ARS | Publication request: Towards the intelligent design of a vaccine against Edwardsiella ictaluri

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: December 1, 2011
Publication Date: N/A

Technical Abstract: Edwardsiella ictaluri is the leading cause of disease loss in the catfish industry in the United States, accounting for an estimated 20.2 % loss in 2009. Previous work to establish live-attenuated vaccines for E. ictaluri demonstrated a relatively weak channel catfish immune response, with better immunity following a booster dose. Although a live-attenuated vaccine of unknown genetic make-up is commercially available, the efficacy is poor and the primary response indicator is a slight increase in food conversion . Only 12.3 % of fish produced were vaccinated in 2009. With a long term goal of developing an efficacious live-attenuated vaccine to control E. ictaluri in channel catfish, in-depth knowledge of E. ictaluri pathogenesis will allow intelligent selection of a specific gene or a combination of genes as candidates for mutagenesis for vaccine development. The best candidates will attenuate virulence, maximize persistence in the tissues, and remove any immuno-suppressive activity associated with pathogenesis. Vaccination with the resulting live-attenuated vaccine will lead to the activation of a strong, efficacious immune response. Recent work has enabled the development of a preliminary model for E. ictaluri pathogenesis that includes participation of a Type III secretion system (T3SS), a urease enzyme, and a Type 6 secretion system (T6SS). All are essential to intracellular replication and virulence in channel catfish. Details of the role these virulence factors play in E. ictaluri pathogenesis will be presented, as well as a discussion of the potential for mutation of various components to produce a highly efficacious live attenuated vaccine.