Diagnosis of the infectious pancreatic necrosis virus (IPNV) by nested PCR in adult trouts.

STEELHEAD trout; RAINBOW trout; TROUT; NECROSIS; CELL culture; PYLORUS

The isolation of the infectious pancreatic necrosis virus (IPNV) in cell culture is currently the main diagnostic method. Although it is a reliable method, it is expensive, and the results take three weeks. This study aimed to establish and evaluate the use of a nested PCR (nPCR) for the rapid diagnosis of the IPNV, decreasing the diagnosis time and increasing its sensitivity. Therefore, two pairs of primers were designed based on Mexican sequences. The first pair (RT-PCR) amplified a 682 bp product, and the second pair (nPCR) 229 bp of the VP2 gene. Subsequently, 70 rainbow trout fry (Oncorhynchus mykiss) were infected with the virulent strain MEX3-CSM-05 at a dose of 1X105.8 TCID50/0.02 ml. From each organism, the kidney, spleen, pyloric caeca, liver, intestine, and gills were collected. To evaluate the tests, a total of 26 clinically healthy adult trouts from commercial farms in the State of Mexico were used. The detection frequency of the IPNV using RT-PCR was 87.1% in gills, 61.4% in liver, 61.4% in pyloric caeca, 58.6% in kidney, 35.7% in the intestine, and 32.9% in the spleen (P<0.05). RT-PCR negative samples were positive in the nPCR. Similarly, samples from the wild trout organs were positive. In conclusion, the RTPCR was less sensitive than the nPCR, which showed a sensitivity of 100%. Therefore, nPCR is the best option for a reliable diagnosis of the IPNV in infected and sick fish. [ABSTRACT FROM AUTHOR]

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