Monitoring of the immune response to B-abortus S19 conjunctival vaccine in cattle

Brucella abortus S19strain is one of the most preferred strains in vaccines against brucellosis in cattle. However, monitoring of the B. abortus S19 vaccine is difficult due to non availability of sustainable immunoreactive antigen and accurate test method. In this study, the humoral and the cellular immune responsesto S19 vaccine in one year old heifers and calves were monitored on post vaccination days (pvd) of 46, 85 and 169. Thus, the levels of Immunoglobulin (Ig) G and IgA isotypes against lipopolysaccharide (LPS) for humoral immunity and interferon gamma (IFNg) against brucellergen for cellular immune response were investigated by home-made ELISAs. In this study, significant IgG positivity was observed on pvd 46 in calves (100%) and heifers (96.6%), but IgA positivity and IFNg levels were not over 50%. Moreover, percentage of positive animals for IFNg (13.3-43.3%) and IgA (0-44%) have shown no significance for monitoring the vaccine throughout the study. Therefore, IgG levels can be used to monitor the efficiency of Brucella abortus S19 conjunctival vaccine in cattle. On the other hand, novel antigen combinations along with brucellergen and LPS for monitoring the immunity would enhance the sensitivity of the test and could be recommended for future investigations.