Location: Aquatic Animal Health ResearchTitle: Toxicity of recombinant PirA and PirB derived from Vibrio parahaemolyticus in shrimp
Submitted to: Microbial Pathogenesis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/9/2021
Publication Date: 4/29/2021
Citation: Zhang, D., Bader, T.J., Lange, M.D., Shoemaker, C.A., Beck, B.H. 2021. Toxicity of recombinant PirA and PirB derived from Vibrio parahaemolyticus in shrimp. Microbial Pathogenesis. 155:104886. https://doi.org/10.1016/j.micpath.2021.104886.
Interpretive Summary: Acute hepatopancreatic necrosis disease (AHPND), caused by emerging strains of V. parahaemolyticus, in shrimp aquaculture is of concern not only in Asia but also in Central and North America. Toxins secreted by V. parahaemolyticus, residing in shrimp, was the culprit of AHPND. Two proteins from the V. parahaemolyticus culture were identified and termed PirA and PirB. In this study, recombinant PirA and PirB (rPirA and rPirB) were produced heterologously, intra- and inter-molecular interaction between rPirA and rPirB was analyzed and the relative toxicity of rPirA and rPirB in shrimp was assessed. Results of this study were novel and provided new insight into toxic mechanism of PirA and PirB, which will be of interest to researchers and shrimp farmers.
Technical Abstract: Acute hepatopancreatic necrosis disease (AHPND), caused by emerging strains of Vibrio Parahaemolyticus, is of concern in shrimp aquaculture. Secreted proteins PirA and PirB, encoded by a plasmid harbored in V. parahaemolyticus, were determined to be the major virulence factors that induce AHPND. To better understand pathogenesis associated with PirA and PirB, recombinant proteins rPirA and rPirB were produced to evaluate their relative toxicities in shrimp. By challenging shrimp at concentration of 3 µM with reverse gavage method, rPirA and rPirB (approximately 0.4 and 1.5 µg per g of body weight, respectively) caused 27.8±7.8% and 33.3±13.6% mortality, respectively; combination of 3 µM rPirA and rPirB resulted in 88.9±7.9% mortality. Analysis of protein mobility in native gel revealed that rPirB was apparently in the form of monomer while rPirA was oligomerized as an octamer-like macromolecule, suggesting that inter- and intra-molecular interactions between rPirA and rPirB enhanced the toxic effect. An attempt to block or reduce rPirA activity with a putative receptor, N-acetyl-galactosamine, was unsuccessful, implying that remodeling analysis of PirA molecule, such as the octamer observed in this study, is necessary. Results of this study provided new insight into toxic mechanism of PirA and PirB and shall help design strategic antitoxin methods against AHPND in shrimp.