Đánh giá khả năng gây bệnh của Vibrio sp. phân lập từ tôm thẻ bị bệnh hoại tử gan tụy cấp tính tại Ninh Thuận

Abstract

     The disease was first seen in China in 2009, before it spread to Viet Nam in 2010 Acute hepatopancreatic necrosis disease (AHPND), also called early mortality syndrome (EMS) in shrimp was first seen in China in 2009, before it spread to Viet Nam and cause serial death of shrimp in Ninh Thuan in 2010. In this study, we isolated 56 strains of Vibrio sp. from 30 samples of white shrimp were infected AHPND in shrimp ponds in Ninh Thuan. From the result of LD₅₀ testing showed 12 strains of Vibrio sp. has high lethal virulence in which Vibrio sp. NT2.5 has the highest virulence (LD₅₀ = 8.98×10³ CFU / mL). The shrimp disease in this experiment were tested by histological methods. In PCR technique, by using specific primers to detect PirAvp and PirBvp toxin genes, 6 Vibrio sp. strains were identified that contain the toxin genes PirAvp and PirBvp, NT 2.5; NT2.8; NH5.3c; NH8.4 and NT4.5 have PirBvp gene, NT6a has PirAvp gene. The biochemical methods for identification of 6 strains was performed, it homologous over 80% with Vibrio parahaemolyticus. The highest virulent NT2.5 was identified by PCR method, sequencing based on the 16S rDNA region, showed that NT2.5 was identified as Vibrio parahaemolyticus.

Keywords: Acute hepatopancreatic necrosis disease (AHPND), white shrimp, Vibrio parahaemolyticus, PirAvp, PirBvp