VP5 is not required for viral replication in vivo and its absence does not alter the virulence characteristics of the virus or the establishment of persistent IPNV infection. The sequence shown is that of Isolate NVI-020. The highly pathogenic isolates NVI-013, NVI-015, NVI-023 and Sp122 have a truncated VP5 protein. Belongs to the avibirnavirus/aquabirnavirus VP5 protein family.