STUDY OF THE INTERACTION BETWEEN A PERSISTENT INFECTIOUS PANCREATIC NECROSIS VIRUS (IPNV) INFECTION AND EXPERIMENTAL INFECTIOUS SALMON ANEMIA (ISA) IN ATLANTIC SALMON, SALMO-SALAR L

An infectious pancreatic necrosis virus (IPNV) carrier stock of Atlant ic salmon parr (100 g) was divided between two tanks and inoculated ex perimentally with tissue homogenate containing the aetiologic agent of infectious salmon anaemia (ISA) and non-ISA tissue homogenate (contro l), respectively. Plasma and kidney samples from ISA-infected and cont rol fish were taken twice weekly for 25 days. In the kidney samples, I PNV was quantified by a plaque assay. In plasma, anti-IPNV antibodies were measured using an indirect ELISA. The ISA-infection did not seem to activate the IPNV-infection. Neither the proportion of fish with IP NV or anti-IPNV antibodies, nor the IPNV titre or level of anti-IPNV a ntibodies showed any specific trend during the study. Independently of ISA, IPNV was detected in 54 out of 132 fish (41%), while 71 out of 1 95 fish (36%) had plasma antibodies against IPNV. No association was f ound between detection of IPNV, and presence or level of anti-IPNV ant ibodies in individual fish.