Design and construction of African swine fever virus chimeras incorporating foreign viral epitopes

In the present work we have studied the feasibility of introducing foreign epitopes into the African swine fever virus (ASFV) particle by genetic mani pulation of the virus. For this purpose, we developed specific transfer vec tors containing the gene encoding for the highly antigenic structural ASFV protein p54 in which foreign sequences were introduced. DNA sequences encod ing continuous linear epitopes, the antigenic site A from foot-and-mouth di sease virus (FMDV) VP1 protein and the DA3 antigenic determinant from trans missible gastroenteritis coronavirus (TGEV) nucleoprotein N, were separatel y cloned into the p54 gene, in a region encoding a non-essential domain of the protein. Chimeric p54 genes were inserted by homologous recombination i nto the thymidine kinase (TK) locus of ASFV genome. The resulting recombina nt viruses efficiently expressed both chimeric proteins under transcription al control of,the P54 promoter, and the chimeric gene products were recogni zed by antibodies to both p54 and foreign epitopes. The modified p54 protei ns were also found in the viral particles and complemented the function of the wild-type p54, since deletion of the p54 gene from recombinant viruses did not affected virus replication in Vero cells. This work demonstrates fo r the first time the feasibility of incorporating foreign amino acid sequen ces (up to 18 residues) into a protein component of the ASFV particle witho ut affecting virus viability.