Sequence relatedness of Palyam virus genes to cognates of the Palyam serogroup viruses by RNA-RNA blot hybridization.

Cognate genes of nine members of the Palyam serogroup of orbiviruses have been identified and their relatedness to the prototype, Palyam virus, has been determined. Viral dsRNA segments were electrophoresed through 10% polyacrylamide gels, transferred to membranes, and hybridized to labeled RNA from Palyam virus under hybridization conditions using 52 degrees, 50% formamide, 5 X SSC. Cognate genes of each virus isolate were identified by hybridizing their genomes to [5'-32P]pCp-labeled, isolated segments from Palyam virus. Single segments from Palyam hybridized to no more than one segment in the other isolates. Nine of the 10 genes exhibited nucleic acid sequence homology between Palyam and seven of the other eight isolates. Gene 2 of Palyam hybridized only with gene 2 of CSIRO Village, and it was correlated with serotype specificity. Since CSIRO Village is the only member of the serogroup which cross-reacts with Palyam in neutralization tests, gene 2 may encode the neutralization antigen. Variation in the intensity of the hybridization signals of the remaining nine genes within a given virus indicated that the number and identity of conserved genes differed between members of the group. Genes 5, 7, and 9 were the most conserved genes for all members of the serogroup, while the levels of relatedness of Palyam genes 1, 3, 4, 8, and 10 to their cognates in the other isolates varied under these hybridization conditions.