Dual challenges of infectious pancreatic necrosis virus and Vibriocarchariae in the grouper, Epinephelus sp.

The grouper industry in Taiwan faces serious threats from various disease problems. The present study investigated dual challenges with infectious pancreatic necrosis virus (IPNV) and Vibriocarchariae in the grouper (Epinephelus sp.). The fish were infected with IPNV for 2 weeks prior to a secondary infection with the bacteria, or vice versa, by either immersion (103–104 TCID50 IPNV per ml, 106–107 colony forming units (CFU) Vibrio per ml) or by intraperitoneal injection (103–104 TCID50 IPNV per g fish or 107 CFU Vibrio/g fish) challenges. Mass mortalities occurred in fish infected with IPNV for 2 weeks prior to the infection with the bacteria, or vice versa, in either immersion or intraperitoneal injection challenges. The bacterium could only survive in seawater or brackish water similar to that of cultured groupers.