ROLE OF LIPOPOLYSACCHARIDE AND A MAJOR OUTER-MEMBRANE PROTEIN FROM FRANCISELLA-TULARENSIS IN THE INDUCTION OF IMMUNITY AGAINST TULAREMIA

A crude outer membrane preparation from Francisella tularensis Live Va ccine Strain (LVS) was toed to immunize mice. Immunized mice were comp letely protected from a F, tularensis challenge. We evaluated the role of two major outer membrane antigens in the induction of protective i mmunity, namely lipopolysaccharide and an outer membrane protein FopA, We presented FopA to the immune system using an aromatic amino acid-d ependent Salmonella typhimurium as a vector. Although mice mounted an immune response to cloned FopA no significant protection was induced. However, LPS immunized mice were completely protected We conclude that LPS is a major protective antigen whereas FopA has a limited or no ro le in the induction of protective immunity.