Grapevine berry inner necrosis, a new trichovirus: comparative studies with several known trichoviruses

Summary

Biological, morphological and serological properties of grapevine berry inner necrosis virus (GINV), the causal virus of grapevine berry inner necrosis disease occurring in Japan, were compared with those of several known trichoviruses. Host range and particle length of GINV were quite similar to those of apple chlorotic leaf spot trichovirus (ACLSV). In ultrathin sections of the infected tissues, GINV particles existed in aggregated masses in the cytoplasm of vascular parenchyma and mesophyll cells. No virus specific inclusion bodies, such as pinwheels, viroplasmas or vesicles were observed. Serological relationships were not found between GINV and ACLSV, grapevine virus A or grapevine virus B. The cDNAs of the 3′-terminal region of the GINV genome were synthesized from poly (A)⁺RNAs extracted from infected tissues by PCR-selected cDNA subtraction and 3′-RACE PCR. The sequence of the 3′-terminal 2 469 nucleotides contained three open reading frames (ORF) encoding a protein with the conserved motifs of RNA polymerase (ORF1), a 39 kDa putative movement protein (ORF2) and a 22 kDa protein (ORF3). The 22 kDa protein expressed in Escherichia coli reacted with antiserum against GINV, indicating that it is the coat protein of GINV. Polymerase and coat protein amino acid sequence comparisons and phylogenetic analyses with nine species of the genera Trichovirus and Capillovirus indicated that GINV is a new trichovirus relatively close to ACLSV.