DAO prepress abstract  -  doi: 10.3354/dao01914

ABSTRACT: Betanodaviruses, the causative agents of viral nervous necrosis in marine fish, have bipartite positive-sense RNA genomes and have been classified into four genotypes, TPNNV, BFNNV, SJNNV, and RGNNV, based on analysis of RNA2 sequences. Full-length genomes of TPNNV and BFNNV were sequenced for the first time in this study. Their sequence data and those of SJNNV and RGNNV retrieved from GenBank were compared with each other to investigate the relationships among the four genotypes. Between TPNNV and BFNNV, sequence identities were relatively high in RNA1 and encoded protein A but were not significantly high in RNA2 or the coat protein (CP). Similarly, between BFNNV and RGNNV, the amino acid sequences of CP were highly similar but identities of RNA1, RNA2, and protein A sequences were not especially high. Furthermore, multiple alignment data of the four genotypes of RNA2 sequences revealed that the TPNNV and SJNNV sequences shared the same sizes of gaps or extra sequences at the same positions. Collectively, these apparent contradictions in sequence identity suggest that betanodavirus genomes have been constructed via complex evolutionary processes.