Scheme of construction of NYVAC-C-KC-ΔB19R.
To insert C7L and K1L back into the NYVAC genome, each gene plus a corresponding portion of the flanking regions was amplified by PCR. The two fragments were combined into one fragment using PCR. The entire cassette, containing C7L and K1L plus flanking regions homologous to the adjacent genes of the NYVAC genome (C8L and K2L), was inserted into NYVAC-C by in vivo recombination. To create NYVAC-C-KC-ΔB19R, the KC fragment was inserted into NYVAC-C-ΔB19R by the same method. IGR: Intergenic region.