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Combinations of the human immunodeficiency virus (HIV) Tat protein antagonist Ro 24-7429 with either the HIV protease inhibitor Ro 31-8959 or the HIV reverse transcriptase inhibitors AZT (3'-azido-3'-deoxythymidine), ddC (2',3'-dideoxycytidine), ddI (2',3'-dideoxyinosine), and nevirapine were synergistic or additive in reducing HIV type 1 p24 antigen production in CEM cells or inhibiting HIV type 1-induced syncytium formation in HT4-6C cells.

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We examined the kinetic interaction of purified recombinant DNA-derived human immunodeficiency virus type 1 (HIV-1) reverse transcriptase with R82150, a member of the tetrahydroimidazo[4,5,1-jk]-[1,4]-benzodiazepin-2(1H)-thione family of compounds (Pauwels, R., Andries, K., Desmyter, J., Schols, D., Kukla, M.J., Breslin, H.J., Raeymaeckers, A., Van Gelder, J., Woestenborghs, R., Heykants, J., Schellekens, K., Janssen, M.A.C., De Clercq, E., and Janssen, P.A.J. (1990) Nature 343, 470-474). R82150 inhibited noncompetitively the utilization of homopolymeric and heteropolymeric template-primers (KI range 280-300 nM). Inhibition of dNTP substrate incorporation was also noncompetitive (KI range 100-890 nM). In contrast, 100 microM R82150 did not inhibit human DNA polymerases alpha, beta, or gamma. Gel electrophoresis was used to analyze the effect of inhibitors on extension of heteropolymeric template-primers by HIV-1 reverse transcriptase. ddCTP induced accumulation of partially extended primers which had been terminated at sites requiring incorporation of deoxycytidylate. Competing template-primers reduced accumulation of both fully and partially extended primers. In contrast, R82150 induced accumulation of shortened primers that were terminated at various sites that did not correspond to any one particular deoxynucleotide species. Our results suggest that R82150 does not interact with HIV-1 reverse transcriptase as an analog of either template-primer or deoxynucleoside triphosphate substrate, but may bind allosterically at a site unique to this replicase.

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The hydroxy metabolites of rimantadine (3-5) were synthesized and compared to amantadine (1) and rimantadine (2) for their ability to inhibit the replication of influenza viruses in vitro. All three metabolites were inhibitory to wild-type influenza A viruses (H3N2 and H1N1). In particular, 2-hydroxyrimantadine (3) showed similar activity to amantadine, but the 3- and 4-hydroxy metabolites (4 and 5, respectively), both of which are found in rimantadine-treated patients, showed only modest inhibitory activity. A rimantadine-resistant isolate of influenza A virus exhibited cross-resistance to amantadine and to each of the metabolites 3-5. None of the compounds were effective against influenza B virus.

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The nucleoside analog acyclovir [9-(2-hydroxyethoxymethyl)guanine] and the hybrid recombinant human alpha interferon (rHuIFN-alpha A/D) were evaluated in weanling mice for their efficacy alone and in combination against a lethal systemic infection with herpes simplex virus type 1. Simultaneous parenteral treatment with combinations of both agents at various doses resulted in a higher percentage of survival than when either agent was administered alone, with a synergistic interaction demonstrated at certain dose combinations. Sequential administration of parenteral rHuIFN-alpha A/D and oral acyclovir, administered by gavage or supplied ad libitum in drinking water, resulted in a synergistic interaction at all dose combinations tested. These results suggest that combinations of interferon and acyclovir may be useful in treating primary herpes simplex virus infections in humans.

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Hairless mice were infected intracutaneously with HSV-1 and treated with rHuIFN-alpha A/D, a recombinant DNA-derived hybrid human interferon-alpha that is active on mouse cells in vitro and in vivo. When given alone (1 or 2 X 10(5) units/dose) at times soon after infection, interferon showed some efficacy, reducing disease severity by 20-30% compared to control. Oral acyclovir was also effective in reducing disease severity in a dose-dependent manner, even when treatment was begun 72 h post-infection after herpetic vesicles had become apparent. When used in combination with acyclovir (400 mg/kg/day beginning 72 h post-infection), rHuIFN-alpha A/D (beginning 4 h post-infection) greatly enhanced the therapeutic effect of the nucleoside, giving a 64% reduction in disease severity score relative to control (compared to 14% for acyclovir alone). Furthermore, although interferon treatment alone was ineffective if begun after disease was apparent, it nonetheless potentiated the activity of acyclovir when co-administered with the nucleoside beginning 72 h post-infection. Combination therapy markedly reduced disease severity, limited the progression of the infection to the vesicular stage in 50% of recipient mice and promoted a more rapid onset of healing than was obtained by treatment with acyclovir alone.

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During the course of clinical investigation of partly purified human leucocyte interferon (IFN) prepared at the Finnish Red Cross (PIF), neutralising IgG antibodies to human leucocyte IFN were detected in the sera of 3 patients with cancer. In 2 of these patients, the antibodies were detected in serum before treatment with PIF. In the third patient antibodies developed during the course of treatment. Antibody titres against six recombinant human leucocyte IFN sub-types and one recombinant hybrid human leucocyte IFN were different in the 3 patients.

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The structural proteins of an arenavirus pathogen, Machupo virus, were compared to the structural proteins of two previously characterized non-pathogenic arenaviruses, Pichinde and Tacaribe, in SDS-polyacrylamide gels. Similarities in mol. wt. of the major structural proteins from both pathogenic and non-pathogenic viruses were apparent; however, some differences in the number of glycosylation properties of minor proteins were observed. Machupo virions contain two major protein species. The most prominent is a non-glycosylated protein with a mol. wt. of 68000, while the other was glycosylated protein with a mol. wt. of 41000. Minor amounts of other proteins (mol. wt. 84000, 74000, 50000 and 15000) and a glycolipid were also observed.

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Liter volumes of a human arenavirus pathogen (Machupo) and a nonpathogen (Tacaribe) were concentrated 30 to 100 times in less than 90 min without significant loss of particle infectivity.

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