Construction and sequencing of full-length cDNA clone of swine vesicular disease virus strain HK'1/70 / 病毒学报

By RACE, 2 overlapping cDNA fragments (3'PCR and 5'PCR fragments) covering the full genome of swine vesicular disease virus strain HK'1/70 were amplified from total RNA extracted from experimentally infected suckling mice. These fragments were cloned into pGEM-T Easy vector, respectively. 5'PCR fragment was digested by enzymes of Aat II and BssH II, and the Aat II-BssH II-digested 5'PCR fragment was obtained and cloned into the recombinant pGEM-T Easy vector containing 3'PCR fragment,the recombinant plasmid encoding full-length cDNA of SVDV HK'I/70 strain was then obtained and sequenced. The results showed that the complete genome of HK'1/70 was 7401 nucleotides (nts) long (excluding the poly (A) tract) which encodes a single polyprotein of 2185 amino acids, a 5'u ntranslating region (UTR) of 743 nts, a 3'UTR of 102 nts and a poly (A) tail at least 74 adenines. T' promoter was added at the 5'e nd of the full-length cDNA and an additional Pspl406I restriction site was added at the 3'e nd of poly (A) tail. The nucleotide and amino acid sequences were compared and phylogenetic analysis was used to examine the evolutionary relationships. The results showed that HK'1 /70 belonged to the second antigenic group. SVD virus was antigenically closely related to Coxsackie B5 virus, and located on the branches of CB5 evolutionary tree. Successful construction of full-length cDNA clone of SVDV HK'1/70 strain lays foundation for rescuing SVDV effectively and enables further research of SVDV on molecular level.

Eukaryonization of T7 RNA polymerase prokaryotic expression system and development of its couple expression system / 生物工程学报

To make transcription of the target gene be driven by T7 RNA polymerase (T7 RNAP) in the eukaryotic cells, and the transcripts be CAP-independent translated. Firstly, the T7 RNAP was introduced into eukaryotic cells by two methods: (1) the BHK-21 cells were contransfected by the plasmid expressing T7 RNAP and pIERS-EGFP-ET vector; (2) by transfection of the cell line stably expressing T7 RNAP. The internal ribosome entry site (IRES) element from FMDV was cloned into the downstream of the T7 promoter sequence of the prokaryotic expressing vector pET-40a-c (+), resulted in the plasmid would express the transcripts carrying the IERS element at its 5' end. The enhanced green fluorescent protein (EGFP) gene was cloned into the downstream of the IERS element, resulted in plasmid pIERS-EGFP-ET. Then, the two kinds of cells expressing T7 RANP were transfected by pIERS-EGFP-ET. The green fluorescence in the transfected cells was observed under a fluorescence microscope equipped with a video documentation system. And the expressional efficiency was analyzed with flow cytometry (FCM). The results show that the IRES element from FMDV has the role of initiating CAP-independent translation, and lay foundation for researching function of the element and interrelated proteins. It would be potential for expressing target gene by the T7 RNAP couple expression system.

Prediction of Secondary Structure and B Cell Epitope for Capsid Protein of SVDV / 中国生物工程杂志

The secondary structure of Capsid protein was predicted by the methods of Chou-Fasman,Garnier-Robson and Karplus-Schultz based on the sepuence of capsid protein gene of Swine Vesicular Disease Virus (SVDV) and hydrophilicity. Surface probility plot and antigenic index for capsid protein were obtained by the methods of Kyte-Doolittle, Emini and Jameson-wolf, respectively, Combining the results according to these methods, the B cell epitopes for capsid protein of SVDV were predicted. The results showed that there are much flexible region such as coil region and turn region in capsid protein of SVDV, there are more predominant B cell epitopes in VP1 than in VP2 and VP3. This study would be helpful for identification of B cell epitopes for capsid protein using experimental methods and research of reverse vaccine of SVDV.

Expression of recombinant plasmid pcDNA3.1/P12X3C with multi-genes of foot-and-mouth disease virus in BHK-21 cells / 生物工程学报

In order to obtain the gene P12X3C of Foot-and-Mouth Disease Virus (FMDV) that includes full length P1, 2A, 3C and a part of 2B, the site mutation strategy was used. After being digested by Kpn I and Xba I respectively, the gene P12X3C was cloned into the pcDNA3.1 (+) expression vector. The recombinant plasmid was checked by restriction enzyme analysis and nucleic acid sequencing, and then named pcDNA3.1/P12X3C. Further, BHK-21 cells was transfected with pcDNA3.1/P12X3C by using lipoid. The proteins of Foot-and-Mouth Disease Virus, which were expressed in BHK-21 cells, were confirmed by sandwich-ELISA and fluoroscopy. The result shows the gene P12X3C is cloned into eukaryotic expression plasmid, and the recombinant eukaryotic expression plasmid pcDNA3.1/P12X3C could express proteins of Foot-and-Mouth Disease Virus in BHK-21 cells, which have immunocompetence. This study demonstrates that delivery of a recombinant eukaryotic expression plasmid containing P12X3C coding regions results in the assembly of FMDV capsid structures, which will offer experimental base to DNA vaccine of FMDV.

Cloning of the major antigen region of E2 gene of hog cholera virus and expression in Escherichia coli / 生物工程学报

The major antigen region of E2 gene of Hog Cholera Prevalent Strain (Guangxi Yuling Strain) and Chinese Hog Cholera Lapinised Virus (C-strain) derived from hog and rabbit spleen tissue, was amplified by reverse transcription polymerase chain reaction(RT-PCR) and the nested Polymerase Chain Reaction (nPCR). After the amplified fragments were cloned into the expression vector pPROEX-HTb, the recombinant plasmids pPROEX-GXYL and pPROEX-C were obtained. The insert position, the size and the reading frame were right by PCR, restriction digestion and the sequence analysis. SDS-PAGE indicated that both of the reciepient germs transducted and induced by the recombinant plasmids pPROEX-GXYL and pPROEX-C could express the major antigen region of E2 gene. Western-blot indicated that the expressed antigen protein could be recognized by the positive serum of CSFV.

Study on the expression of E2 gene of classical swine fever virus in Pichia pastoris and the immunological activity of its expression product / 生物工程学报

E2 gene of classical swine fever virus (CSFV) was cloned into secretory pPIC9K Pichia pastoris expression vector. After being linearized by digestion, the vector was transformed into Pichia pastoris by electroporation to integrate with the genome, the transformants with high copies were screened by G418 and were induced to express with methonal. The results of SDS-PAGE and Western blot demonstrated that the supernatant of the induced P. pastoris culture contained protein E2. The results of the study on the immunological activity indicated that the protein E2 expressed in P. pastoris can elicit animal bodies to produce antibodies against protein E2.

Recent Advances on Reverse Genetics of Foot-and-mouth Disease Virus / 微生物学通报

Usage of reverse genetic techniques in the research area of the fundamental etiology of foot-and-mouth disease virus (FMDV), has resolved the issue about the function of viral gene of FMDV on genomic integer level. At present, a further recognition and apprehension for the molecular etiology of FMDV based on the development in reverse genetics was made. Combined with the research work in our labs, we reviewed international advances about the molecular pathogenic mechanism, the relationship be-tween virulence and variation in the genomes, influencing factors for the viral replication, and the develop-ment of new-type gene vaccine of FMD in this article, and propose the potential research aspects in reverse genetics of FMDV in the future.