Abstract
Infectious pancreatic necrosis virus can be transmitted through cohabitation from Atlantic cod (Gadus morhua) to Atlantic cod, Atlantic salmon (Salmo salar), Atlantic halibut (Hippoglossus hippiglossua), and lumpfish (Cyclopterus lumpus)
Introduction:
In the aquaculture industry, diseases caused by viral pathogens has a great impact on fish welfare and cause major losses of fish. Atlantic cod (Gadus morhua ) farming in Norway has seen a steadily growth in the recent years. With the increase in expansion of Atlantic cod farming, it is necessary to assess whether pathogens could spread to and between the different species in the aquaculture industry. Infectious pancreatic necrosis virus (IPNV) is a fish pathogen with a broad host range and has caused economically severe losses in Atlantic salmon (Salmon salar ) farming. Increasing the knowledge of IPNV transmission between fish species represents a first ans essential step for enhancing biosecurity and disease management to protects the aquaculture industry.
Methodology:
In this study, we investigated whether IPNV-injected Atlantic cod (using intraperitoneal (ip) injection) could shed IPNV into rearing water and thus transmit the virus to other fish species important to Norwegian aquaculture; Atlantic halibut (Hippoglossus hippoglossus ), Atlantic salmon and lumpfish (Cyclopterus lumpus ) using a cohabitation experimental trial method.
Virus shedding into tank water, fish mortality and gross pathology were assesses throughout the experimental period (42 days). Tissue samples from gills, heart, spleen and kidney were used for PCR detection of IPNV and histopathological examinations, were collected. In addition, samples of pyloric caeca with pancreas tissue were included for the histopathological examinations.
Results and conclusions:
We confirmed lesions consistent with infectious pancreatic necrosis (IPN) by histopathology and immunohistochemistry in ip-injected Atlantic cod and in cohabitant Atlantic halibut. In addition, cohabitant fish of all four species (Atlantic cod, Atlantic salmon, Atlantic halibut and lumpfish) tested positive for IPNV by PCR. However, except for Atlantic halibut only low virus levels in a few individuals were detected. Nevertheless, our study suggests that IPNV-injected Atlantic cod can transfer IPNV with the possibility of causing an infection to these species. These findings highlight the risk of interspecies transmission of pathogens among farmed fish. It also demonstrates the importance to understand infectious fish disease epidemiology to improve biosecurity measures in aquaculture.