Transcriptomic analysis of entomopathogenic fungus Beauveria bassiana infected by a hypervirulent polymycovirus BbPmV-4

Polymycoviridae is a recently established family of mycoviruses. Beauveria bassiana polymycovirus 4 (BbPmV-4) was previously reported. However, the effect of the virus on host fungus B. bassiana was not clarified. Here, a comparison between virus-free and virus-infected isogenic lines of B. bassiana revealed that BbPmV-4 infection of B. bassiana changes morphology and could lead to decreases in conidiation and increases in virulence against Ostrinia furnacalis larvae. The differential expression of genes between virus-free and virus-infected strains was compared by RNA-Seq and was consistent with the phenotype of B. bassiana. The enhanced pathogenicity may be related to the significant up-regulation of genes encoding mitogen activated protein kinase, cytochrome P450, and polyketide synthase. The results enable studies of the mechanism of interaction between BbPmV-4 and B. bassiana.