MOTHER TO FRY, SUCCESSFUL TRANSFER OF IMMUNITY AGAINST INFECTIOUS HEMATOPOIETIC NECROSIS VIRUS-INFECTION IN RAINBOW-TROUT

We have tested whether immunity can be transferred from a mother fish to its fry. Rainbow trout mother fish were inoculated against infectio us haematopoietic necrosis virus (IHNV) by intraperitoneal injection o f a fragment of the IHNV glycoprotein spanning amino acids 31 to 310. This protein fragment was obtained by isolating the specific cDNA from Japanese IHNV strain HV7601 and expressing it in Escherichia coli. Fr y from immunized and control fish were exposed to IHNV at various inte rvals after hatching, and their mortality monitored. Survival of the f ry of immunized fish was significantly greater when exposure to virus occurred 7 days after hatching, and some immunity appeared to persist until at least 25 days after hatching.