Nghiên cứu độc lực của vi khuẩn Streptococcus agalactiae 015-RIA1 trên cá rô phi vằn chọn giống sinh trưởng nhanh thế hệ G2

Nghiên cứu được thực hiện nhằm xác định độc lực của vi khuẩn S. agalactiae 015-RIA1 trên cá rô phi vằn (Oreochromis niloticus) chọn giống sinh trưởng nhanh thế hệ thứ 2. Kết quả này sẽ được ứng dụng để phát triển chỉ thị phân tử liên quan đến khả năng kháng bệnh trên cá rô phi vằn chọn giống sinh trưởng nhanh. | TNU Journal of Science and Technology 228 13 274 - 281 THE VIRULENCE OF 015-RIA1 Streptococcus agalactiae ON NILE TILAPIA OF 2nd GENERATION GROWTH PERFORMANCE SELECTION Pham Hong Nhat1 Vu Thi Huyen1 Truong Thi My Hanh1 Nguyen Thi Hanh1 Ngo Phu Thoa2 Pham Anh Tuan3 Phan Thi Van1 1Research Institute for Aquaculture RIA1 2Vietnam National University of Agriculture VNUA 3Vietnam Fisheries Society VINAFIS ARTICLE INFO ABSTRACT Received 10 7 2023 This study was carried out to determine the Streptococcus agalactiae 015-RIA1 virulence on Nile tilapia Oreochromis niloticus of 2nd Revised 30 8 2023 generation growth performance selection. The virulence of bacteria was Published 13 9 2023 assessed through the Serotype virulence genes and the lethal dose of 50 LD50 . The results showed that the 015-RIA1strain characterized KEYWORDS as serotype Ia contained 12 virulence genes belonging to 3 clusters involved in the process of adhesions invasions and immune evasions. Tilapia This proves that 015-RIA1 strain is as virulence strain. The LD50 value Virulent genes was 2 2 x 106 cfu ml after 21 days of infection challenge. After 18 Serotype hours of infection mortality started and infected fish indicated clinical signs such as lethargy hemorrhage on the skin and base of fins LD50 exophthalmos eye protrusion and cloudy eyes. Bacterial isolation Streptococcus agalactiae from infected fish samples after infection was caused by S. agalactiae. The highest cumulative mortality rate was after 8 days of infection challenge. Meanwhile in the control group uninfected fish showing no clinical signs no death and no S. agalactiae was isolated. These results will be applied to develop molecular markers relationship with disease resistance in Nile tilapia of growth performance selection. NGHIÊN CỨU ĐỘC LỰC CỦA VI KHUẨN Streptococcus agalactiae 015-RIA1 TRÊN CÁ RÔ PHI VẰN CHỌN GIỐNG SINH TRƯỞNG NHANH THẾ HỆ G2 Phạm Hồng Nhật1 Vũ Thị Huyền1 Trương Thị Mỹ Hạnh1 Nguyễn Thị Hạnh1 Ngô Phú .