[Construction of poliovirus cDNA chimera with (NKNDD)n and (NANP)n]

Oligonucleotides encoding one copy of NKNDD, containing a P.f. B epitope NKND, and two copies of CSP repeated B epitope NANP were synthesized. After self-ligation, NKNDD and (NANP)2 were cloned into the intermediate vector pSKMM. Series of clones with different copies of NKNDD and NANP were identified. (NKNDD)n/MM with three, four, five, eight copies of NKNDD and (NANP)n/MM with four, six copies of NANP were chosen. Then (NKNDD)n and (NANP)n of these recombinants were recovered respectively and finally inserted into the N-Ag I site of poliovirus type I Mahoney strain full-length cDNA, which is contained in the expression plasmid pSV202H+. As using semi-quantitative hybridization in identifying tranformants, the procedure in our experiment for cloning different copies of NKNDD and NANP was greatly simplified.