Enhancement of fish mortality by rhabdovirus infection after immunization with a viral nucleoprotein peptide.

A similar sequence to a mouse immunodominant CTL peptide (SYVLQGN, single-letter amino acid code, conserved amino acids underlined) identified in the nucleoproteins of several strains of vesicular stomatitis virus (VSV) (37) was found in the nucleoproteins of viral hemorrhagic septicemia virus (VHSV) of salmonid fish (GYVYQGL in VHSV 07.71 and GYVYQGS in VHSV Makah) and not in the nucleoproteins of other rhabdoviruses. The in vivo immunization of fingerling salmonid fish (rainbow trout Onchorynchus mykiss, W) with this VHSV peptide and their subsequent challenge with VHSV resulted in the enhancement rather than in the reduction of fingerling trout mortality. Possible implications for the development of subunit vaccines against VHSV are discussed.