Evidence for At Least Four Antigenic Sites on Type O Foot-and-Mouth Disease Virus Involved in Neutralization; Identification by Single and Multiple Site Monoclonal Antibody-resistant Mutants

Abstract

SUMMARYNeutralizing monoclonal antibodies raised against type 0 foot-and-mouth disease virus have been characterized on the basis of their reactivity with a panel of single site monoclonal antibody-resistant mutants which had defined three antigenic sites. Five antibodies neutralized all these mutants, but by selecting further single site mutants with one of these antibodies it was possible to define a fourth site involved in virus neutralization. Two monoclonal antibodies still neutralized these mutants and all multiple site resistant mutants. One multiple site resistant mutant was resistant to neutralization at each of four antigenic sites but was still efficiently neutralized by type 0 convalescent cattle sera. The relationship between sites recognized by different monoclonal antibodies generated in different laboratories is discussed. INTRODUCTIONStudies on the antigenic structure of two picornaviruses, poliovirus and rhinovirus, have been considerably enhanced by the solving of their three-dimensional crystal structure (Hogle et al., 1985;Rossmann et al., 1985) and the isolation and sequence analysis of monoclonal antibody (MAb) escape mutants (Minor et al., 1986;Sherry et al., 1986). Crystallographic studies on footand-mouth disease virus (FMDV), another picornavirus, are also in progress (Fox et al., 1987) and a number of laboratories have generated MAbs capable of neutralizing type O virus. characterized some 30 MAb-resistant mutants of the O1 Kaufbeuren strain of FMDV isolated using five different neutralizing MAbs. Three distinct antigenic sites were involved in virus neutralization. In this context the term antigenic site is used to describe an area of the virus surface which may contain several MAb epitopes; if one epitope is changed and this affects the ability of a second MAb to neutralize the virus then it is considered that the second MAb recognizes an epitope in the same antigenic site as that changed.Recently Stave et al. (1988) have used different MAbs to define three sites of neutralization. In this communication we now use the panel of mutants generated by Xie et al. (1987) to map the binding sites of MAbs generated in different laboratories and then use these antibodies to show the existence of further sites involved in the neutralization of type O FMDV. We have also generated multiple site mutants which are resistant to neutralization at each of two, three or four sites.

Insights into neutralization of animal viruses gained from study of influenza virus

“…Attachment of other viruses may be reduced by the binding of antibody but the magnitude of the reduction in attachment makes only a contribution to the neutralization found. A very clear illustration of the fact that IgG does not necessarily affect attachment is provided by those neutralization escape mutants which still bind their selecting monoclonal antibody [35,41].…”

Predicting antigenic sites on the foot-and-mouth disease virus capsid of the South African Territories types using virus neutralization data

“…The majority of these mAbs were against Euro-Asian serotypes A, O and C (Xie et al, 1987;Thomas et al, 1988;Baxt et al, 1989;Bolwell et al, 1989;McCahon et al, 1989;Kitson et al, 1990;Saiz et al, 1991;Crowther et al, 1993a). Only one report described the mapping of epitopes to a SAT2 virus (RHO/1/48) isolated in 1948 (Crowther et al, 1993b), with residues 147-149 and 156 in the flexible and surface-exposed G-H loop of 1D proven to be important in in vitro neutralization by a mAb.…”

“…The hydrophilicity and deduced surface exposure were also considered for each residue and highly variable regions correlated with regions of significant hydrophilicity (see Supplementary material). Comparison of the P1 amino acid sequences of SAT1 and 2 with type A and O sequences, revealed that many of the SAT1 and 2 hypervariable regions corresponded or were located in close proximity to previously identified immuno-dominant sites on types O and A (Table 4; Xie et al, 1987;Thomas et al, 1988;Baxt et al, 1989;Bolwell et al, 1989;McCahon et al, 1989;Kitson et al, 1990;Saiz et al, 1991;Crowther et al, 1993a). Some hypervariable regions were located within flexible structural loops or downstream of protease cleavage sites.…”

“…The outer capsid proteins are directly involved in antigenicity since 30-50 % of their residues are exposed on the virion surface, many of which constitute neutralizing epitopes (Acharya et al, 1989;Logan et al, 1993;Lea et al, 1995;Mateu, 1995;Usherwood & Nash 1995). Although several antigenic sites have been identified for A and O serotypes (Xie, et al, 1987;Thomas et al, 1988;Baxt et al, 1989;Bolwell et al, 1989;McCahon et al, 1989;Kitson et al, 1990;Saiz et al, 1991;Crowther et al, 1993a), a dearth of knowledge exists for the epitopes of the SAT types. Identification of those residues that comprise the antigenic determinants of the SAT viruses will allow the identification of those changes in outbreak strains that may cause escape from protection afforded by the vaccine.…”

Deconvolution of fully overlapped reflections from crystals of foot-and-mouth disease virus O1G67

“…The structures of two viruses closely related to G67 are known, namely virus OIBFS (Acharya et al, 1989), which differs from G67 by 11 mutations in the four capsid proteins, and virus O~K (manuscript in preparation) which differs at only six positions. G67 is, in fact, derived from virus O~K by growing O~K in vitro in the presence of the selective pressures imposed by antibodies recognising the virus (Kitson, McCahon & Belsham, 1990;McCahon et al, 1989).…”