First identification, molecular characterization, and pathogenicity assessment of Lactococcus garvieae isolated from cultured pompano in Taiwan

Sandip Neupane; Shreesha Rao; Wei-Xiao Yan; Pei-Chi Wang; Shih-Chu Chen

doi:10.1111/jfd.13848

First identification, molecular characterization, and pathogenicity assessment of Lactococcus garvieae isolated from cultured pompano in Taiwan

J Fish Dis. 2023 Nov;46(11):1295-1309. doi: 10.1111/jfd.13848. Epub 2023 Aug 14.

Authors

Sandip Neupane¹, Shreesha Rao², Wei-Xiao Yan¹, Pei-Chi Wang^{1

2

3

4}, Shih-Chu Chen^{1

2

3

4

5}

Affiliations

¹ International Degree Program of Ornamental Fish Technology and Aquatic Animal Health, International College, National Pingtung University of Science and Technology, Pingtung, Taiwan.
² Department of Veterinary Medicine, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan.
³ Research Centre for Fish Vaccine and Diseases, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan.
⁴ Southern Taiwan Fish Diseases Research Centre, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan.
⁵ Research Centre for Animal Biologics, National Pingtung University of Science and Technology, Pingtung, Taiwan.

PMID: 37578999
DOI: 10.1111/jfd.13848

Abstract

Lactococcosis, caused by Lactococcus garvieae, is an acute hemorrhagic septicemia in fish recorded in marine and freshwater aquaculture during the summer months. In 2020-2021, several sea cage Pompano farms recorded sudden fish mortality events. Based on the results of phenotypic and biochemical tests, L. garvieae was predicted to be the cause. PCR with L. garvieae specific primers (pLG1 and pLG2) targeting the 16S rRNA region further confirmed the etiological agent as L. garvieae after amplifying an 1100 base pairs (bp) product. Furthermore, the 16S rRNA sequences of the two representative strains (AOD109-196-2B and AOD110-215-2B) shared 99.81% identity with L. garvieae (GenBank accession number: MT597707.1). The genetic profiles of the strains were classified using pulsed-field gel electrophoresis after digestion with SmaI and ApaI, which clustered our strains under the same pulsotype. Multiplex PCR targeting the capsule gene cluster and serotype-specific PCR collectively showed that the strains were non-capsulated; thus, they belonged to serotype I. An experimental infection was designed to fulfil Koch's postulates by infecting healthy Pompano with case-driven L. garvieae strains (AOD109-196-2B and AOD110-215-2B) with a cumulative mortality of 70%. Overall, L. garvieae infection in Pompano emphasizes the need for better monitoring and control procedures in aquaculture settings.

Keywords: Lactococcus garvieae; PFGE; capsule gene cluster; golden pompano; pathogenicity; serotype.

Grants and funding

Council of Agriculture