Philippine Standard Time

DOST-PCAARRD-funded study explores the causes of early mortalities in shrimp

Academic exchange at Academia Sinica (T6SS project team with members of Dr. Erh-Min Lai's lab

Shrimp, an economically-important commodity in the country, can be infected with Vibrio spp., which causes Acute Hepatopancreatic Necrosis Disease (AHPND) that can lead to mortalities as it spreads rapidly. Giant tiger prawn and white leg shrimp can be affected by the disease that can cause 100% mortality within 20-30 days of stocking.

To potentially inhibit the growth of Vibrio spp., a study, “Role of Type VI Secretion System during shrimp infection of Vibrio spp.-causing AHPND,” will use Type VI Secretion System, or T6SS and study the pathogenicity of other virulent factors present during shrimp infection.

T6SS is a nanomachine used for gram-negative bacteria to inhibit the growth and kill them by injecting toxins into the eukaryotic cells of target bacteria.

In recent bioinformatics analysis, only AHPNDVP strains encode T6SS while non-AHPND-causing V. parahaemolyticus does not have T6SS. Other AHPND-causing Vibrio spp. were identified from affected shrimp populations including V. harveyi, V. owensii, V. campbellii and V. punensis.

This project is a three-year research study (2022-2024) implemented by the Department of Agriculture – National Fisheries Research Development Institute (DA-NFRDI) under the 2021 Manila Economic and Cultural Office – Taipei Economic and Cultural Office (MECO-TECO) Joint Research Program funded by the Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development of the Department of Science and Technology (DOST-PCAARRD), Ministry of Science and Technology and Academia Sinica (AS), a premier fisheries research institution in Taiwan. MECO-TECO promotes scientific collaboration and academic exchange between Taiwan and the Philippines.

Results and potential impact of the study

Project staff conducting the experiments at the NFRDI laboratory (Image credit: DA-NFRDI)

Whole genome sequencing of V. parahaemolyticus PH1339 (AHPND-causing) and V. parahaemolyticus 1273 (non AHPND-causing) has been done. Initial results revealed that the V. parahaemolyticus strains from the Philippines may be genetically divergent from the strains that are in the current database. Moreover, sequence analysis revealed that V. campbellii, V. owensii, and V. harveyi encode two T6SS gene clusters, namely T6SS1 and T6SS2. Most importantly, most of these strains have a conserved T6SS1 core components and encode different putative effectors/toxins that may be involved in AHPND pathogenicity in shrimp.

The findings of this study could provide new insights and reveal potential target for disease control that might lead to the development of diagnostics, effective therapeutics, and vaccines to mitigate AHPND or other Vibrio-causing diseases.

The project is led by Dr. Mary Nia M. Santos, head of the Aquatic Animal Health Section, Aquaculture Research and Development Division, NFRDI; Dr. Erh-Min Lai and Dr. Chih-Horng Huo,research fellow and principal investigators at the Institute of Plant and Microbial Biology, AS.