Publication Abstract

Serological classification ofinfectious pancreatic necrosis (IPN) virus and other aquatic birnaviruses

B.J. Hill and K. Way

Aquatic birnaviruses infect alarge variety of fish, molluscs and crustacea in the freshwater, estuarine and marineenvironments throughout the world and yet despite this extensive host range andgeographical distribution, the vast majority of isolates have been found to beantigenically-related to the original reference serotypes (VR299, Sp and Ab) of infectiouspancreatic necrosis virus (IPNV) of salmonids. However, in early studies it was seen thatthere is a high degree of antigenic diversity amongst isolates with some reacting onlyrelatively weakly with these three traditional serotypes, suggesting that other serotypesmay exist. In this review we examine the published studies on the degrees of antigenicrelatedness between IPNV isolates and other aquatic birnaviruses and discuss the attemptsby various authors to identify and/or define different serotypes. The published data fromserum neutralization tests is critically appraised and the factors influencingneutralization results discussed. Details are then presented of our owncross-neutralization study with almost 200 isolates of IPNV and other aquatic birnavirusesusing a standardized procedure. On the basis of the limit we set for the maximum degree ofdifference from a reference serotype for an isolate to belong to that serotype, theisolates we examined could be divided into two distinct serogroups (which do notcross-react), the first containing nine serotypes and the second containing a singleserotype. We propose a change from the traditional terminology of the recognised referenceserotypes to a new simplified system: Serogroup A containing serotypes A₁ to A₉(so far), and Serogroup B containing the single serotype B₁) (so far). The useof panels of selected monoclonal antibodies against one or more of these referenceserotypes offers the prospect for a simpler method for serotyping new isolates andidentifying new serotypes. In limited studies to date, reaction patterns with panels ofmonoclonal antibodies in immunodot and ELISA tests have, in the main, substantiated theserotype classification scheme achieved by serum neutralization tests.

Reference:

B.J. Hill and K. Way, 1995. Serological classification of infectious pancreatic necrosis(IPN) virus and other aquatic birnaviruses. Annual Review of Fish Diseases, 5: 55-77