Abstract

Piscirickettsiosis, or salmonid rickettsial septicemia (SRS), caused by Piscirickettsia salmonis, has severely challenged the sustainability of the Chilean salmon industry since its appearance in 1989. P. salmonis is a facultative gram-negative bacterium for which several aspects of its lifecycle relevant for vaccine development (e.g., virulence and pathogenesis) remain poorly understood. Vaccination plays a pivotal role in this strategy, although its efficiency as a procedure will rely on an adequate interpretation of the biological and immunological features of the target pathogen. At present, although this is not the case for P. salmonis and because it has become a serious problem in confined salmon-rearing in Chile, a number of vaccines have been designed and commercialized, so far with moderate effect.