TopSPEC® Aeromonas hydrophila qPCR KIT (SQF-102)

About TopSPEC® Aeromonas hydrophila qPCR KIT

Pangasius (Pangasianodon hypophthalmus) is one of the main freshwater aquaculture species, serving as an important source of food and exportable seafood in Vietnam and other tropical countries such as Thailand, Cambodia, Myanmar, Indonesia, Malaysia, Bangladesh, India, and the Philippines. However, the shift from extensive to intensive farming has reduced available culture areas and increased environmental pollution, creating favorable conditions for the emergence of infectious diseases in Pangasius.

Hemorrhagic disease (HD), also known as Red Spot Disease, is a common and damaging disease in Pangasius. It spreads rapidly, causing mortality rates of about 30–70% in adult fish and up to 100% in fry. In Vietnam, hemorrhagic disease occurs year-round, with outbreaks most common during the transition between the rainy and dry seasons. The disease spreads from infected fish to healthy ones within the same pond.Clinical signs of the disease can be divided into stages. In the early stage, symptoms include loss of appetite, lethargy, surfacing behavior, darkened skin, and reduced mucus secretion. In the second stage, hemorrhagic spots appear on the body, fin bases, around the mouth, eyes, and anus. Ulcers are often accompanied by fungal and parasitic infections. In the final stage, the eyes become bulging, inflammation occurs around the eye sockets, mucus is lost, the anus becomes inflamed and hemorrhagic, the abdomen is swollen, and fins become frayed or torn.Pathological findings include gas-filled intestines, necrosis of the liver and kidneys, abdominal hemorrhage, pale liver, enlarged gallbladder, swollen kidneys, and internal bleeding. In acute cases, upon dissection, a large amount of reddish fluid mixed with blood is found in the abdominal cavity, with severe internal bleeding leading to high mortality within a short period.

The causative agent of the disease has been identified as Aeromonas spp., primarily caused by Aeromonas hydrophila (AH) is the causative agent, first isolated from salmon in the United States in 1979 and first reported in Vietnam in 1993. It is a heterotrophic, rod-shaped, Gram-negative bacterium belonging to the family Aeromonadaceae isolated from diseased striped catfish in the Mekong Delta revealed that this bacterium is commonly found in freshwater and brackish environments of tropical and warm regions. A. hydrophila can survive under both aerobic and anaerobic conditions and is capable of degrading proteins such as gelatin and hemoglobin. In nutrient broth, after 24 hours of incubation, the medium becomes turbid with a thin, viscous film forming on the surface, which sinks after several days. On agar plates, colonies appear circular, slightly raised at the edges, smooth, moist, and cream-colored.A. hydrophila exhibits strong antibiotic resistance, and to date, no effective vaccine has been developed for disease prevention in fish due to its high genetic variability, making it difficult to identify the key virulence factors of this species. However, a study by Phuong et al., 2023 on A. hydrophila strains isolated from striped catfish showed that Aeromonas spp., were isolated from hemorrhagic striped catfish samples in Vietnam, showing that in addition to the A.hydrophila (both non-virulent and highly virulent strains), the research group also found that Aeromonas dhakensis and it was proven to exhibit higher virulence compared to A.hydrophila. A. dhakensis which were previously identified as Aeromonas hydrophila strains SSU, however, sequencing and comparison of the gyrB gene revealed differences from the strains A.hydrophila of other strains, leading to their classification as a new species. Therefore, the detection of the causative agent Aeromonas spp., of hemorrhagic disease in Pangasius hypophthalmus should include the detection of both A.hydrophila và A. dhakensis

TopSPEC® Aeromonas hydrophila qPCR Kit is a diagnostic tool designed to detect the presence of the Aeromonas hydrophila and differentiate between highly virulent Aeromonas hydrophila (vAh) and Aeromonas dhakensis causing hemorrhagic disease in Pangasius (tra fish), detected using Real-time PCR technology.

TopSPEC® Aeromonas hydrophila qPCR Kit

Highlights

• Simple procedure
• Optimize the PCR time to 1.5 hours.
• Various input sample types
• High specificity and sensitivity

Specification

Recommended extraction kit

TopPURE® Genomic DNA Extraction Kit

TopPURE® Maga Genomic DNA/RNA Extraction Kit 

Read more: Instructional Video for Qualitative Real-time PCR Kit