Introduction

Francisella is an intracellular bacterium that causes the systemic granulomatous inflammatory disease francisellosis in cod. VESO Aqualab offers challenge models with Francisella sp.

Challenge models to evaluate the effect of vaccination

Cod are acclimatized for a minimum of one week before challenge by i.p. injection or immersion. After challenge, mortality is recorded during an observation period of two to three weeks. Evaluation of the potency of the vaccine is based on differences in mortality in vaccinated and unvaccinated fish.

Diagram 1: Challenge by intraperitoneal injection

Diagram 2: Challenge by immersion

Mortality in groups of unvaccinated cod challenged with different doses of Francisella sp.