Cross-Serotype Reactivity of ELISAs Used to Detect Antibodies to the Structural Proteins of Foot-and-Mouth Disease Virus

Abstract

Antibodies to the foot-and-mouth disease virus (FMDV) capsid induced by infection or vaccination can provide serotype-specific protection and be measured using virus neutralization tests and viral structural-protein (SP-)ELISAs. Separate tests are needed for each serotype, but cross-serotype reactions complicate serotyping. In this study, inter-serotypic responses were quantified for five SP-ELISA formats by testing 294 monovalent mainly bovine sera collected following infection, vaccination, or vaccination and infection with one of five serotypes of FMDV. Over half of the samples, representing all three immunization categories, scored positive for at least one heterologous serotype and some scored positive for all serotypes tested. A comparative approach to identifying the strongest reaction amongst serotypes O, A and Asia 1 improved the accuracy of serotyping to 73–100% depending on the serotype and test system, but this method will be undermined where animals have been infected and/or vaccinated with multiple FMDV serotypes. Preliminary studies with stabilized recombinant capsid antigens of serotypes O and A that do not expose internal epitopes showed reduced cross-reactivity, supporting the hypothesis that capsid integrity can affect the serotype-specificity of the SP-ELISAs. The residual cross-reactivity associated with capsid surface epitopes was consistent with the evidence of cross-serotype virus neutralization.

Production and characterization of monoclonal antibodies against foot-and-mouth disease virus serotype O and development of a sandwich ELISA for virus antigen detection

“…The increased OD values probably points to the contribution of serotype O internal antigens following heat treatment in addition to the exposed epitopes. Similar observation has been reported in a recent study by Ludi et al ( 2022 ). Since all the MAbs exhibited higher reactivity against heat treated type O antigen it is assumed that their epitopes are linear in nature.…”

Intradermal Inoculation of Inactivated Foot-and-Mouth Disease Vaccine Induced Effective Immune Responses Comparable to Conventional Intramuscular Injection in Pigs

“…The immunogenicity of a vaccine is mainly evaluated with a specific antibody against structural proteins constituting the FMDV capsid and a VN antibody. Antibodies for structural proteins are used as indicators of previous infection or the immunization of the specific FMDV serotype [ 22 ]. IgG, the major type of antibody, is induced from 4 to 7 DPV and reaches its maximum level at 21 DPV [ 23 ].…”

Expression of VP1 protein of foot-and-mouth disease virus serotype O originated from Indonesia in mammalian cells as potential immunogen

“…These experimental animals and natural hosts' immune responses led to the production of virus-neutralizing antibodies and viral challenge protection [1]. For diagnostic application, VP1 protein type O was expressed in E. coli, and the purified antibodies and protein were then tested against clinical samples from various serotypes using the ELISA method [19][20][21].…”