| Marek抯 Disease Virus(MDV) glycoprotein I(gI) genes were amplified from 648,CV1988,814 and GA strains respectively by Polymerase Chain Reaction(PCR). PCR products were cloned via pUC 18 vector at the restriction endoclease KpnI and J3amHI site. After sequencing, all gI genes were compared with that of GA strain. The result showed more than 99.2% homology between 4 different strains, and most of the mutants are between 200bp and 900bp. gI sequences were amplified from 166 to 1069bp of strain 648 with another pair of primers. PCR fragment was cloned to the downstream of GST gene according to the right Open Reading Frame(ORF) in pGEX-6P-lvector, and the recombinant was tranformed into host E.coli BL21 for expression. The expression of gI was indentified by SDS-PAGE and Western-blot, and found a 63kD in size as a fusion protein with GST. In order to get the maximum expression of gI, many factors are studied in detail, including temperature,time course and the concentration of IPTG. The growth curve of the recombinant bacteria was also established for optimal expression. The specific band was excised from the gel and injected into mice once a week for 5 times. The antisera was collected from the inununized mice and used for Indirect Fluorescent Assay(IFA) with Chicken Embryonic Firoblast(CEF) infected by RB1B,CV1988 and GA respectively. The positive stainings were found in the MDV plaques and localized on the cytomembrance of the infected cell. The result showed that the in vitro expressed protein of gI gene has some epitopes of MDV Another pair of primers was also synthesised for gI. It was cloned into pSV- ~ vector, with SV4O early promoter and enhancer,which can express foreign gene in mammalian cell. The recombinant plasmid for gene immunization was prepared in mass when purified and quantified, then it was injected into the leg muscles of mice directedly and with lipsome-mediated. IFA was used to indentified gI gene抯 expression, and the positive result was shown.
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