Correlation of viral load with lesion severity in field pigs affected with porcine circovirus type 2

Abstract

Porcine circovirus type 2 (PCV2) is an important infection factor causing post weaning multisystemic wasting syndrome (PMWS). The amount of PCV2 viral load may mainly give rise to clinical symptom and pathological lesion of PMWS. In order to investigate the relationship between PCV2 viral load and the lesion severity of lymph tissues, and search further for some clues of pathologic diagnosis of PMWS, thirty pig cases affected with PCV2 and aged 30～90 days old were collected from swine farms and their lymph tissues were treated by quantitative Real Time PCR, immunohistochemistry (IHC) and histopathology examination. Four various groups were classified according to their evaluation scores for lesion severity, and it is shown that the higher the score for pathological lesion of lymph tissues, the more there is viral load in tonsil. Especially, the amount of PCV2 DNA in group one was 1/1000 lower than other three groups. It is supposed that group one is considered as subclinical case and the other three groups as clinical PMWS cases. Furthermore, it is likely presumed whether PCV2 infection is subclinical or clinical PMWS case can be helpfully diagnosed by these criteria.