Co-immunization of cattle with a vaccine against babesiosis and Lactobacillus casei increases specific IgG1 levels to Babesia bovis and B. bigemina.

The effect of Lactobacillus casei administered along with a live attenuated vaccine vs. bovine babesiosis (VAC) on induction of IgG1 and IgG2 antibodies to Babesia bovis and Babesia bigemina was assessed by the indirect fluorescent antibody test (IFAT) in bovines of an endemic babesiosis area before (day 0) and after vaccination (days 15 and 30). We previously reported that L. casei increases the efficiency of VAC under controlled conditions and under extreme conditions in the field; however, the levels of IgG1 and IgG2 antibodies to B. bovis and B. bigemina are not known in vaccinated animals. Twenty-one dairy cows were allocated into three groups (seven animals per group): unvaccinated, vaccinated with VAC and vaccinated simultaneously with VAC and L. casei (VAC-LC). All animals were kept in a babesiosis endemic area at Tlalixcoyan, Veracruz. At days 15 and 30 after vaccination, the average levels of IgG1 to B. bovis and to B. bigemina were significantly higher in VAC-LC group than levels observed in VAC and control groups (P<0.01). Levels of IgG2 were similar in VAC and VAC-LC groups but higher than in the control group (P<0.01). When tested in in vitro cultures of B. bovis, sera from VAC-LC group significantly inhibited parasite growth as compared with the sera of the other two groups. It is suggested that the efficiency improvement of VAC, in part, is due to the L. casei boost of IgG1 over IgG2 antibodies to B. bovis and B. bigemina when the bacteria is co-inoculated with this vaccine.