Genome sequence, full-length infectious cDNA clone, and mapping of viral double-stranded RNA accumulation determinant of hypovirus CHV1-EP721.

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TitleGenome sequence, full-length infectious cDNA clone, and mapping of viral double-stranded RNA accumulation determinant of hypovirus CHV1-EP721.
Publication TypeJournal Article
Year of Publication2007
AuthorsLin, H, Lan, X, Liao, H, Parsley, TB, Nuss, DL, Chen, B
JournalJ Virol
Volume81
Issue4
Pagination1813-20
Date Published2007 Feb
ISSN0022-538X
KeywordsAscomycota, Cloning, Molecular, Codon, DNA, Complementary, Genome, Viral, Molecular Sequence Data, Open Reading Frames, Plant Diseases, Plants, RNA Viruses, RNA, Double-Stranded, RNA, Viral, Sequence Homology, Amino Acid, Sequence Homology, Nucleic Acid, Transfection, Virulence
Abstract

Cryphonectria parasitica strain EP721 is infected with a strain of hypovirus CHV1, CHV1-EP721, and exhibits typical hypovirulence-associated traits such as reduced pigmentation and reduced asexual sporulation. However, the accumulation of the viral double-stranded RNA (dsRNA) in this hypovirus-infected C. parasitica strain is atypically low. We now report the complete nucleotide sequence and construction of a full-length infectious cDNA clone for hypovirus CHV1-EP721. The genome sequence of CHV1-EP721 was determined to be 12,724 bp in length and to share extensive homology with two other hypovirus strains, CHV1-Euro7 and CHV1-EP713, with an average of 99% and 90% identities at the nucleotide level and 99% and 92% identities at the amino acid level, respectively. CHV1-EP721 was successfully introduced into virus-free fungal host strain EP721(-v) by transfection with transcripts derived from a full-length viral cDNA. The transfected strain had a phenotype indistinguishable from that of EP721, and the accumulation of CHV1-EP721 dsRNA in the transfectant was lower than those transfected by CHV1-Euro7 and CHV1-EP713 transcripts. Through the construction of chimeric viruses by domain swapping using infectious cDNA clones of CHV1-EP721, CHV1-EP713, and CHV1-Euro7 hypoviruses, the determinant for the low level of viral dsRNA accumulation in CHV1-EP721 was mapped to the second of two CHV1-EP721 open reading frames (ORFs), ORF B. Further refined swapping of domains within ORF B identified a 2.5-kb coding region between p48 and the polymerase domain of CHV1-EP721 as being responsible for the low viral dsRNA accumulation. Evidence is also provided that low rates of hypovirus transmission through conidial spores correlates with low viral dsRNA accumulation.

DOI10.1128/JVI.01625-06
Alternate JournalJ. Virol.
PubMed ID17135313
PubMed Central IDPMC1797589
Grant ListAI07510-3 / AI / NIAID NIH HHS / United States
GM55981 / GM / NIGMS NIH HHS / United States