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

The grouper industry in Taiwan faces serious threats from various disease p roblems. The present study investigated dual challenges with infectious pan creatic necrosis virus (IPNV) and Vibrio carchariae in the grouper (Epineph elus sp.). The fish were infected with IPNV for 2 weeks prior to a secondar y infection with the bacteria, or vice versa, by either immersion (10(3)-10 (4) TCID50 IPNV per ml, 10(6)-10(7) colony forming units (CFU) Vibrio per m l) or by intraperitoneal injection (10(3)-10(4) TCID50 IPNV per g fish or 1 0(7) CFU Vibrio/g fish) challenges. Mass mortalities occurred in fish infec ted with IPNV for 2 weeks prior to the infection with the bacteria, or vice versa, in either immersion or intraperitoneal injection challenges. The ba cterium could only survive in seawater or brackish water similar to that of cultured groupers. (C) 1999 Elsevier Science B.V. All rights reserved.