Flavobacterium psychrophilum vaccine development: a difficult task

Abstract

Bacterial cold water disease (BCWD) is a globally distributed freshwater fish disease caused by the Gram-negative bacterium Flavobacterium psychrophilum. It is a particularly devastating infection in fry salmonids and may lead to high levels of mortality. In spite of its economic impact on fish farms, neither the biology of the bacterium nor the bacterium–host interactions are well understood. This review provides a synopsis of the major problems related to critical remaining questions about research into the use of vaccines against F. psychrophilum and the development of a commercial vaccine against this disease. Studies using sera from convalescent rainbow trout have shown the antigenic properties of different proteins such as OmpH, OmpA and FspA, as well as low and high molecular mass lipopolysaccharide of F. psychrophilum, which are potential candidates for subunit vaccines. Inactivated F. psychrophilum bacterins have been successfully tested as vaccines under laboratory conditions by both immersion and intraperitoneal routes. However, the efficacy and the practical usefulness of these preparations still have to be proved. The use of attenuated and wild-type strains to immunize fish showed that these systems offer high levels of protection. Nevertheless, their application clashes with the regulations for environmental protection in many countries. In conclusion, protective vaccines against BCWD are theoretically possible, but substantial efforts still have to be made in order to permit the development of a commercial vaccine.

Differential expression of long non-coding RNAs in three genetic lines of rainbow trout in response to infection with Flavobacterium psychrophilum

“…Live-attenuated Fp vaccines can provide protection against BCWD but environmental safety is a concern (see review ref. 6). …”

Entericidin Is Required for a Probiotic Treatment (Enterobacter sp. Strain C6-6) To Protect Trout from Cold-Water Disease Challenge

“…The Gram-negative bacterium F. psychrophilum causes acute and commonly fatal septicemic infections in young salmonid fry (12,13) and other fish species (14) and severe economic losses in older fish populations, due to reduction of product value, anatomical deformities, and high treatment costs (15)(16)(17). Currently, there is no commercial vaccine available to control BCWD (18). Improved rearing conditions (e.g., stress reduction, reduced stocking densities, cleaner raceways, adjusted feeding strategies, and improved disinfection protocols) and antimicrobials are the only practical control measures.…”

Assessment of cross‐protection to heterologous strains of Flavobacterium psychrophilum following vaccination with a live‐attenuated coldwater disease immersion vaccine

“…However, there are increasing reports of antibiotic resistance in F. psychrophilum (Cipriano & Holt, ; Henríquez‐Núñez, Evrard, Kronvall, & Avendaño‐Herrera, ; Hesami et al., ; Van Vliet, Loch, Smith, & Faisal, ) and the number of antibiotics available for treatment of BCWD is limited. As such, there have been significant efforts to develop an effective vaccine against BCWD (Gomez, Mendez, Cascales, & Guijarro, ).…”