Evaluation of Campylobacter fetus subspecies concentrations in commercial bovine reproductive vaccines.

Abstract

Campylobacter fetus is an important etiological agent of reproductive infections in cattle, which can be managed through vaccination. Nevertheless, the efficacy of bovine reproductive vaccines against C. fetus remains uncertain due to the absence of standardized guidelines and variable vaccine formulations. Thus, this study aimed to quantify and compare C. fetus subsp. fetus (Cff) and C. fetus subsp. venerealis (Cfv) in six commercial reproductive vaccines current available in Brazil in 2022. We observed significant differences in the estimated number of genome copies of Cff and Cfv among the tested vaccines. Analysis of vaccine cost and antigen concentration revealed no direct correlation between price and C. fetus antigen concentration. These findings underscore the discrepancies in antigen titration among bovine reproductive vaccines and highlight the lack of informative labeling in current commercial products. Altogether, there is a pressing need for standardized guidelines for C. fetus vaccinal doses to ensure consistent bacterial loads and efficient immunization of the herds. Nevertheless, more studies regarding vaccine efficiency are required to ensure an appropriate immune response in cattle herds.