1. Department of Aquatic Animal Medicine; College of Fisheries; Huazhong Agricultural University; Wuhan 430070 China
2. Freshwater Aquaculture Collaborative Innovation Center of Hubei Province; Wuhan 430070 China
3. Key Lab of Freshwater Animal Breeding; Ministry of Agriculture; Wuhan 430070 China
4. State Key Laboratory of Agricultural Microbiology; Huazhong Agricultural University; Wuhan Hubei 430070 China
5. Department of Public Health Sciences; University of Hawaii; Manoa HI 96822 USA
6. Public Laboratory of Electron Microscopy; Huazhong Agricultural University; Wuhan Hubei 430070 China