jmbReview The Epitope Recognized by Monoclonal Antibody 2 B 6 in the B / C Domains of Classical Swine Fever Virus Glycoprotein E 2 Affects Viral Binding to Hyperimmune Sera and Replication

Classical swine fever virus (CSFV), a member of the genus Pestivirus within the family Flaviviridae, is the causative agent of classical swine fever that is highly contagious and causes significant economic losses to the swine industry [1, 15, 19]. CSFV is an enveloped RNA virus with the genome size of approximately 12.3 kb, flanked by 5 ́and 3 ́nontranslated regions (NTRs). The viral genome encodes a polyprotein of 3,898 amino acids that is processed by cellular and viral proteases to generate four structural (C, Erns, E1, and E2) and eight nonstructural proteins (Npro, P7, NS2, NS3, NS4A, NS4B, NS5A, and NS5B)[14, 29]. Phylogenetic analysis of the 5’-NTR, E2, or NS5B divides CSFV strains into three groups with 11 subgroups [22, 26]. Typical historical strains, including the vaccine strains, belong to group 1, whereas currently circulating strains and those that have caused infections since the 1980s form group 2, and those distributed in Taiwan and some other regions belong to group 3 [8, 23, 25, 33]. Several reports indicate that subgroup 2.1 strains have branched away from the vaccine C-strain and become dominant in China [4, 17, 31]. E2 is the major viral envelope protein of high immunogenicity that induces neutralizing antibodies and confers protection against infection. Four major antigenic domains A, B, C, and D, all located in the N-terminal region of E2, have been identified using a panel of monoclonal Received: Jul;y 28, 2014 Revised: September 23, 2014 Accepted: October 29, 2014