An overview of vaccine development strategies for columnaris-causing bacteria in cultured fish

Authors: HARRISON, COURTNEY - Auburn University; Lafrentz, Benjamin; Shoemaker, Craig; Lange, Miles; LILES, MARK - Auburn University; MOHAMMED, HAITHAM - Texas A&M University; Beck, Benjamin; CHURCHMAN, EMILY - Auburn University; PEATMAN, ERIC - Harvest Select Farms; BRUCE, TIMOTHY - Auburn University

Submitted to: Journal of Fish Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/16/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: Columnaris disease, caused by columnaris-causing bacteria (CCB) affects freshwater fish species worldwide. CCB are yellow-pigmented bacteria that are abundant in freshwater. Outbreaks of columnaris disease typically occur following stressful events, where CCB attach and colonize the skin and gills. As such, several surface disinfectants are used in combination with good management practices to prevent outbreaks of the disease. An appealing method for the prevention of columnaris disease is vaccination, and has been practiced since the 1970’s. Many different types of vaccines have been intensely researched, including killed, live-attenuated, recombinant, and micro- and nano-particle vaccines against columnaris disease. The development of an effective columnaris vaccine has been limited partially due to not fully understanding the genetic diversity of CCB. The classification of CCB has changed throughout the last century, including prior categorization into genomovars, then genetic groups. Additionally, CCB have fish host associations related to virulence. Recently, Flavobacterium columnare was recognized as representing four CCB species, including F. columnare, F. covae, F. davisii, and F. oreochromis. With this new discovery, columnaris vaccination development has been reinitiated and focuses on targeting appropriate host species.

Technical Abstract: Columnaris disease caused by columnaris-causing bacteria (CCB) affects cultured and wild freshwater fish worldwide. CCB are gram-negative, yellow-pigmented bacteria that are ubiquitous in freshwater habitats. Outbreaks of the disease typically follow stressful events where the pathogen has a penchant for external tissues, such as skin and gill. As such, several surface disinfectants are used in combination with good management practices to prevent columnaris disease outbreaks. Vaccination against columnaris disease was practiced as early as the 1970’s. Since then, many different vaccine types have been under development, including killed, live-attenuated, recombinant, and micro- and nano-particle vaccines against columnaris disease. The development of an efficacious columnaris vaccine has been restricted partially due to a lack of understanding of the broad genetic diversity of CCB. There are phylogenetic and biochemical similarities that group CCB together, yet there are distinct genetic differences and host associations among CCB that resulted in their categorization into genomovars, then subsequently genetic groups. Recently, the phylogeny of F. columnare genetic groups was recognized as representing four distinct CCB species, including F. columnare, F. covae, F. davisii, and F. oreochromis. With the newfound knowledge of CCB species diversity and affinity for different host species, this has led to a resurgence of interest in developing columnaris vaccines that target appropriate host species.