Đặc điểm sinh hóa và di truyền của chủng vibrio parahaemolyticus gây bệnh hoại tử gan thận cho cá mú nuôi tại Cát Bà, Hải Phòng

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Ngôn ngữ: vie

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Thông tin xuất bản: Tạp chí Khoa học kỹ thuật Thú y, 2019

Mô tả vật lý: tr.62

Bộ sưu tập: Báo, Tạp chí

ID: 312781

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Vi khuẩn Vibrio parahaemolyticus gây bệnh hoại tử gan thận cho nhiều loài cá biển có giá trị kinh tế cao. Từ những mẫu cá mú mắc bệnh thu thập ở Cát Bà, Hải Phòng, đã phân lập được 6 mẫu vi khuẩn có hình thái, đặc điểm sinh hóa đặc trưng cho chủng V. parahaemolyticus. 6 mẫu vi khuẩn này đều có tính kháng với 5 loại kháng sinh nghiên cứu, đặc biệt có tính kháng cao với ampicillin. Tỷ lệ sống sót của cá mú chấm cam (Epinephelus coioides) sau 14 ngày gây nhiễm với 6 mẫu vi khuẩn là từ 2,2% đến 18,89% ở liều 100 μl/con, 107 CFU/ml. Khi phân tích sự có mặt của các gen độc tố haemolysin, đã phát hiện được sự có mặt của 2 gen độc tố toxR và tlh trên cả 6 mẫu vi khuẩn. Gen tdh và trh không được phát hiện trong hệ gen của 6 mẫu vi khuẩn phân lập. Đã khuếch đại được trình tự gen toxR và tlh hoàn chỉnh với kích thước gen tương ứng lần lượt là 879 bp và 1254 bp với hai cặp mồi toxR2- toxR4 và tlh1-tlh3 tự thiết kế. Kết quả nghiên cứu này là cơ sở cho những nghiên cứu về đột biến gen, về cấu trúc không gian, cơ chế gây bệnh của những protein được mã hóa từ 2 gen độc tố này.Vibrio parahaemolyticus bacteria causes hepatic kidney necrosis disease in several marine fish species having highly economic value. From a number of the diseased groupers collecting in Cat Ba, Hai Phong, 6 bacterial strains having typically morphological and biochemical characteristicsof V. parahaemolyticus species were identified. All these 6 bacterial strains resisted to 5 studied antibiotics, particularly resisted strongly to ampicillin. The survival rate of Epinephelus coioides (orange spot grouper) after 14 days of experimental infection with 6 bacterial strains was 2.2% to 18.89% at dose of 100 μl/fish, 107 CFU/ml. The result of analyzing the presence of haemolysin virulent genes showed that there were 2 toxR and tlh genes in all 6 isolated strains. The tdh and trh genes were not detected in genome of 6 isolated strains. The full sequences of toxR and tlh genes were amplified with the corresponding sizes were 879 bp and 1254 bp with 2 self-design primers (toxR2- toxR4 and tlh1-tlh3). This studied result is basis for the further researches on gene mutation, space structure, pathogen mechanisms of proteins coding from 2 these toxicity genes.

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