Pathological and immunological characteristics of piglets infected experimentally with a HP-PRRSV TJ strain

Abstract

Background: Porcine reproductive and respiratory syndrome (PRRS) remains a major threat to swine industry all over the world. The aim of this study was to investigate the mechanism of pathogenesis and immune responses caused by a highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV). Results: All piglets experimentally infected with a HP-PRRSV TJ strain virus developed typical clinical signs of PRRS. The percentages of CD3+, CD4+, and CD8+ lymphocytes significantly decreased in the infected group as compared to the uninfected control animals (p < 0.01). Total WBC dropped in the infected animals during the experiment. The level of ELISA antibody against PRRSV increased in 7-10 days after infection and then started to decline. Pathological observations demonstrated various degree lesions, bleeding and necrosis in the lungs of the infected piglets. Conclusions: These results clearly indicated that HP-PRRSV TJ strain infection would activate host humoral immune response at the early period post infection and cause severe pathological damages on lungs and inhibit cellular immune response after infection.