Purpose: In recent years, Increasing numbers of viruses infecting fungi have been identified. In this study, we used an in silico approach for the analysis of deep RNA sequencing results in order to identify and characterize putative genomic ssRNA or dsRNA molecules of mycoviruses in Aspergillus fumigatus.
Methods: RNA sequencing reads from transcriptome analysis of itraconazole treated Aspergillus fumigatus strains were mapped against the Af293 reference genome of A. fumigatus using CLC Genomic Workbench. Unmapped reads were collected and used for de novo assembly. Contigs were analyzed by Blastx comparison with a mycovirus protein database using standalone NCBI Blast. Assembled viral genomes were used as template for remapping of RNA sequencing reads.
Results: In total, deep RNA sequencing results from 11 Aspergillus fumigatus strains were analyzed for the presence of mycoviral genomic RNAs. In 9 out of 11 strains, putative mycovirus RNA genomes were identified. Three strains were infected with two different mycovirus species. Two strains were infected with Aspergillus fumigatus tetramycovirus type 1 (AfuTMV-1). Four strains contained genomic RNA of an unknown narna-like virus which showed 38% amino acid sequence identity to Beihai narna-like virus 21. Three strains contained genomic RNA of an unknown narna-like virus which showed 47% amino acid sequence identity to Fusarium poae narnavirus 2. Two strains contained genomic RNAs of an unknown partitivirus which showed 50% amino acid sequence identity to Alternaria alternata partitivirus 1. Finally, one strain contained genomic RNA of an unknown mitovirus which showed 34% amino acid sequence identity to Sclerotina sclerotiorum mitovirus.
Conclusion: In silico analysis of deep RNA sequencing results showed that a majority of the Aspergillus fumigatus strains used in this study, were infected with mycoviruses. Four novel Aspergillus fumigatus RNA mycoviruses could be identified: Two different A. fumigatus narna-like viruses, one A. fumigatus partitivirus, and one A. fumigatus mitovirus. Further molecular and virological characterization is ongoing.
Full conference title:
- AAA 8th (2018)