Optimised vaccines deliver improved animal health and avoid use of antimicrobials in the production of fish (Sommerset et al., Expert Review Vaccines 2005, 4, 89-101.). Australian YTK Photobacteriosis outbreaks have been reported in association with Photobacterium damselae subsp damselae (Pdd), Photobacterium damselae subspecies piscicida(Pdp) and various Vibrio harveyi(Vh) isolates (Matt Landos, Nicky Buller, unpublished). To support stable production of high quality finfish highly efficacious controls of microbial diseases are critical. Successful examples are currently employed in salmon (Yersinia ruckeri, Vibrio anguillarum) and barramundi (Streptococcus iniae) whereby disease outbreaks drove the need for vaccine development. These conditions are now both well controlled in vaccinated populations and have dramatically reduced reliance on administration of antibiotics.
Currently, crude autogenous vaccines are in use with YTK for control of only Pdd in South Australia and Western Australia with some reported success. Recently Pdp has emerged as a significant pathogen in South Australian outbreaks. Reliable vaccination against Pdp has proven difficult in international experience using traditional autogenous and generic killed vaccine methods, hence increasingly research is exploring DNA vaccination methods to improve protection against this pathogen (Kato et al., Vaccine 2015, 33 (8), 1040-1045). It is also probable that antigenic diversity had been underestimated, given high diversity that recent sequencing technology has revealed in our preliminary research . Preparedness for the emergence of highly pathogenic Pdp strains is prudent to allow rapid controls to be developed, without incurring business-ending losses within the growing aquaculture sector, or having high levels of reliance on oral antibiotics. Genetic sequence data on isolates generated through this project can be used for epidemiological modelling, new rapid diagnostic typing tools and immediate response if disease emergence occurs in other finfish industries. Pdp is acknowledged as a serious pathogen internationally in species including yellowtail, cobia, flounder, seabream, pompano and sea bass. (Andreoni et al.J Immunol Res. 2014).