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Biological, serological and molecular variabilities of clover yellow vein virus

Sasaya, T., Shimizu, T., Nozu, Y., Nichiguchi, M., Ihouye, N., Koganezawa, H.
Phytopathology 1997 v.87 no.10 pp. 1014-1019
Trifolium, Clover yellow vein virus, Bean yellow mosaic virus, pathogenicity, host specificity, virulence, immunology, molecular genetics, genes, nucleotide sequences, amino acid sequences, genetic variation, pathotypes, Japan, Australia, New Zealand
A comparative study was made on the host reactions, serological properties, and nucleotide sequences of the coat protein (CP) gene of 10 clover yellow vein virus (ClYVV) isolates and one bean yellow mosaic virus (BYMV) isolate collected from different host plant species and locations in Japan. Two strains of ClYVV isolates, grouped on the basis of host reactions on Chenopodium amaranticolor, C. quinoa, Nicotiana clevelandii, N. benthamiana, Vicia faba, and Trifolium repens, corresponded to two serotypes determined by double-antibody sandwich- and triple-antibody sandwich enzyme-linked immunosorbent assay using three polyclonal and nine monoclonal antibodies. These results were also confirmed by nucleotide sequence analysis of the CP gene. The CP gene of ClYVV isolates of strain 1, including the Australian isolate ClYVV-B, had 93 to 98% nucleotide identities and 97 to 99.6% amino acid identities. The CP of ClYVV isolates of strain 2, including the New Zealand isolate ClYVV-NZ, had 92 to 98% nucleotide identities and 95 to 98% amino acid identities. The nucleotide identities and the amino acid identities between the two ClYVV strains were 82 to 84%, and 90 to 94%, respectively. When compared with the CP sequences of 12 ClYVV isolates, the CP sequence of the BYMV isolate had 71 to 73% nucleotide identity and 73 to 77% amino acid identity. Amino acid sequence differences among ClYVV isolates from strains 1 and 2 were located mostly at the N-terminal regions of the CP. Our results indicated that the ClYVV isolates studied could be separated into two strains on the basis of host reactions, serology, and the nucleotide sequence of the CP gene.