MOLECULAR CHARACTERISATION AND PHYLOGENETIC ANALYSIS OF PORCINE CIRCOVIRUS-2 ISOLATED FROM INFECTED PIGS IN THE SOUTHERN REGION OF INDIA

Abstract

ABSTRACT: Porcine circovirus-associated diseases (PCVAD) caused by Porcine Circo Virus-2 (PCV-2) is an emerging viral disease with serious effects on animal health, food security, and the swine industry. In this study, samples were collected from the PCV-2 suspected swine carcasses presented to the Department of Veterinary Pathology, CVAS, Mannuthy, for necropsy. Out of 39 suspected samples, seven were positive for PCV-2 by polymerase chain reaction targeting the ORF-2 gene, which yielded an amplicon size of 481 bp. The blast analysis sequences of the present isolates showed more than 98 percent homology with other parts of India and foreign isolates. The genotypic analysis revealed different PCV-2 genotypes, viz., PCV2d (57 percent), PCV-2b (29 percent), and PCV-2h (14 percent), and clusters 13, 11, and 18, respectively, for the first time in Kerala. The microscopic examination revealed lymphoid depletion in the spleen, soft palate tonsils, various lymph nodes, ileal Peyer's patches (IPP), and jejunal Peyer's patches (JPP). There were occasional botryoid inclusion bodies in mucosa-associated lymphoid tissues (MALT) with congestion in various lymph nodes. Based on history and clinical signs, gross, histopathological, and PCR results, and sequence data, the presence of PCV-2-associated systemic disease was confirmed in this study. Altogether, these findings are helpful in further understanding the pathogenesis of PCV-2, which would help to evolve better strategies for improved disease control and prevention in pigs. Future investigations on the pathogenesis of these new genetic variants of isolates obtained in the present study are required for a better understanding of the pathogenesis of the disease.

Keywords

• pcv-2
• pcr
• phylogenetic analysis
• histopathology