A PCR-based method to detect early mortality syndrome (EMS) of shrimp, developed by a Tainan-based research team led by Dr. Chu-Fang Lo, Dean of the College of Life Sciences at National Cheng Kung University (NCKU), in cooperation with Dr. Tim Flegel from Thailand, was announced by the university Monday at a press conference in Taipei.
Dr. Lo also announced that the primers and protocol were being put into the public domain, which will help shrimp researchers around the world control outbreaks of this disease.
Dr. Lo’s team cooperated with Dr. Flegel from Mahidol University for the last few months and developed a Polymerase Chain Reaction (PCR) method to detect EMS, also called acute hepatopancreatic necrosis disease (AHPND), a disease of cultured shrimp.
“We decided to release, free for public access, detailed information on the sequences and protocols from our research for a PCR-based detection method for bacteria causing AHPND, since there are currently severe, widespread outbreaks of this disease,” Dr. Lo said.
She also noted that the bacteria causing AHPND belong to Vibrio parahaemolyticus (VP), but they have unique plasmids not present in non-pathogenic VP.
Dr. Lo’s team used a whole-genome sequencing strategy to identify the plasmids as targets for detection and they designed two pairs of primers (AP1 and AP2) for the PCR method, a rapid test to detect virulent VP.
“If shrimp has virulent VP, the AP1 and AP2 primers will identify the VP and give a positive reaction,” explained Dr. Lo.
AHPND is causing high mortality in farm-raised shrimp in China, Vietnam, Thailand and Malaysia, according to Dr. Lo, who noted that the disease, first reported in 2009, now causes annual losses exceeding $1 billion.
These outbreaks were characterized as AHPND, in the absence of any accompanying sign of an infectious agent, during the early cultivation period of approximately 35 days.
The rapid PCR method to determine if shrimp is infected with the bacterium that causes AHPND will be highly beneficial to the shrimp-producing industry, Dr. Lo said.
Also, quick detection of AHPND could be very valuable for the aquaculture/seafood market, according to Dr. Lo.
She noted that release of this critical information will assist interested stakeholders to develop measures to reduce the risk of AHPND outbreaks.
