Aquaculture Canada and WAS North America 2022

August 15 - 18, 2022

St Johns, Newfoundland, Canada

CHARACTERIZATION AND COMPARATIVE GENOMIC ANALYSIS OF Vibrio anguillarum REVEALS SIGNATURE PATHWAYS OF THE O-ANTIGEN BIOSYNTHESIS IN SEROTYPES O1, O2 AND O3

Vimbai I. Machimbirike*, Ignacio Vasquez, Trung Cao, Joy Chukwu-Osazuwa, Oluwatoyin Onireti, Maryam Ghasemieshkaftaki, Ha Thanh Dong, Pongsak Khunrae, Triwit Rattanarojpong, Marije Booman, Simon Jones, Manuel Soto-Davila, Brian Dixon, Javier Santander.

Department of Ocean Sciences, Memorial University of Newfoundland, 0 Marine Lab Road, St. John’s, A1C 5S7, St. John’s, NL, Canada. imachimbirik@mun.ca

 



Vibrio anguillarum serotypes O1, O2 and O3 are the most frequent pathogens of fish world-wide. Genetics differences between serotype that could give light on the evolution of this marine pathogen are unknown. Here, we fully sequenced and phenotypically characterized a V. anguillarum O1 isolated from a winter Steelhead trout (Oncorhynchus mykiss irideus) in British Colombia, Canada and compared it to a serotype O2 isolate. V. anguillarum O1 strain caused vibriosis and 100% mortality in naïve lumpfish (Cyclopterus lumpus). Its genome contains 2 chromosomes (3,13 Mb and 1,03 Mb) and 2 typical serotype O1 pJM1-like plasmids (65,573 and 76,959 bp). Furthermore, V. anguillarum O1 displayed resistance to Colistin sulphate which differs from serotype O2 that could be attributed to the presence of the ugd gene in serotype O1.

omparative genomic analysis among the serotypes showed that genetic heterogeneity in the O-antigen biosynthesis gene cluster is characterized by gene absence and presence of unique genes. Serotype O1 is composed of 22 O-antigen biosynthesis genes (rfbA-H, galU, ugd, galE, gae, wecA-C, wecE, manA-B, glmU, wbpM, wbpV, wbpI), whilst serotype O2 is composed of 13 O-antigen biosynthesis genes (galU, galE, manA-B, wecB-C, glmU, wbpE, wbpI, wbpM, wbpO, wbplA, wlbD) and serotype O3 is composed of 13 O-antigen biosynthesis genes (galU, galE, rfbA-B, manA-B, wecB-C, glmU, wbpM, wbpO, wbpP, wbpV)

Serotype O1 utilizes the Wzx/Wzy-dependent pathway for O-antigen translocation and polymerization, while the serotypes O2 and O3 employs an alternative pathway. Insertion sequences play a role in the evolution of the O-antigen gene cluster via recombination events. This heterogeneity possibly results in differences in immune evasion mechanisms employed by the respective serotypes. Our work will contribute towards understanding pathogenesis of V. anguillarum, impacting disease control and vaccine development against the pathogen.

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