| Human papillomavirus(HPV),a small DNA virus without membrane, which can survive in epithelia of human skin, genitals and respiratory tracts , is the etiological agent for many benign or malignant lesions. The structure of the virus genome is double strain DNA, and is composed of three gene regions, which are two protein encoding regions as well as one upstream modulating region and long control region (LCR). The two proteins encoding regions are E gene region (early gene region) and L gene region (late gene region) respectively. HPV was firstly isolated and characterized in 1950s, and now, more than 100 types have been characterized by means of sequencing and hybridization. According to the fatalness of carcinogenisis, all the types can be divided into two groups, which are low risk group (HPV6, 11, 13, 32, 42, 44, etc), high risk group (HPV16, 18, 45, 52, 56). It has already demonstrated that HPV has a close relationship with the occurrence and development of different kinds of benign and malignant tumors, among which, HPV16 is the main cause for cervical carcinoma in China, and ranks the second in the mortality of female malignant tumors. The capsid of HPV is mainly composed of L1 capsid protein, which contains important epitopes that can induce protective antibodies. Since HPV has the obligate epithalialphilic parasite, and it is hard to propagate in vitro or in animal, therefore, it is significant to construct and express L1 gene so that can be used in HPV diagnosis, prevention, as well as gene vaccine. In the present study, we searched and compared the similarity of L1 gene onthe internet, and found the conserved region. After that, we designed a pair of primers, and by PCR we obtained the HPV16 late gene L1 from cervical carcinoma in Xian. The PCR product was then inserted into pGEM-T vector. After sequencing, the 1256bp part of L1 gene, as well as amino acid sequence were obtained. It was found the 4 bases in the sequence was different with the reported original sequence, which demonstrated that area difference was possibly existed. The insert was then cloned into pBV220 vector to construct pBV220-L1 recombinant expression vector. After temperature induction, the molecule weight (MW)of the expressed product on the 10% SDS-PAGE was found to be the same with the predicted MW. Finally, the antigenic reactivity of the recombinant expressed product was assessed by Western-blotting, and it was shown that HPV16 gene could be expressed effectively in the prokaryotic expression system, and could react with both the commercialized anti papillomavirus antibody, which indicated that the expressed protein could be used to detect the antibody from HPV infected patients. On the other hand, the expressed product was amount to 11.5% of the total bacterial protein. Especially, the product is soluble, which means that the protein itself has the natural conformation, and can be purified directly by component isolation. This result can make it possible to provide the virus antigen with good immune reactivity, which lays foundation for the surveillance of epidemic situation, and finding of the infections as early as possible. Finally, the recombinant expressed product probably be used as vaccine, which can possibly become an efficient tumor treatment method.
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