IDENTIFICATION OF NATIVE FOOT-AND-MOUTH-DISEASE VIRUS NONSTRUCTURAL PROTEIN 2C AS A SEROLOGICAL INDICATOR TO DIFFERENTIATE INFECTED FROM VACCINATED LIVESTOCK

Cattle and pigs which have been vaccinated against foot-and-mouth dise ase can be distinguished from convalescent animals by radio-immunoprec ipitation and sodium dodecyl sulphate polyacrylamide gel electrophores is of the virus-induced proteins reacting with the respective sera. Ba by hamster kidney cells infected with foot-and-mouth disease virus (FM DV) (serotype A(24)) were labelled with S-35-methionine and the virus- induced proteins were precipitated with sera from vaccinated and subse quently challenged animals, convalescent animals retained for over 300 days, animals vaccinated or infected with viruses belonging to all se rotypes of FMDV, and animals infected with encephalomyocarditis (EMC) or porcine or bovine enteroviruses. In addition to the structural prot eins of the virus, the non-structural proteins 2C, 3ABC, 3C, 3CD and 3 D were precipitated by convalescent sera, but only 3D was precipitated by serum from vaccinated animals. Proteins L, 2C and 3C were precipit ated only after challenge with a heterotypic virus (serotype 0(1) Tuni sia), indicating that virus replication of the challenge virus had tak en place. No precipitation was detected with sera from EMC or enterovi rus-infected animals. The results indicate that protein 2C, and to a l esser extent the polypeptide 3ABC, could be used to differentiate pote ntial carrier convalescent animals from vaccinated livestock.