| Avian encephalomyelitis virus (AEV) is a picornavirus with a predilection for the central nervous system and other parenchymous organs of chickens that is transmited by the oral-faecal route.The virus may be spread by the vertical and horizontalroutes, and because of its great stability,contaminated areas may remain infectious for long periods.The egg-adapted Van Roekel strain is highly neurotropic and does not grow efficiently in the enteric tract of the chicken,and the field isolates of AEV is usually enterotropic .Despite this.the virion polypeptides of both naturally-occurring strains and the Van Roekel strain are antigenically identical. In young chickens AEV induces paralysis, ataxia and muscular dystrophy, while in older chickens, infection is usually subclinical,resulting in a decline in egg production and hatchability.Infectivity was shown to remain unaffected by chloroform,low pH, pepsin, trypsin and deoxyribonuclease.Magnesium cations were shown to stabilise preparations of the virus against heat inactivation.The buoyant density of virions are 1.31g/ml.The diameter of the virion was estimated to be 22 to 30nm.The AEV can be adapted to grow in chicken embryo.The inability of AEV to grow effeciently in most cell cultures.In 1932,outbreaks of a disease causing neurotropic dysfunction in young chickens in the New England region of the USA in 1930 were first reported by Jones.Over the next decade,outbreaks of the disease were reported in Europe, Canadajapan and Australia.In 1980s,The disease was transmited into China. AEV has long been recognised as the aetidaogical agent of one of the most significant disease of poultry.Despite its importance,relatively little progress had been made towards an understanding of its basic biology and pathogenesis.The purpose of this study was to learn the sequence and structure of the AEV by technology of the molecular biology.to reveal the relation between genome features and function. The research consist of four parts.The first part is multiplication,purification and electron microscope examination of the avian encephalomyelitis virus.A 1:5 dilution of isolate-NH937 of AEV and control group of PBS were inoculated to susceptible 6-day-old chickensembryos.respectively.After incubation for 10 days,the urinay vesicle liquid was collected.Making a comparison the size of the chickens embryos between the test group and the control group,the results showed that the size of the control group is bigger than that of the test group.Purified virions were examined under the electron microscope,the result revealed that there are a lot of virions and the AEV-NH937 was multiplicated in embryos.The second part was seguence analysis of the genome of the AEV-NH937.Nine pairs of primers were designed according to published Calnek vaccine strain of AEV. RT-PCR was used to amplify the cDNA of the genome .These cDNA fragments were cloned into the plasmid pUCm-T.The result indicated that the seguence of the genome was obtained. The genome of AEV-NH937 composed of 7055 nucleotides, potentially encodes a polyprotein of 2134 amino acids. The genome of AEV-NH937 has 94.3% nucleotides identity with the Calnek vaccine strain of AEV. it was firstly reported in China.The third partrthe capsid protein VP| gene was expressed.810 bp fragment was inserted into vector pGEX-4Tl,and then transformed into E.coli BL21. SDS-PAGE analysis showed that the expressed product is a 53KD fusion protein aftor induction with IPTG. The expressed product was lysised with supersonic wave and purified by SDS-PAGE.ELISA analysis revealed that the antigenicity of the VPi protein has been detected. The forth part-detection of AEV-NH937 strain by In Situ Hybridization(1SH)-Probe was labelled with digoxigenin(Dig).Then the probe hybrid with 5d,10d,and 20d postinfection brain tissue of chicken.The results of the ISH showed that the positive signal was found in 3 cases,while control group was negative.there has been a reasonable correlatien between this method and other detection test.
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