Total and isotype humoral responses in cattle vaccinated with foot and mouth disease virus (FMDV) immunogen produced either in bovine tongue tissue or in BHK-21 cell suspension cultures.

The anti-foot and mouth disease virus (FMDV) serum antibody activity of protected and non protected animals immunized with inactivated FMDV originated in either bovine tongue tissue (BTTV vaccines) or BHK-21 cell suspension cultures (BHKV vaccines) was evaluated. The results show that 80-100% of the BTTV immunized and only 40-60% of the BHKV immunized animals with liquid-phase blocking sandwich ELISA (lp ELISA) serum titres of 1.5-1.7 U, were protected against the challenge with any of the four infectious FMDV argentine reference strains. This difference becomes almost marginal among BTTV and BHKV vaccinated animals with a strong anti-FMDV humoral response (i.e. lp ELISA titres > or = 1.95 U). Isotyping of the anti-FMDV response in immunized cattle with low lp ELISA titres revealed that BTTV vaccines were able to induce remarkably higher anti-FMDV IgG1 titres than their BHKV counterparts (i.e. mean titres of 1.95 and 1.35 U. respectively). This difference in specific IgG1 serum levels induced by BTTV and BHKV vaccines seems to be also limited to those animals with low anti-FMDV lp ELISA titres. These results together with the fact that the specific serum IgG1, but not the IgG2, isotype response of 219 vaccinated animals correlates almost linearly with their capacity to pass the challenge, suggests that the superior performance of BTTV vaccines is close related to their ability to raise a stronger anti-FMDV IgG1 response than BHKV vaccines.