ISOTYPE-SPECIFIC ANTIBODY-RESPONSES TO FOOT-AND-MOUTH-DISEASE VIRUS IN SERA AND SECRETIONS OF CARRIER AND NON-CARRIER CATTLE

Isotype-specific antibody responses to foot-and-mouth disease virus (F MDV) were measured in the sera and upper respiratory tract secretions of vaccinated and susceptible cattle challenged with FMDV by direct co ntact or by intranasal inoculation. A comparison was made between catt le that eliminated FMDV and those that developed and maintained a pers istent infection. Serological and mucosal antibody responses were dete cted in all animals after challenge. IEA and IgM were detected before the development of IgG(1) and IgG(2) responses. IgM was not detected i n vaccinated cattle. Challenge with FMDV elicited a prolonged biphasic secretory antibody response in FMDV 'carrier' animals only. The respo nse was detected as FMDV-specific IgA in both mucosal secretions and s erum samples, which gained statistical significance (P < 0.05) by 5 we eks after challenge. This observation could represent the basis of a t est to differentiate vaccinated and/or recovered convalescent cattle f rom FMDV 'carriers'.