Pathologic Studies in Piglets Naturally Infected with Porcine Reproductive and Respiratory Syndrome Virus

돼지 생식기 호흡기 증후군 바이러스 자연감염 예의 병리학적 연구

Porcine Reproductive and Respiratory Syndrome Virus infection (PRRSV) was confirmed by serology histopathology immunohistochemistry and bacteriologic examination in young pigs. Four suckling and six weaned piglets submitted from three different farms showed coughing sneezing labored rapid abdominal respiration lethargy and anorexia. Grossly apical and cardiac lung lobes appeared mottled with pale to dark tan discoloration. Submandibular and bronchial lymph nodes were tan and enlarged. All piglets were seropositive for PRRSV antibodies by the indirect immunofluorescent antibody(IFA) test. Microscopically lung lesions were characterized by hyperplasia and hypertrophy of type 2 pneumocytes infiltration of mononuclear cells in alveolar intersitium accumulation of necrotic debris in alveolar spaces accompanied by proliferation of alveolar multinucleated syncytial cells. Using immunohistochemical technique PRRSV antigens were demonstrated in alveolar macrophages and type 2 pneumocytes in histologic lung tissue sections. Also PRRSV antigens were detected in brain lymph nodes spleen and heart. Additionally piglets showed nonsuppurative meningoencephalitis mandibular necrotic lymphadenopathy splenic atrophy and myocardial necrosis.