Construction and identification of infectious molecular clone of foot-and-mouth disease virus strain O/CHINA/99 / 病毒学报

Nine primers were designed for the full-length genome of O/CHINA/99 and each sequence fragment was obtained by RT-PCR, and cloned into pOK12 vecter, the full-length genome cDNA clone of O/CHINA/99 was identified by restriction enzymes digestion, PCR, and the whole genome sequencing. The results showed that the O/CHINA/99 whole genome was formed with the length of 8200 nt. The nucleotide sequence of the full-length cDNA shared 99.1% homology with its prototype. RNA synthesized in vitro by means of a bacteriophage T7 promter inserted in front of the cDNA led to the production of infectious particle upon transfection of BHK-21 cell using lipofectamine reagent, as shown by cytopathic effects. The rescued virus had high pathogenicity in mice by endermic infection too. All the results showed that an infectious molecular clone was successfully constructed and rescued virus could be obtained.

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.