Mengovirus-induced cytopathic effect in L-cells: protective effect of interferon

The effect of interferon on mengovirus-induced cytopathic effect (CPE) in L cells, the cut-off of host-cell protein synthesis, and production of mature virus were found to be dependent on the concentration of interferon. CPE and inhibition of host protein synthesis were not affected until the concentration of interferon was increased 100-fold over that required to reduce viral yields by 90%.

Induction of interferon by preparations of synthetic single-stranded RNA

A study was undertaken to help determine whether synthetic nonbase-paired, single-stranded RNA as well as synthetic base-paired, double-stranded RNA could induce interferon. Synthetic polyriboinosinic acid and polyribocytidylic acid induced interferon and interferon-like resistance in several different cell culture systems. However, in the intact rabbit only the most active preparations of single-stranded RNA induced circulating interferon when injected intravenously. The induced interferon and antiviral effect in tissue culture and animals was shown to have characteristics of the interferon system. Contamination of the single-stranded synthetic RNA materials by small amounts of base-paired, double-stranded RNA was ruled out by failure to find sufficient heterologous nucleic acid bases by differential activities of single-stranded and double-stranded RNA's in different cell systems and by failure to detect double-stranded RNA in poly-rI upon chromatography on benzoylated DEAE-cellulose.

The pathogenesis of autoimmunity in New Zealand mice, I. Induction of antinucleic acid antibodies by polyinosinic-polycytidylic acid

Antibodies to DNA and RNA were induced in young NZB/NZW F(1) (B/W) female mice following multiple injections of the interferon-inducer polyinosinic.polycytidylic acid (poly I.poly C). Despite serum concentrations of interferon adequate to inhibit the C-type murine leukemia viruses, there was an acceleration of the autoimmune disease in these animals. Anti-RNA, but not anti-DNA antibodies, were induced in B/W male mice, as well as in NZB and NZW mice. Anti-RNA antibodies were also found in 50 per cent of female B/W mice who had never received poly I.poly C and in 8 of 24 sera from patients with systemic lupus erythematosus. These results suggest that double-stranded RNA functions as a potent antigen in New Zealand mice. Naturally occurring nucleic acids (e.g., viruses) probably act as stimuli to a genetically hyperreactive immune system. According to this hypothesis, the unusual feature in this disease is not a unique virus, but rather the unique genetic susceptibility of the B/W (particularly female) host to immunization with nucleic acids. A similar pathogenetic mechanism may be operative in some humans with systemic lupus erythematosus.

Virus-induced sarcoma of mice: inhibition by a synthetic polyribonucleotide complex

The availability of a potent inducer of interferon, the synthetic double-stranded RNA (poly I.poly C), prompted us to determine its possible prophylactic and/or therapeutic effect on virus-induced sarcomas of mice. When treatment was begun prior to virus inoculation and repeated on alternate days, the majority of NIH Swiss mice inoculated with Moloney or Friend pseudotypes of Moloney murine sarcoma virus failed to develop tumors. Other experiments suggested that repeated injections initiated even after the establishment of tumor nodules were also effective. Mice injected on the day of birth with poly I.poly C develop high titers of interferon. The evidence favors, but does not establish, the interpretation that the observed tumor inhibition is mediated through the induction of endogenous interferon. These experiments demonstrate that treatment with poly I.poly C is followed by a regression of established murine sarcoma infection in mice.

The effect of an interferon inducer on influenza virus

The double-stranded complex of polyriboinosinic acid and polyribocytidilic acid (poly I.poly C) was shown to inhibit effectively the infection of human cells with 4 common human respiratory pathogens-influenza A2, rhinovirus 13, respiratory syncytial and parainfluenza-1 viruses. This protection was observed with levels of poly I.poly C which did not induce the release of detectable amounts of interferon. Mice could be protected from pulmonary influenza A2 infections by intranasal instillation of poly I.poly C before challenge with virus. Administration of poly I.poly C directly to the respiratory tract was found superior to systemic administration in the case of the pulmonary infection studied.

Herpetic keratoconjunctivitis: therapy with synthetic double-stranded RNA

A study was undertaken in rabbits to determine how late in the course of keratoconjunctivitis caused by herpes simplex recovery could be effected by an inducer of interferon. Interferon was induced by means of synthetic double-stranded RNA copolymer formed with polynosinic acid: polycytidilic acid RNA. Therapy promotes recovery from severe and fully established keratoconjunctivitis for which treatment was begun as late as 3 days after virus inoculation. No drug toxicity was observed in the therapeutic dose range. These findings further support the proposed role of the interferon mechanism in the natural recovery of already established viral infection. They also suggest the usefulness of interferon inducers in viral infections of man.