Abstract: The porcine EMCV GXLC strain was used to infect 4-week-old healthy BALB/c mice to evaluate its pathogenicity. After infection, the clinical signs were observed; the pathological changes were analyzed and the ratios of heart weight to body weight were recorded; the viral loads in heart, brain, spleen and serum were determined; the protein loads of IL-1β and TNF-α in serum and the mRNA expression levels of IL-1β, TNF-α and IL-6 in heart, brain and spleen were detected. The results showed that the infected mice displayed obvious manifestations, and began to die on 4 days post-infection (DPI), reaching the death peak from 5 to 7 DPI. The heart and brain of the infected mice showed apparent gross lesions and histopathological changes, of which the ratios of heart weight to body weight and the histopathological scores were significantly increased. A large number of viruses were detected in brain, heart, spleen and serum from 1 DPI up to 14 DPI. The protein loads of IL-1β and TNF-α in serum from the infected mice were significantly increased and the mRNA expression levels of IL-1β, TNF-α and IL-6 in heart, brain and spleen were significant up-regulation, with closely positive correlation in time with obvious manifestations, severe pathological lesions and death peak of the infected mice. The results indicated that porcine EMCV GXLC strain was highly pathogenic to mice and the proinflammatory cytokines IL-1β, TNF-α and IL-6 played important roles in the pathogenesis of EMCV.

Key words: porcine encephalomyocarditis virus; pathogenicity; proinflammatory cytokine; mouse