Expression of Coxsackievirus B3 coding gene in mammalian cells by recombinant vaccinia virus

The DNA fragments coding CVB3 capsid protein VP1 and VP2 were put under the control of 7.5k promoter in a vaccinia virus plasmid pGJP5, which were used to screen the recombinant vaccinia viruses VVP1 carrying CVB3 VP1 gene and the VVP2 carrying CVB3 VP2 gene through homology recombination respectively. The VP1 or VP2 protein was able to be observed in Vero cells infected with VVP1 or VVP2 by Western blot, though they were not secreted into the media. Then CVB3 capsid protein VP4/2/3/1 gene was inserted into the vaccinia virus expression plasmid pTM1 on the downstream side of the promoter T7, and the recombinant vaccinia virus VVP4/2/3/1 was constructed through homology recombination. The CVB3 VP4/2/3/1 ploypeptide in Vero cells was found on Western blot using the T7 RNA polymerase encoded by vT7. The results suggest that the mature expression of CVB3 capsid proteins has a strict requirement of the nonstructural region downstream. Thus, the entire coding region of CVB3 genome was introduced into a vaccinia virus expression plasmid pTM1 with the 5' untranslated region totally excluded, under the control of a T7 promoter. The transient expression in mammalian cells was studied using the T7 RNA polymerase encoded by vT7. The CVB3 proteins were able to be detected by ELISA both in the media and in the cells, and the proteins CVB3 VP1, VP2, VP3 in mature forms were all observed on Western blot using antisera against CVB3, CVB3 VP1 protein and CVB3 VP4/2/3 protein respectively. The work will provide basis for future study on the purification and immunological analysis of CVB proteins.