Abstract
Anaplasma phagocytophilum Major surface protein 4 (MSP4) plays a role during infection and multiplication in host neutrophils and tick vector cells. Recently, vaccination trials with the A. phagocytophilum antigen MSP4 in sheep showed only partial protection against pathogen infection. However, in rabbits immunized with MSP4, this recombinant antigen was protective. Differences between rabbit and sheep antibody responses are probably associated with the recognition of non-protective epitopes by IgG of immunized lambs. To address this question, we applied quantum vaccinomics to identify and characterize MSP4 protective epitopes by a microarray epitope mapping using sera from vaccinated rabbits and sheep. The identified candidate protective epitopes or immunological quantum were used for the design and production of a chimeric protective antigen. Inhibition assays of A. phagocytophilum infection in human HL60 and Ixodes scapularis tick ISE6 cells evidenced protection by IgG from sheep and rabbits immunized with the chimeric antigen. These results supported that the design of new chimeric candidate protective antigens using quantum vaccinomics to improve the protective capacity of antigens in multiple hosts.