Cytotoxicity of Vibrio parahaemolyticus AHPND toxin on shrimp hemocytes, a newly identified target tissue, involves binding of toxin to aminopeptidase N1 receptor

Waruntorn Luangtrakul; Pakpoom Boonchuen; Phattarunda Jaree; Ramya Kumar; Han-Ching Wang; Kunlaya Somboonwiwat

doi:10.1371/journal.ppat.1009463

Cytotoxicity of Vibrio parahaemolyticus AHPND toxin on shrimp hemocytes, a newly identified target tissue, involves binding of toxin to aminopeptidase N1 receptor

PLoS Pathog. 2021 Mar 26;17(3):e1009463. doi: 10.1371/journal.ppat.1009463. eCollection 2021 Mar.

Authors

Waruntorn Luangtrakul¹, Pakpoom Boonchuen^{1

2}, Phattarunda Jaree³, Ramya Kumar^{4

5}, Han-Ching Wang^{4

5}, Kunlaya Somboonwiwat¹

Affiliations

¹ Center of Excellence for Molecular Biology and Genomics of Shrimp, Department of Biochemistry, Faculty of Science, Chulalongkorn University, Bangkok, Thailand.
² School of Biotechnology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima, Thailand.
³ Center of Applied Shrimp Research and Innovation, Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand.
⁴ Department of Biotechnology and Bioindustry Sciences, College of Biosciences and Biotechnology, National Cheng Kung University, Tainan, Taiwan.
⁵ International Center for the Scientific Development of Shrimp Aquaculture, National Cheng Kung University, Tainan, Taiwan.

Abstract

Acute hepatopancreatic necrosis disease (AHPND) caused by PirABVP-producing strain of Vibrio parahaemolyticus, VPAHPND, has seriously impacted the shrimp production. Although the VPAHPND toxin is known as the VPAHPND virulence factor, a receptor that mediates its action has not been identified. An in-house transcriptome of Litopenaeus vannamei hemocytes allows us to identify two proteins from the aminopeptidase N family, LvAPN1 and LvAPN2, the proteins of which in insect are known to be receptors for Cry toxin. The membrane-bound APN, LvAPN1, was characterized to determine if it was a VPAHPND toxin receptor. The increased expression of LvAPN1 was found in hemocytes, stomach, and hepatopancreas after the shrimp were challenged with either VPAHPND or the partially purified VPAHPND toxin. LvAPN1 knockdown reduced the mortality, histopathological signs of AHPND in the hepatopancreas, and the number of virulent VPAHPND bacteria in the stomach after VPAHPND toxin challenge. In addition, LvAPN1 silencing prevented the toxin from causing severe damage to the hemocytes and sustained both the total hemocyte count (THC) and the percentage of living hemocytes. We found that the rLvAPN1 directly bound to both rPirAVP and rPirBVP toxins, supporting the notion that silencing of LvAPN1 prevented the VPAHPND toxin from passing through the cell membrane of hemocytes. We concluded that the LvAPN1 was involved in AHPND pathogenesis and acted as a VPAHPND toxin receptor mediating the toxin penetration into hemocytes. Besides, this was the first report on the toxic effect of VPAHPND toxin on hemocytes other than the known target tissues, hepatopancreas and stomach.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Bacterial Toxins / metabolism*
Hemocytes / metabolism*
Penaeidae / microbiology*
Vibrio Infections / metabolism*
Vibrio parahaemolyticus / pathogenicity*
Virulence / physiology

Substances

Bacterial Toxins

Grants and funding

This research was funded by Chulalongkorn University under the Ratchadaphisek Somphot Endowment (CU_GR_62_79_23_30) to KS and the Thailand Research Fund (International Research Network Scholar (No. IRN61W0001)) to KS. Student fellowships to WL from the 100th Anniversary Chulalongkorn University Fund for Doctoral Scholarship, the 90th Anniversary of Chulalongkorn University Fund, and the Overseas Research Experience Scholarship for Graduate Students from the Graduate School, Chulalongkorn University, are greatly appreciated. Additional support from the Ministry of Science and Technology, Taiwan (MOST-108-2314-B-006-096-MY3) to HC is also acknowledged. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.