Aranguren Caro Luis Fernando, Mai Hung N, Kanrar Siddhartha, Cruz-Flores Roberto, Dhar Arun K
Aquaculture Pathology Laboratory, School of Animal and Comparative Biomedical Sciences, University of Arizona, 1041 E. Lowell Street., Tucson, AZ 85721, USA.
Microorganisms. 2020 Oct 8;8(10):1549. doi: 10.3390/microorganisms8101549.
carrying binary toxin genes, AB, is one of the etiological agents causing acute hepatopancreatic necrosis disease (AHPND) in shrimp. This disease has emerged recently as a major threat to shrimp aquaculture worldwide. During a routine PCR screening of AHPND-causing strains, an isolate tested PCR positive for (R13) and another isolate tested positive for both the A and B (R14) genes. To evaluate the pathogenicity of these isolates, specific pathogen-free (SPF) were experimentally challenged. For both R13 and R14 isolates, the final survival rate was 100% at termination of the challenge, whereas the final survival with the AHPND-causing was 0%. The nucleotide sequence of the plasmid DNA carrying the binary toxin genes revealed that R13 contains a deletion of the entire gene whereas R14 contains the entire coding regions of both A and B genes. However, R14 possesses an insertion upstream of the A gene. In R14, mRNA for both A and B genes could be detected but no cognate proteins. This shows that the genome of AHPND-causing is highly plastic and, therefore, detection of the A and B genes alone by DNA-PCR is insufficient as a diagnostic test for AHPND.
携带二元毒素基因AB的副溶血性弧菌是导致对虾急性肝胰腺坏死病（AHPND）的病原体之一。这种疾病最近已成为全球对虾养殖业的主要威胁。在对引起AHPND的菌株进行常规PCR筛查期间，一个分离株对（R13）检测呈PCR阳性，另一个分离株对A和B（R14）基因均检测呈阳性。为了评估这些分离株的致病性，对特定无病原体（SPF）对虾进行了实验性攻毒。对于R13和R14分离株，攻毒结束时最终存活率均为100%，而感染引起AHPND的副溶血性弧菌的最终存活率为0%。携带二元毒素基因的质粒DNA的核苷酸序列显示，R13包含整个基因的缺失，而R14包含A和B基因的完整编码区。然而，R14在A基因上游有一个插入。在R14中，可以检测到A和B基因的mRNA，但没有相应的蛋白质。这表明引起AHPND的副溶血性弧菌的基因组具有高度可塑性，因此，仅通过DNA-PCR检测A和B基因作为AHPND的诊断测试是不够的。
