FungallVIetabolites and Viral Replication in Penicillium slo[onij'erlllll

Little is known about the relationship between mycoviruses and fungal secondary metabolism. An in vivo replication system from Penicillium stoloniferum strain NRRL 5267 has been developed to test various fungal products and other antimetabolites against P. stolonlferum fast-moving virus (PsV·f) replication. Initially, cycloheximide was investigated in this test system because of its known antifungal and antiviral activity. Aliquots of 48-h mycelia were incubated in the presence of various metabolites, and after an additional 48-h incubation period, the PsV-f content was measured in A260 units by polyacrylamide gel electrophoresis. Cycloheximide at 1,5, and 10 pg/ml blocked PsV-f replications 40,75, and 95%, respectively, compared to untreated controls. At these levels fungal growth (biomass, dry weight) was unaffected. Therefore, cycloheximide proved to be a rather selective inhibitor of PsV-f replication. Mycophenolic acid, an antiviral metabolite produced by virus (-) strains of P. stolomferum and P. brevi-compactum, at 300 pg/ml, blocked PsV-f replication by 25% but also reduced growth by 36%. Of the fungal metabolites tested, only patulin and gliotoxin inhibited PsV-f replication.