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Appl Environ Microbiol. 2017 Jun 16;83(13). pii: e00737-17. doi: 10.1128/AEM.00737-17. Print 2017 Jul 1.

Acute Hepatopancreatic Necrosis Disease-Causing Vibrio parahaemolyticus Strains Maintain an Antibacterial Type VI Secretion System with Versatile Effector Repertoires.

Li P1, Kinch LN2, Ray A1,2, Dalia AB3,4,5, Cong Q6,7, Nunan LM8, Camilli A3,4, Grishin NV2,6,7, Salomon D9,10, Orth K9,2,6.

Author information

1
Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
2
Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
3
Department of Molecular Biology & Microbiology, Tufts University School of Medicine, Boston, Massachusetts, USA.
4
Howard Hughes Medical Institute, Tufts University School of Medicine, Boston, Massachusetts, USA.
5
Department of Biology, Indiana University, Bloomington, Indiana, USA.
6
Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
7
Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
8
School of Animal & Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona, USA.
9
Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas, USA dorsalomon@mail.tau.ac.il kim.orth@utsouthwestern.edu.
10
Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.

Abstract

Acute hepatopancreatic necrosis disease (AHPND) is a newly emerging shrimp disease that has severely damaged the global shrimp industry. AHPND is caused by toxic strains of Vibrio parahaemolyticus that have acquired a "selfish plasmid" encoding the deadly binary toxins PirAvp/PirBvp To better understand the repertoire of virulence factors in AHPND-causing V. parahaemolyticus, we conducted a comparative analysis using the genome sequences of the clinical strain RIMD2210633 and of environmental non-AHPND and toxic AHPND isolates of V. parahaemolyticus Interestingly, we found that all of the AHPND strains, but none of the non-AHPND strains, harbor the antibacterial type VI secretion system 1 (T6SS1), which we previously identified and characterized in the clinical isolate RIMD2210633. This finding suggests that the acquisition of this T6SS might confer to AHPND-causing V. parahaemolyticus a fitness advantage over competing bacteria and facilitate shrimp infection. Additionally, we found highly dynamic effector loci in the T6SS1 of AHPND-causing strains, leading to diverse effector repertoires. Our discovery provides novel insights into AHPND-causing pathogens and reveals a potential target for disease control.IMPORTANCE Acute hepatopancreatic necrosis disease (AHPND) is a serious disease that has caused severe damage and significant financial losses to the global shrimp industry. To better understand and prevent this shrimp disease, it is essential to thoroughly characterize its causative agent, Vibrio parahaemolyticus Although the plasmid-encoded binary toxins PirAvp/PirBvp have been shown to be the primary cause of AHPND, it remains unknown whether other virulent factors are commonly present in V. parahaemolyticus and might play important roles during shrimp infection. Here, we analyzed the genome sequences of clinical, non-AHPND, and AHPND strains to characterize their repertoires of key virulence determinants. Our studies reveal that an antibacterial type VI secretion system is associated with the AHPND strains and differentiates them from non-AHPND strains, similar to what was seen with the PirA/PirB toxins. We propose that T6SS1 provides a selective advantage during shrimp infections.

KEYWORDS:

AHPND; MIX effectors; T3SS; T6SS; Vibrio; Vibrio parahaemolyticus; shrimp; type III secretion system; type VI secretion system

PMID:
28432099
PMCID:
PMC5478980
DOI:
10.1128/AEM.00737-17
[Indexed for MEDLINE]
Free PMC Article

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