprotein.

Serum neutralizing antibodies against the human immunodeficiency virus were frequently detected in infected individuals, and low or absent serum neutralizing titers correlated with poor prognosis. Multiple diverse human immunodeficiency virus isolates were found to exhibit similar susceptibility to neutralization by a panel of human seropositive sera, suggesting that neutralizing antibodies are largely directed against conserved viral domains. Furthermore, utilizing antisera raised against a library of synthetic env peptides, four regions which are important in the neutralization process have been identified within both human immunodeficiency virus envelope glycoproteins (gp41 and gp120). Three of these are in conserved domains and should be considered for inclusion in a candidate vaccine.

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.

Human immunodeficiency virus (HIV) has been isolated from both male and female genital secretions. We evaluated the pattern of female genital carriage during the menstrual cycle, and its relationship to HIV viremia. Seven menstruating seropositive women and one seronegative control had cervical secretions and venous blood samples cultured at weekly intervals during a single menstrual cycle. The virus was isolated from cervical secretions in four of seven women. No specific cycle pattern was seen, and positivity for HIV at one site (blood or cervical) did not correlate with positivity at another site. Blood cultures generally, but not always, became positive earlier than cultures from cervical specimens, suggesting higher titers of virus in blood. Thus, HIV secretion may be intermittent. These findings, together with earlier reports, suggest that seropositive women may transmit HIV at any time during the menstrual cycle.