Identification and characterisation of infectious salmon anaemia virus (ISAV) haemagglutinin gene highly polymorphic region (HPR) type 0 in North America.

Abstract

Increasing evidence suggests that infection of Atlantic salmon with infectious salmon anaemia virus (ISAV) does not always result in clinical disease. Recently it has been suggested that differential strain virulence is associated with differences in the 3’ end of the ISAV haemagglutinin (HA) gene referred to as the hypervariable or highly polymorphic region (HPR). In particular it has been hypothesized that a full length variant containing the maximum number of amino acids in the variable region, referred to as HPR0, may be the ancestral progenitor of virulent strains associated with intensive aquaculture. In this current communication we describe the first identification and characterization of an HPR0-like variant in North America and discuss the implications of this finding for fish health management and future ISAV research.