Localization of antigenic sites of the E2 glycoprotein of transmissible gastroenteritis coronavirus

Abstract

Four antigenic sites of the E2 glycoprotein of transmissible gastroenteritis virus were defined by competitive radioimmunoassays ofmonoclonal antibodies (MAbs). Here, we describe the localization of these sites by testing the antigenicity of protein fragments and prokaryotic expression products of E2 gene fragments, and by sequencing of MAb-resistant (mar) mutants. Partial proteolysis of purified E2 protein allowed the isolation of a 28K fragment recognized by both site A-and site C-specific MAbs. An antiserum against this fragment bound to a synthetic peptide containing residues 1 to 18 and to an expression product containing residues 1 to 325. The same expression product was recognized by site C-specific MAbs. These data indicate that residues within the sequence 1 to 325 contribute to site C and possibly also to site A. Sequencing of mar mutants that escaped neutralization by site A-specific MAbs indicated that residues 538 and 543 also belong to site A. The binding of site-specific MAbs to expression products led directly to the localization of sites B and D, between residues 1 to 325 and 379 to 529, respectively. The first 37 % of the polypeptide chain of E2 appears to be more immunogenic than the rest of the sequence.

Location of antigenic sites defined by neutralizing monoclonal antibodies on the S1 avian infectious bronchitis virus glycopolypeptide

“…We were not able to confirm our result by using other techniques, because our neutralizing MAbs did not bind to relevant synthetic peptides in a Pepscan analysis (Geysen et al, 1984) or to prokaryotic expression products of S1 gene fragments (Kusters et al, 1989a). This failure is caused by conformation dependence of the antigenic sites Lenstra et al, 1990). The amino acids composing the epitopes of some MAbs are widely separated on the sequence map (Fig.…”

“…The antigenic structure and location of neutralization epitopes have been reported for two other coronaviruses: transmissible gastroenteritis virus (TGEV) (Correa et al, 1990;Delmas et al, 1990) and mouse hepatitis virus (MHV) (Parker et al, 1989). It is difficult to compare neutralization epitopes of these coronaviruses directly with those of IBV, however, since the sequence identity of IBV S1 and the N-terminal part of S of the other viruses is low (de Groot et al, 1987b).…”

“…The antigenic site S1-F was found to be located within a region of 47 amino acids of the S1 subunit C terminus, whereas S2-G was located within a region of 20 amino acids of the $2 subunit N terminus (Kusters et al, 1989a). However, antigenicity of epitopes expressed by fusion proteins and by synthetic peptides depends on the primary structure only (conformation-independent) and not on the native structure of the protein antigen (conformation-dependent) (Lenstra et al, 1990). As the MAbs that define the antigenic sites S1-A to SI-E did not react with fusion proteins, these antigenic sites were considered to be conformation-dependent.…”

Characterization of the IgA and subclass IgG responses to neutralizing epitopes after infection of pregnant sows with the transmissible gastroenteritis virus or the antigenically related porcine respiratory coronavirus

“…The previously characterized TGEV-specific monoclonal antibodies (MAbs; Correa et al, 1988Correa et al, , 1990Jimrnez et al, 1986) were kindly provided by Dr L. Enjuanes (Centro Nacional de Biotecnolog~a, CSIC, Madrid, Spain). The porcir~e Ig class-specific MAbs, anti-lgA, antiIgG 1 and anti-lgG e were kindly provided by Dr C. R. Stokes (Bristol University, Bristol, U.K.).…”

Bovine coronavirus spike glycoprotein: localization of an immunodominant region at the amino-terminal end of S2

“…Conformation-independent determinants have been found on the N-terminal part of transmissible gastroenteritis virus (TGEV) (Delmas et al, 1990;Correa et al, 1990) and the MHV S1 subunits (Routledge et al, 1991), but the MHV and infectious bronchitis virus $2 subunits have also been reported to bear conserved linear determinants recognized by neutralizing MAbs (Luytjes et al, 1989;Talbot et al, 1988;Routledge et al, 1991 ;Kusters et al, 1990). Two of these B cell epitopes have been tested for their immunogenicity and found to protect mice against lethal MHV infection (Talbot et al, 1988;Koolen et al, 1990).…”