Neural Transmission Mechanism Of Hemagglutinating Encephalomyelitis Virus Inoculated Into The Piglets By Oral Route

Porcine hemagglutinating encephalomyelitis (PHE), caused by hemagglutinating encephaomyelitis virus (HEV) has being increasing in recent years,but there was little newsreport about the research on the pathogenic mechanism.In order to study the neural transmission mechanism of Hemagglutinating encephalomyelitis virus, some colostrum-deprived pigs were inoculated with HEV strain 67N at the day of birth by the oral route,then they were sacrificed at 23 and 4 days postinfectionand tissues from stomachsmall intestine,heart,liver,spleen,lung,kidney,spinal cord and brain were gathered. Part of the tissues was stored in -80℃. Fluorescent quantitation RT-PCR method was used to evaluate the distribution of viral RNA in the tissues.and another part was soaked in formaldehyde,the method of immunohistochemical Staining (IHC) was applied to detceted the invading process of virus antigen.The results showed that pigs can be experimentally infected with HEV.and causes encephalomyelitis in suckling piglets. The result of IHC showed that virus antigen were first detected in the epithelial cell of small intestine and stomach nerve plexus on day 1,then virus antigen spreaded into sensory neuron cells in the dorsal horns of the thoracic vertebra spinal cord and lumbar vertebra spinal cord on day 2. On day 3, the virus was found in the neurons of cervical spinal cord,medulla oblongata and pons, antigen-postive cells were also spreaded into pyramidal neurons in cerebral cortex later, on day 4, purkinje cells were antigen-postive. The result of SYBR Green I real-time PCR showed that the virus load differed in different organ in the same day postinfection; and the dynamic changes differed in the same organ in different days postinfection. On day 1,the virus can be detected in small intestine and stomach.then the virus load went up in the tissues of brain and spinal cord.At last the virus can be detected widely in heart,liver.spleen,lung,kidney.In all.HEV spreaded along the neural ways after inoculated into the pigs orally.and can spreaded form spinal cord to brain.and mainly distributed in CNS, neuronophagia could be observed in cerebrum,On later period,hev transmited form CNS to the other organs,and the infected host became a virus carrier and virus diffuser.This research can provid some theoretical evidences on the pathogenic mechanism of HEV.