Properties of an RNA polymerase complex detected in influenza virus-infected cells

Antagonism of interferon induction in spleen and adherent peritoneal cells of mice by the lipophilic antiviral muramyl peptide MTP-PE

The immunomodulator muramyl tripeptide-phosphatidylethanolamine (MTP-PE) has been shown to enhance host resistance against a variety of experimental infections and to cure influenza virus infection in mice when given in a single dose, even at a late stage of the disease. Tests of its capacity to induce alpha/beta- and gamma-interferon (IFN-alpha/beta and -gamma) in vitro demonstrated that it is neither an inducer nor a primer of IFN synthesis. On the contrary, we found that it inhibits the induction of IFN-alpha/beta and -gamma by poly(rI:rC), Newcastle disease virus, lipopolysaccharide, or concanavalin A in adherent cells from the peritoneal cavity and spleen of mice. The antiviral activity of already induced or exogenously added murine IFN was, however, not impaired.

Intracellular glycosylation of influenza hemagglutinin: the effect of glucosamine

The intracellular glycosylation of influenza virus hemagglutinin has been studied in calf kidney primary cultures infected with influenza virus A/NWS (H0N1). Intermediate glycosylated forms were obtained by the addition of glucosamine to the culture medium; they were characterized after [35S]-methionine labelling by their precursor relationship, by immunoprecipitation and peptide mapping. The underglycosylated hemagglutinins were distributed in classes of discrete molecular weight indicating that glycosylation occurred in a stepwise manner. A total of 8 different bands, suggesting 7 glycosylation sites, was obtained under conditions of both complete and incomplete glycosylation.