Molecular Characterization of a Debilitation-Associated Partitivirus Infecting the Pathogenic Fungus Aspergillus
Yinhui Jiang1,2, Jingxian Wang3, Bi Yang1,2
1Key Laboratory of Endemic and Ethnic Diseases, Guizhou Medical University, Ministry of Education, Guiyang, China.
Abstract:
The opportunistic human pathogenic fungus Aspergillus flavus is known to be infected with mycoviruses. In this study, we report a novel mycovirus A. flavus partitivirus 1 (AfPV1) that was originally isolated from the abnormal colonial morphology isolate LD-3-8 of A. flavus. AfPV1 has spherical virus-like particles about 40 nm in diameter, and three double-stranded RNA (dsRNA) segments (dsRNA1, 2, and 3 with lengths of 1.7, 1.4, and 1.1 kbp, respectively) were packaged in the virions. dsRNA1, dsRNA2, and dsRNA3 each contained a single open reading frame and potentially encoded 62, 42, and 32 kDa proteins, respectively. The dsRNA1 encoded protein shows similarity to the RNA-dependent RNA polymerase (RdRp) of partitiviruses, and the dsRNA2 product has no significant similarity to any other capsid protein (CP) in the GenBank databases, beside some homology with the hypothetical "capsid" protein of a few partitiviruses. The dsRNA3 encodes a protein with no similarity to any protein in the GenBank database. SDS-PAGE and polypeptide mass fingerprint-mass spectrum (PMF-MS) analyses indicated that the CP of the AfPV1 was encoded by dsRNA2. Phylogenetic analysis showed that the AfPV1 and relative viruses were found in an unclassified group inside the Partitiviridae family. AfPV1 seems to result in debilitation symptoms, but had no significant effects to murine pathogenicity. These findings provide new insights into the partitiviruses taxonomy and the interactions between viruses and A. flavus.
Insights
A novel mycovirus, Aspergillus flavus partitivirus 1 (AfPV1), was identified in Aspergillus flavus. This virus causes debilitation symptoms in the fungus but does not affect its pathogenicity in mice.
Area of Science:
- Mycology
- Virology
- Fungal Genetics
Background:
- The opportunistic human pathogenic fungus *Aspergillus flavus* is known to harbor mycoviruses.
- Understanding these viral infections is crucial for comprehending fungal biology and pathogenicity.
Purpose of the Study:
- To report the discovery and characterization of a novel mycovirus, *Aspergillus flavus* partitivirus 1 (AfPV1).
- To investigate the genomic structure, protein products, and phylogenetic placement of AfPV1.
- To assess the impact of AfPV1 infection on *A. flavus* morphology, growth, and pathogenicity.
Main Methods:
- Isolation of AfPV1 from an *A. flavus* isolate with abnormal colonial morphology.
- Analysis of virus-like particles, including size and morphology.
- Extraction and characterization of double-stranded RNA (dsRNA) segments.
- Open reading frame (ORF) prediction and protein homology searches.
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and polypeptide mass fingerprint-mass spectrum (PMF-MS) analysis.
- Phylogenetic analysis of viral sequences.
Main Results:
- A novel partitivirus, AfPV1, was isolated from *A. flavus*.
- AfPV1 possesses spherical virus-like particles (approx. 40 nm) containing three dsRNA segments (1.7, 1.4, and 1.1 kbp).
- AfPV1 dsRNA segments encode potential proteins of 62, 42, and 32 kDa, with the 42 kDa protein identified as the capsid protein (CP).
- Phylogenetic analysis places AfPV1 within an unclassified group of the *Partitiviridae* family.
- AfPV1 infection causes fungal debilitation but does not significantly alter murine pathogenicity.
Conclusions:
- AfPV1 represents a newly identified member of the *Partitiviridae* family, expanding the known diversity of fungal viruses.
- The characterization of AfPV1 provides new insights into partitivirus taxonomy and evolution.
- AfPV1 infection impacts *A. flavus* biology, highlighting the complex interactions between fungi and their associated viruses.
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