Page 89 - 《渔业研究》2025年第5期

630 渔 业 研 究 第 47 卷

Identification and analysis of key virulence factors in highly pathogenic
Vibrio coralliilyticus infecting shellfish

2,3
2,3
1,2
LI Peijun ，ZHANG Xiang ，NI Jinglei ，HUANG Bowen ，WANG Chongming ，
2
2,3
1*
GUO Yongjun ，BAI Changming 2,3*
(1. Tianjin Key Laboratory of Aqua-ecology and Aquaculture, College of Fisheries, Tianjin Agricultural University,
Tianjin 300384, China;
2. National Key Laboratory of Marine Aquaculture Breeding and Sustainable Production, Functional Laboratory of Marine Fisheries
Science and Food Production Processes, Key Laboratory of Aquatic Animal Disease Control of Ministry of Agriculture and Rural
Affairs, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China;
3. Shandong Center of Technology Innovation for Oyster Seed Industry, Qingdao 266105, China)

Abstract: [Background] In recent years, frequent disease outbreaks during the shellfish nursery phase in
China have caused substantial economic losses. Vibriosis is one of the primary pathogenic diseases involved,
with Vibrio corallilyticus identified as a major pathogen in shellfish hatcheries in northern China, capable of
causing acute mortality in bivalve larvae. [Objective] This study systematically investigates the physiological
and biochemical characteristics of pathogenic strains, the proteomic profile and enzymatic activities of their ex-
tracellular products (ECPs), aiming to identify key virulence factors that influence the pathogenicity of V. coral-
lilyticus toward shellfish larvae. The findings are expected to provide a scientific basis for establishing an integ-
rated prevention and control system for vibriosis during the shellfish nursery period in China. [Methods] Three
highly pathogenic strains of V. corallilyticus (RSH02, RSH05, RSH08) isolated from shellfish hatcheries in
Shandong and Jiangsu provinces were used in the study. The strains were cultured to the logarithmic growth
phase, and growth curves were determined. ECPs from the three highly pathogenic strains and one low-patho-
genicity strain were prepared simultaneously using the cellophane plate method. The molecular profiles of ECPs
from different strains were separated by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-
PAGE) based on molecular sieving effects. Characteristic protein bands of the highly pathogenic strains were
selected, and their extracellular protein compositions were identified using mass spectrometry. Finally, protease
activity, hemolysin activity, and siderophore production were assessed using specific agar media (protease as-
say medium, hemolysin identification medium, and chrome azurol s medium). [Results] All three highly patho-
genic strains exhibited similar growth curves, with a logarithmic growth phase between 8 and 24 hours, and
demonstrated strong proteolytic, hemolytic, and siderophore activities. The ECPs of RSH02, RSH05, and
RSH08 were enriched with highly active aminopeptidase, peptidase M4, and neutral metalloproteinase, respect-
ively. [Conclusion] Although the three highly pathogenic V. corallilyticus strains shared similar growth charac-
teristics, their ECP compositions differed significantly, suggesting that different strains may exert high patho-
genicity and tissue-lytic capability through the secretion of specific virulence factors, such as aminopeptidase,
peptidase M4, and metalloproteinase. This finding provides new insights into the pathogenic mechanisms of V.
corallilyticus.
Key words: shellfish hatchery stage; Vibrio coralliilyticus; extracellular products; protein profiles