Development, Characterization and Early Evaluation of New Modified Live Vaccines Against Columnaris Disease

Abstract

Columnaris disease is an acute to chronic bacterial infection that affects commercial aquaculture and the ornamental fish industry. Flavobacterium columnare, causal agent of columnaris disease, is a facultative pathogen ubiquitous of fresh water environments. Prevention is the best control measure, and vaccination is a feasible alternative. A commercial vaccine is currently available. Extensive genetic studies of the bacteria have led to the distinction of two genomovars within the species, being genomovar II more virulent to catfish. The commercial vaccine belongs to the less pathogenic genomovar. Thus, efforts to develop new vaccines against the most virulent F. columnare type were needed. In this study new rifampicin mutants of F. columnare genomovar II have been developed, fully characterized and tested in lab settings against columnaris infection on catfish. Preliminary results proved that some of the newly developed mutants conferred more protection against columnaris diseases than the current commercial vaccine.