Relative resistance of juvenile Atlantic cod to oral and immersion infection with VHSV mimicking natural routes of exposure

摘要

Juvenile Atlantic cod (Gadus morhua) were experimentally infected with a genotype III VHSV isolate recovered from wild caught cod in Scotland using oral, immersion and intra-peritoneal infection routes. High mortalities and clinical disease occurred in i.p infected fish but no evidence of infection was obtained following immersion or oral challenge, despite the use of a highly sensitive real-time PCR detection method. Together these results suggest a natural resistance to the development of disease in cod following exposure to horizontal transmission of virus under simulated natural conditions. However, cod are known to be naturally infected carriers of VHSV and as such exposure to and maintenance of VHSV in aquaculture populations could pose a potential risk of evolution of new pathogenic variants as has apparently repeatedly occurred in the case of marine farmed rainbow trout.