INFECTIOUS HEMATOPOIETIC NECROSIS VIRUS FROM SALMONIDS CULTURED IN KOREA

Four isolates of infectious haematopoietic necrosis virus (IHNV) were obtained from rainbow trout, Oncorhynchus mykiss (Walbaum), and masu s almon, Oncorhynchus masou (Walbaum), fry during epizootics at hatcheri es in Korea. The four isolates of IHNV were compared with three from s almonids in the USA (SRCV, OSV and RB-76) by analysis of virion protei ns in sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS- PAGE) and neutralization tests, with two monoclonal antibodies raised against SRCV (MAb SRCV/A4) and RB-76 (MAb RB/B5). Based on the antigen icity and the size of the structural proteins, one Korean isolate from masu salmon (SCS) is similar to RB-76 and is an electropherotype 1. T he other three isolates from rainbow trout (PRT, YRT and MRT) were ide ntical to each other in the mobilities of their virion proteins in SDS -PAGE, and although their nucleocapsid (N) proteins comigrated with th at of the RB-76 isolate, they differed from RB-76 in the smaller matri x 2 (M2) protein they contained. In addition, the three Korean isolate s (PRT, YRT and MRT) could be divided into two groups by reactivity wi th MAb RB/B5. While the YRT isolate was neutralized by this MAb, the P RT and MRT isolates were not, suggesting that there are at least two n eutralizing antigenic variants of IHNV in Korea.