MOLECULAR AND PATHOLOGICAL STUDIES OF POST-WEANING MULTI-SYSTEMIC WASTING SYNDROME AMONG PIGLETS IN KERALA, INDIA

Post weaning multi systemic wasting syndrome (PMWS) is an economically important porcine viral associated diseases caused by porcine circovirus 2(PCV2) in weaned piglets worldwide. Recently, the presence of PCV2 was reported in pig population of Kerala. But, PMWS and its association with other pathogens were not explored. Therefore, this study was designed with the objective of screening of 40 piglets for PMWS with concurrent screening for porcine reproductive and respiratory syndrome virus (PRRSV) and porcine parvo virus (PPV). Swine carcasses presented for post-mortem examination with a history of respiratory and reproductive problems collected from February, 2018 to February, 2019 from different parts of Kerala formed the samples for this study. The samples were initially screened with PCR followed by gross, histopathology and immunohistochemical characterisation. Gross lesions observed were mainly generalised icterus in the subcutaneous tissues, non-collapsed lungs, hydrothorax, enlarged bronchial lymph nodes, hepatomegaly with randomly distributed areas of white foci and yellowish colour kidneys. Histopathological lesions revealed bronchointerstitial pneumonia, lymphoid depletion in the germinal centre of the follicles with multifocal areas of granulomatous inflammation in the lymph nodes, lymphoid depletion in the peri-arteriolar lymphoid sheath of the spleen and interstitial nephritis of the kidney. Further, immunohistochemistry (IHC) demonstrated PCV2 antigensmainly in the spleen and lymph nodes. The present study reports three out of four positive PCV2 cases which fulfilled the diagnostic requirements of PMWS. However, PMWS cases were negative for both PRRSV and PPV. Therefore, the present study identified the immunosuppressive nature of PMWS among pig population of Kerala.