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ARS Home » Northeast Area » Leetown, West Virginia » Cool and Cold Water Aquaculture Research » Research » Publications at this Location » Publication #416583
Research Project: Improving Salmonid Health through Breeding, Vaccination and Microbiome Modulation

Location: Cool and Cold Water Aquaculture Research

Title: Structural variation in Flavobacterium psychrophilum O-polysaccharide and host genetic resistance [abstract]

Author
item Wiens, Gregory
item CISAR, JOHN - US Department Of Agriculture (USDA)
item WANG, XIAOCONG - Huazhong Agricultural University
item SLOBODA, SEADA - Minnesota State University, Mankato
item ZHU, YONGTAO - Xi'An Jiaotong-Liverpool University
item CAIN, KENNETH - Manchester Research Station, Northwest Fisheries Science Center, Noaa-Fisheries
item WOODS, ROBERT - Complex Carbohydrate Research Center
item Leeds, Timothy

Submitted to: American Fishery Society (Fish Health Section) Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 6/28/2024
Publication Date: 7/31/2024
Citation: Wiens, G.D., Cisar, J.O., Wang, X., Sloboda, S., Zhu, Y., Cain, K.D., Woods, R.J., Leeds, T.D. 2024. Structural variation in Flavobacterium psychrophilum O-polysaccharide and host genetic resistance [abstract]. American Fishery Society (Fish Health Section) Proceedings. No. 4.

Interpretive Summary: N/A

Technical Abstract: At the U.S. National Center for Cool and Cold Water Aquaculture, we have selected a line of rainbow trout with increased innate resistance against bacterial cold water disease (BCWD) caused by Flavobacterium psychrophilum (Fp). Our selection program utilized Fp strain CSF259-93 and the specificity of host genetic resistance against strain variants is incompletely understood. A major locus of variation between Fp strains is within a cluster of genes involved in the biosynthesis of O-polysaccharide (O-PS), a component of lipopolysaccharide (LPS). The aims of this research were to 1) improve understanding of genetic and structural variation in Fp O-PS, and 2) evaluate whether this variation impacts host genetic resistance. A mouse monoclonal antibody (mAb FL100A) previously prepared against Fp strain CSF259-93 (serotype Th), was examined for binding to LPS of this strain and Fp strain 950106-1/1 (serotype Fd). The corresponding O-PS of these strains are formed by identical trisaccharide repeats that are joined by wzy2-dependent a(1–2) linkages in Fp CSF259-93 while they are joined by wzy1-dependent ß(1–3) linkages in Fp 950106-1/1. mAb FL100A reacted strongly with Fp CSF259-93 O-PS and LPS but weakly or not at all with Fp 950106-1/1 LPS and O-PS. mAb FL100A also labelled cell surface blebs on the former but not the latter strain. Molecular dynamic simulations of each O-PS suggests that Fp CSF259-93 O-PS formed a stable well-defined compact helix, while the unreactive Fp 950106-1/1 O-PS adopted a flexible extended linear conformation. Using a novel genetic manipulation system, the wzy2 gene in Fp CSF259-93 was replaced with wzy1, and as predicted, mAb FL100A no longer labelled cell surface blebs. We challenged three genetic lines of rainbow trout (resistant, control and susceptible) with both wildtype Fp CSF259-93 and the wzy2/wzy1-swapped mutant. The relative host resistance of the three genetic lines was not altered when challenged with the wzy2/wzy1-swapped mutant. These results suggest that while the structural variation in the O-PS affects mAb FL100A binding and the humoral response, innate genetic resistance is not impacted by variation in O-PS.