One of the most prevalent diseases affecting vannamei shrimp is Acute Hepatopancreatic Necrosis Disease (AHPND), also known as Early Mortality Syndrome (EMS).

This disease was first identified in China in 2009 and has since spread across Southeast Asia, including Thailand, Vietnam, the Philippines, and Indonesia. AHPND causes significant losses in the shrimp farming industry due to its high mortality rates. The disease is caused by the bacterium Vibrio parahaemolyticus, which specifically carries the pirA and pirB genes (commonly referred to as pirvpA and pirvpB).

Let’s take a closer look at the pirA and pirB genes in Vibrio parahaemolyticus.

V. parahaemolyticus Contains pirA and pirB Genes

The pirA and pirB genes are located on specific plasmids within the Vibrio parahaemolyticus bacterium and serve as the primary culprits behind Acute Hepatopancreatic Necrosis Disease (AHPND) in vannamei shrimp. These genes are responsible for producing toxins that damage the hepatopancreas, a critical organ for metabolism and digestion in shrimp.

The pirA and pirB genes reside on a virulence plasmid within Vibrio parahaemolyticus. Their products are binary toxin proteins that work together: pirA acts as the subunit that facilitates toxin binding to target cells, while pirB serves as the active subunit that enters the cell and causes damage.

These toxins attack the hepatopancreas in two ways:
 

1. Disrupting the cell membrane, causing leakage.
2. Inducing apoptosis (cell death) in hepatopancreatic cells.

Infections caused by pirA and pirB genes trigger various symptoms, such as:
 

• Reduced shrimp appetite
• Pale and shrunken hepatopancreas
• High mortality rates within a short period (70–100% at DOC 30)

Addressing pirA and pirB, the Cause of AHPND/EMS

Detecting pirA and pirB genes is essential for identifying the presence of virulent Vibrio parahaemolyticus in shrimp farms. PCR methods can be used to detect these genes in bacteria. If the pirA and pirB genes are found, the shrimp are highly likely to be infected with AHPND/EMS.

Some measures to combat AHPND/EMS include:
 

• Water quality management: To reduce environmental stress that triggers infections.
• Probiotics: To increase positive microorganisms in the water and suppress Vibrio dominance.
• Disinfectants: To minimize bacterial contamination in the water.
• Functional feed: To boost shrimp immunity against infections.
• Strict biosecurity: To prevent the entry of pathogens from external sources, especially through inlet and outlet points.
• Shrimp health checks: To monitor shrimp quality and resistance to diseases.

Overcome pirA and pirB with ShrimpProtect from CeKolam

Protect your shrimp farms from EMS/AHPND threats with ShrimpProtect, an advanced detection solution. This technology can identify the pirA and pirB target genes in less than 35 minutes. Using Fenrir Master Mix and fluorescence probe technology, ShrimpProtect provides fast, accurate, and reliable detection for various types of samples in shrimp health assessments.

With effective early detection, you can take preventive steps promptly to maintain shrimp health and enhance your farm's productivity.

Don’t wait until it’s too late—optimize your shrimp farming now!
Contact us at 0882-1877-4777 for more information.

 

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References

1. Nainggolan RKS, Yuhana M, Sukenda, Sariati WNE. 2020. Detection of Vibrio parahaemolyticus Using the pirA Gene Marker in Vannamei Shrimp (Litopenaeus vannamei) with Real-Time PCR. Journal of Aquaculture Research. 15(2):111–119.
2. Kurnianingtyas FNR, Saputra I, Purbayu MA. 2021. Strategic Steps for Controlling the Potential AHPND Outbreak in Shrimp Farming in Indonesia. Quarantamina. 3(1):1–13.
3. Joshi J, Srisala J, Truong V, Chen IT, Nuangsaeng B, Suthienkul O, Lo CF, Flegel T, Sritunyalucksana K, Thitamadee S. 2014. Variation in Vibrio parahaemolyticus Isolates from a Single Thai Shrimp Farm Experiencing an Outbreak of Acute Hepatopancreatic Necrosis Disease (AHPND). Aquaculture. 428–429.
4. JALA Tech - Acute Hepatopancreatic Necrosis Disease
5. Trobos Aqua - AHPND: Know the Causes, Prevent the Spread