Classical swine fever virus(CSFV)is the causative agent of classical swine fever(CSF),a highly contagious,economically important viral disease in many countries.The Erns and E2 envelope glycoproteins are responsible for the binding to and entry into the host cell by CSFV.To date,only one cellular receptor,heparan sulfate(HS),has been identified as being involved in CSFV attachment.