In order to identify the neutralizing epitope of the porcine epidemic diarrhea virus (PEDV), the spike protein region that is presumed to contain the virus-neutralizing epitope was determined. This was based on the sequence information for the neutralizing epi-tope of the transmissible gastroenteritis virus (TGEV). A recombinant protein that corresponds to the spike region of TGEV was produced, and polyclonal antis-era were generated using the recombinant protein. It was discovered that polyclonal antisera significantly inhibited plaque formation by PEDV, suggesting that this region of the spike protein contains the epitope(s) that is capable of inducing PEDV-neutralizing anti-bodies. In addition, the region that corresponds to the neutralizing epitope of TGEV may also be involved in neutralizing PEDV, although the two viruses are sero-logically quite distinct. Finally, the amino acid se-quences that are deduced from the genes for the de-termined-neutralizing epitope were highly homologous among the PEDV strains that were isolated from dif-ferent geographical areas, which suggests conservation of the antigen gene.

Keywords: PEDV, TGEV.