Humoral immune response to 5 FMD vaccines (3 imported and 2 locally manufactured) available in Pakistan was studied in 90 buffalo calves over seven months period. All vaccines were trivalent and contained serotypes A, O and Asia-1. Sera were analyzed for the presence of antibodies against non-structural proteins (NSP) and structural proteins (SP) using commercially available 3ABC-trapping indirect ELISA and liquid phase blocking ELISA, respectively. Maternal NSP antibodies waned by 5^th month of age in most of the buffalo calves. Vaccine induced NSP antibodies were seen in only two animals, both vaccinated with locally manufactured unpurified vaccines. All three imported vaccines induced significantly higher titers against SP than local vaccines. These titers seemed to stay at protective level for almost six months in two imported vaccines which had aluminum hydroxide and saponin as adjuvant. Peak titers of both local vaccines were highest on day 30 post booster dose but these titers declined sharply and by day 60 post booster dose, the titers were much lower than the protective level. Oil adjuvanted FMD vaccines (both local and imported) did not induce sustained higher immune response in buffalo calves that are normally seen in cattle with these vaccines.

Key words: Buffalo calves, ELISA, Foot and mouth disease vaccines, Humoral immune response