Study On Pathology Of Porcine Hemagglutinating Encephalomyelitis

Porcine hemagglutinating encephalomyelitis is a hyperinfecting viraldisease which infect pedswine acutely,and caused by hemagglutinatingencephalomyelitis virus (HEV).Porcine hemagglutinating encephalomy-elitis can cause high death rate.Clinically,it take on two typus,one causeemesia and weakness mainly,the other induce functional disturbance ofcentral nervous system.Serology detection prove that swine infecting HEVis widespread,and may be cosmopolitan.In this study,we observed the process of HEV infecting PK15 cell in vitroby electron microscopy. After 12 hours of inoculation,we discovered thatH.E. virion adhere to cell envelope,and some virions intrused intoendochylema. After 24 hours, endochylema took on vacuolizationobviously, Mitochondria occurrenced intumesce, ground substance reduced,lophos was dim,even some of them have disappeard leaving vacuolus. After60 hours, virion pullulate on endoplasmic reticulum.We infected mice with HEV by several pathway, all mice occurrencedneurosis obviously. The group one onset at 48 hour after infected byinjecting in brain.The group infected by droping in nasal cavity ,hypodermic injecting at hind legs or intraperitoneal injection emergedneurosis at 70 hour,70 hour,100 hour in turns.Through pathohistology observation,we found that the best impairmentwas at central nervous system,which placed on apyogenous encephalitismainly.A neuron is surrounded with oligodendrocyte and microgliocytes.Besides, lung,kidney and other organ taken on diffenrence pathologicalchange.Cytopathic effect(CPE) mainly is vacuolization of micrangiumepithelial cell, apophysis of horizontal cell swelling. through theobservations of Corticocerebral ultramicrostructure of mouse.Theorganelles of glial cell and neuron caryon are vacuolization.some organellesare damaged,such as mitochondria swelling, ground substance decreasing,spine obscuring.Some neuron caryons are anomalism, lipofuscin-rich.Caryotin concentrates around nuclear membrane.A great quantity virionsare found in auxiliary fibers.some virions are reduplicating fromendoplasmic reticulum.The time of nerve symptom occurrence in young pigs is later thanmice,and symptom is less obviously in different routes of infection. Thesequence of nerve symptom occurrence in pigs is similar to mice in fourroutes of infection. Pathohistology observation is mainly suppurativeencephalitis.it displayed that pyramidal cells is triangular and cytoplasm isdeep-red color. Purkinje's cells are swelling,there are some vacuoluses inintracytoplasm, caryon is dissolved state. spinal neuron is degeneration andnecrosis. The neuron is surrounded with oligodendrocyte andmicrogliocytes. Otherwise, the glial nodule resulted from hyoerolasia andgarthering of mang glial cell can be seen in CNS. The results ofimmunohistochemistry display that pyramidal cells, Purkinje's cells andmyelonic neurons are positive reaction.Positive reaction are found inbrain,myelonic cervical segments after 24 hours intracerebral inoculation.There are no positive reactions in other sections of chorda spinalis. All ofthese explain that virions infect peripheral nerves of innoculate locationfirst,then spread to CNS.