Peanut yellow spot virus: A distinct tospovirus species based on serology and nucleic acid hybridisation

Nucleocapsids of peanut yellow spot virus (PYSV), purified from peanut (= groundnut) plant tissue, contained a protein with a molecular mass of 29 kDa. In ELISA and immuno-blot analysis the virus did not react with tomato spotted wilt virus (TSWV), Impatiens necrotic spot virus (INSV) and peanut bud necrosis virus (PBNV) antisera. PYSV contained three RNA species, a large (L) RNA (c.8900 nucleotides), a medium (M) RNA (c.4800 nucleotides) and a small (S) RNA (c.3000 nucleotides), similar to other tospoviruses. In addition, a fourth RNA species of approximately 1800 nucleotides was also present in purified preparations. Hybridisation analysis under high stringency conditions revealed no hybridisation between PYSV RNAs and cDNA probes representing the nucleocapsid (N) gene, the glycoprotein (GP) gene and the 3' half of the RNA polymerase gene of PBNV. PYSV genomic RNAs also failed to hybridise with cDNA probes from the GP genes of TSWV and INSV. In reciprocal tests, the cDNA clones of PYSV S and M RNAs did not hybridise with any of the PBNV RNAs. Based on the absence of serological relationships between PYSV and PBNV, TSWV and INSV and lack of nucleotide homology based on hybridisation studies between the PYSV RNAs and cDNA clones from PBNV, TSWV and INSV, PYSV should be considered as a distinct species of the genus Tospovirus under a new serogroup, putatively designated ‘V’.