Screening and identification of the SARS-CoV N protein epitopes

The epitopes of SARS-CoV were screened from a 12-mer phage display random peptide library using anti- SARS-CoV horse polyclonal antibodies of as a target. The phage clones enriched in biopannings were sequenced. Two consensus sequences were obtained, DXXDP and TXTLL, which had close identity to the 341-345 as and 392-396 aa of SARA-CoV N protein sequences,respectively. The phage clones with consensus sequences and the N protein were both recognized and bound by the antibodies in a competitive-inhibition ELISA test. The consensus sequence peptides were cloned and displayed on the bacterial flagellin. Balb/c mice were vaccinated using the reconstruted bacteria and the collected serum was shown to speccifically combined with SARS-CoV N protein. This confirmed that DXXDP and TXTLL are two continuous epitopes of SARS-CoV N protein.