Major histocompatibility complex (DRB3) geneexpression pattern indicates differences in BrucellaabortusS19 vaccine induced immune responsein Karan Fries and Sahiwal cattle

Abstract

Brucella abortus S19 strain vaccination is most effectively used as a tool to control the brucellosis in cattle. To understand the genetic basis of differences in immune responsiveness after immunization in cattle of different genotypes, we assessedthe expression of MHC-DRB3 antigen receptor molecule in six each female calves of Karan Fries crossbreds (KF, Bos indicus x Bos taurus) and Sahiwal (Bos indicus) vaccinated with Brucella S19. Serum and peripheral blood mononuclear cells (PBMC) were isolated from blood collected on 0(before vaccination) and 7, 14 and 28 day of vaccination. Antigenic response was assessed for these days in both the groups using Rose Bengal Plate form Test (RBPT). At 0d, the calves of both groups showed no antigen agglutination, confirming the calves free from the infection.The serum of 7d onward started showing the agglutination with more strong response in later stages specifically in KF, indicating increased immune response against Brucella. Therefore, RBPT can be used as earliest screening (7d onward) for Brucella antigenic reactivity in both cattle groups. The expression of DRB3 gene started with slight upregulation after vaccination,in general, however without any significant differences between two different genetic groups upto14d.The significant (p Lass Than 0.01) higher expression (8 times) of DRB3was observed in KF than Sahiwal at 28d. The study indicated that antigenic reactivity and MHC-DRB3 expression elicited by Brucella S19 vaccination was more prominent in KFduring initial days, which may provide an extra advantage to the host for antigen binding, thereby better immune protection at later stage.