Effect On The Expression Of ATF3 And MX1 In Brain Of Mice Infected With Hemagglutinating Encephalomyelitis Virus

Porcine Hemagglutinating Encephalomyelitis is an acute and highly contagious infectious disease of piglets which is caused by the Porcine Hemagglutinating Encephalomyelitis Virus (PHEV), which predominantly affects 1 to 3 weeks lactating piglets. Clinically, piglets appear vomiting, exhaustion and/or significant neurological symptoms as the main feature and the mortality rate 20% to 100%, it will bring huge economic losses to the aquaculture industry. PHEV has neurotropic spread mainly by the site of infection through the peripheral nerves to the central nervous system, making brain exhibit a pathological non-suppurative encephalomyelitisdamage. MX protein is an anti-viral protein by I interferon (IFNα/β) inducing the host cell to produce a broad-spectrum antiviral effect. ATF3 is the member of activating transcription factor family, a key regulatory factor of transcription regulation, apoptosis, cell division and survival, which is closely related to the virus replication. Previous studies showed that, after the cerebral cortex of mice and neuroblastoma N2a infected PHEV, ATF3 and MX1 all showed differences in gene expression, but it’s not clear that whether the two genes different expression had a direct relationship with the viral infection, or the level of expression of the two genes correlatedwith the PHEVreplication level. Therefore, this study intends to measure the expression levels of ATF3, MX1 and PHEV in the brain of mice infected by thePorcine Hemagglutinating Encephalomyelitis Virus. To study the relationship between ATF3, MX1 expression and PHEV replication level of the brain at different stages after the mice infected the PHEV.Methods:We built the model of mice being acutely infected by PHEV, with 0.1mL of PHEV (103TCID5o/0.1mL) intracranial inoculation infecting healthy 5-week-old female Kunmingmice, making the mice all dead in the fifth day. In this study,30 healthy female 5-week-old Kunming mice were randomly divided into the virus and control groups, each group 15. The virus group was injected with PHEV 0.1mL, and the control group was injected with the same dose of PBS. After the infection, respectively 1～5d mice were clinically observed, at the same time,3 mice were sacrificed each day. The brain tissues were taken out respectively, a part of it frozen in liquid nitrogen, and then the fluorescent quantitative PCR was measured; the other was fixed in formalin solution to prepare H.E. staining and immunohistochemistryproduction.The results showed that, there were no abnormalities of mice diet and mental state on the 1-2 days mice after inoculation; The 3rd day mice after inoculation, showed significant neurological symptoms, such as arched, two forelegs lifted up and down as "Play the piano" The 5th day mice after inoculation, paralyzed, convulsive and dead; The inoculation group had no abnormal reactions. After autopsy, the brain of mice was observed, with large hyperemia and edema. Histopatho logical observation revealed that the brain of the mice in the poison group was a typical non purulent encephalitis, such as neuronal condensation, necrosis, microglia increased, satellite phenomenon and "vascular cover" formation. By Real-time PCR, The expression levels of ATF3 and MX1 in the brain of the mice infected by the virus were higher than that of the PHEV, and were positively correlated, significantly (p<0.01). Comparison of PHEV and ATF3 gene expression in brain of mice with different time of infection. We found that, in the control group, the mice of 1～4days, the virus content and ATF3 gene expression were significantly different (p<0.05). Immunohistochemical results showed that the brain ATF3, MX1 and PHEV cytoplasm were stained brown positive signal after the mice infection. And the expression of ATF3 protein, MX1 protein and PHEV increased in the brain.