Susceptibility of Soiny Mullet (Liza
Haematocheila) to
Streptococcus Dysgalactiae and Physiological Response to
Formalin Inactivated S.Dysgalactiae
Z.T. Qi1,2,§,*, J. Y. Tian3,§,
Q.H Zhang2, R. Shao2, M, Qiu1,2,
Z.S. Wang1,2, Q. J. Wei1 and J.T. Huang1
1Key Laboratory of
Aquaculture and Ecology of Coastal Pool in Jiangsu Province,
Department of Ocean Technology, Yancheng Institute of
Technology, Yancheng 224051, China; 2College
of Chemical and Biological Engineering, Yancheng Institute of
Technology, Yancheng 224051, China; 3National
Oceanographic Center, Qingdao 266071, China
*Corresponding author: qizhitao@ycit.edu.cn
Abstract
Streptococcosis caused great lost in intensive
aquaculture in China
every year. The Streptococcus dysgalactiae,
one of the main pathogen of streptococcosis in cultured fish in
China, caused high mortality of Soiny Mullet (Liza
hematocheila) with typical symptom after intraperitoneal injection. The
semi-lethal dose of S. dysgalactiae to
mullet was 5.4×106 CFU. The antigen against
S. dysgalactiae was prepared by formalin inactivated
S. dysgalactiae. After intraperitoneal
injection of the antigen, the survival rate of fish infected with
S. dysgalactiae was significantly
increased. At the same time, the splenic and hepatic lysozymes of
mullet were also significantly increased. The splenic and hepatic ALP were
decreased from 1 day to 3 day and back to normal level at 7 days after vaccine
injection. All these data strongly suggested that the formalin-inactivated
S. dysgalactiae is an effective
strategy to protect mullet against S.
dysgalactiae.