Influence of vaccine potency and booster administration of foot-and-mouth disease vaccines on the antibody response in calves with maternal antibodies
BACKGROUND Maternal antibodies can interfere with foot-and-mouth disease vaccination. In this study we determined whether intratypic heterologous vaccination could help to improve herd immunity. RESULTS In unvaccinated calves, a half-life of maternal antibodies of 21 days was determined. At two weeks of age, calves without maternal antibodies showed a good antibody response against both vaccines used in the trial, while in calves with maternal antibodies no antibody response to homologous vaccination (A Turkey 14/98) but a limited antibody response to intratypic heterologous vaccination (A22 Iraq) was observed. CONCLUSION Two weeks old calves without maternal antibodies respond well to vaccination, but when emergency vaccination is carried out in a region that uses prophylactic vaccination, using an intratypic heterologous vaccine strain may improve the immunity in calves with maternal antibodies.