Infection of pronephros cell cultures derived from rainbow trout (Oncorhynchus mykiss, Walbaum) with bacterial fish pathogens: A comparison with whole fish infectivity studies

Primary cell cultures were developed from the pronephros of juvenile rainbow trout (Oncorhynchus mykiss, Walbaum), and used to determine their interaction with bacterial pathogens as compared to whole fish pathogenicity experiments. Overall, there was excellent agreement with Aeromonas hydrophila, A. salmonicida, Citrobacter freundii, Streptococcus iniae, Vibrio anguillarum, V. damsela, V. harveyi, V. ordalii, 'V. viscosus', V. vulnificus and Yersinia ruckeri, which were harmful to cell cultures and pathogenic to Atlantic salmon (Salmo salar L.) and rainbow trout. Also, a culture of Enterococcus faecium, which is not a recognised fish pathogen, caused mortalities in salmonids and damaged the cell cultures. In contrast, negligible damage to fish and/or cell cultures resulted from challenge with a Carnobacterium sp., Escherichia coli, Lactobacillus sp., V. alginolyticus and commercial formalin-inactivated vaccines for enteric redmouth (= Y. ruckeri) and furunculosis (= A. salmonicida). Use of cell cultures and whole fish experiments revealed that inactivation of V. harveyi, for use in vaccines was troublesome, insofar as the addition of formalin and chloroform resulted in harmful preparations. In contrast, cultures of harveyi, which were inactivated by heat (100°C for 1 hour), lysis at pH 9.5 and glutaraldehyde (to 0.5% w/v), were less harmful.