Molecular analysis of Fiji disease Fijivirus genome segments 1 and 3

Fiji disease fijivirus (FDV) genomic segments 1 (S1) and 3 (S3) were completely sequenced. FDV S1 comprised 4,532 nt and was predicted to encode a 170.6 kDa protein. FDV S3 comprised 3,623 nt and was predicted to encode a 135.5 kDa protein. The terminal sequences of S1 and S3 were 5' AAGUUUUU......CAGCUAGCGUC 3' and 5' AAGUUUUU......CAGCAGAUGUC 3', respectively, and located immediately adjacent to these sequences were 12 bp imperfect inverted repeats. The predicted translation product of FDV S1 showed highest similarity to Rice black-streaked dwarf virus (RBSDV) S1 and is thought to encode the viral RNA-dependent RNA polymerase (RdRp). The predicted translation product of FDV S3 was found to be most similar to RBSDV S4 which is thought to encode the 'B-spike' protein. The FDV sequence contained an ATP/GTP binding motif and a leucine zipper motif, but these motifs were not found in the RBSDV sequence. Phylogenetic analysis based on the amino acid sequences of the RdRp of FDV S1 and other reoviruses revealed that the fijiviruses form a cluster close to the oryzaviruses. The RdRp sequences were grouped into genera that were consistent with the current reovirus classification scheme that is based on physico-chemical and biological properties.