Immune response of calves immunized with cocktail of DNA vaccine encoding complexed outer membrane proteins from anaplasma marginale

Abstract

In the present study we evaluated a cocktail of recombinant plasmids encoding the major surface proteins (rMSP1a, rMSP1b, rMSP4, rMSP5, VirB9 and VirB10) to improve the humoral and celular immune response triggered in calves. Ten calves were divided in three groups: Four calves were inoculated with the plasmids/rMSPs (G1); 2 calves were inoculated with empty vector (G2); and 4 calves received saline (G3). Three inoculations were administered at 21-day intervals. In G1, the calves showed significant increases in total IgG level 21 days after the second inoculation, compared to the control group (p<0,05%), and G1 calves remained above the cut-off value 28 days after the third inoculation (p<0,05%). The post-immunized sera from calves in G1 reacted specifically for each of the rMSPs used. Additionally, ELISA detected specific IgG for VirB9 and VirB10. In conclusion, the cocktail of recombinant plasmids induced antigen-specific seroconversion in calves. Therefore, additional testing to explore the protection induced by recombinant plasmids, alone or in conjunction with proteins previously identified as subdominant epitopes, is warranted.