Antiviral Activity of Double Stranded RNA from a Virus isolated from Aspergillus foetidus

IN recent years virus particles with the property of inducing interferon production in animals have been isolated from Penicillium stoloniferum 1,2 , P. funiculosum 2 and P. cyaneofulvum 3 . Virus particles have also been isolated from penicillin producing strains of P. chrysogenum 4 and we have shown that both the particles and derived double stranded RNA are active interferon inducers in animals (unpublished results). Following the observation 5 that a high level of cell wall galactosamine seemed to be associated with the presence of virus particles in P. stoloniferum , we have examined a number of fungi, reported to contain cell wall galactosamine, for possible virus content. One of those examined, Aspergillus niger (strain IMI 146891) ast; , was found to contain polyhedral virus particles; similar particles were also found in a closely related species, A. foetidus (strain IMI 41871). This is the first report of virus particles in the genus Aspergillus . We now describe the isolation and purification of the A. foetidus virus and provide evidence that the RNA isolated from the virus particles is double stranded. We have found that both virus particles and double stranded RNA are active in inducing interferon production and protecting mice against encephalomyocarditis and Semliki Forest viruses.