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 o f protected and non protected animals immunized with inactivated FMDV originated in either bovine tongue tissue (BTTV vaccines) or BHK-21 ce ll suspension cultures (BHKV vaccines) was evaluated The results show that 80-100% of the BTTV immunized and only 40-60% of the BHKV immuniz ed animals with liquid-phase blocking sandwich ELISA (Ip 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 greater than o r equal to 1.95 U). Isotyping of the anti-FMDV response in immunized c attle with low lp ELISA titres revealed that BTTV vaccines were able t o induce remarkably higher anti-FMDV IgG1 titres than their BHKV count erparts (i.e. mean titres of 1.95 and 1.35 U, respectively). This diff erence in specific IgG1 serum levels induced by BTTV and BHKV vaccines seems to be also limited to those animals with low anti-FMDV Ip ELISA titres. These results together with the fact that the specific serum IgG1, bur not the IgG2, isotype response of 219 vaccinated animals cor relates almost linearly with their capacity to pass the challenge, sug gests that the superior performance of BTTV vaccines is close related to their ability to raise a stronger anti-FMDV IgG1 response than BHKV vaccines. (C) 1997 Elsevier Science Ltd.