Transposon mutagenesis uncovers Brucella genes critical for evasion of host humoral immunity 2184

Abstract Description Brucellosis, caused by Brucella, is a significant global health threat to both animals and humans. Although vaccines like S19, RB51, and Rev1 are available for animals, they do not confer sterile immunity. Our previous studies demonstrated a protective role of antibodies in vaccine-mediated immunity against Brucella, however in primary infection antibodies were dispensable for control of Brucella. In this study, we utilized Tn-Seq to investigate how Brucella evades antibody-mediated immunity in vivo, during primary infection. We generated a library containing ∼2,400 B. melitensis mutants by introducing the Tn5 transposon into B. melitensis. Wild-type (WT) and antibody-deficient (sIgM-/-AID-/-) mice were then infected with this Tn mutant pool. Comparing the relative recovery of Tn mutants from the spleens of WT and sIgM-/-AID-/- mice, we identified 54 mutants that showed reduced survival in WT compared to sIgM-/-AID-/- mice. Additionally, we discovered 14 Tn insertions that were underrepresented by more than 10-fold in the output pool of WT mice relative to both the inoculum and the pool recovered from sIgM-/-AID-/- mice. These findings suggest that Brucella possesses genes specifically required for evading humoral immunity and understanding how Brucella circumvents antibody-mediated immunity could provide valuable insights for developing more effective brucellosis vaccines. Funding Sources NIH R21AI185488 Topic Categories Microbial, Parasitic, and Fungal Immunology (MPF)