Protection of mice against brucellosis by vaccination with Brucella melitensis WR201(16M Delta purEK)

Human brucellosis can be acquired from infected animal tissues by ingestion , inhalation, or contamination of the conjunctiva or traumatized skin by in fected animal products. A vaccine to protect humans from occupational expos ure or from zoonotic infection in areas where the disease is endemic would reduce an important cause of morbidity worldwide. Vaccines currently used i n animals are unsuitable for human use. We tested a live, attenuated, purin e-auxotrophic mutant strain of Brucella melitensis, WR201, for its ability to elicit cellular and humoral immune responses and to protect mice against intranasal challenge with B. melitensis 16M. Mice inoculated intraperitone ally with WR201 made serum antibody to lipopolysaccharide and non-O-polysac charide antigens. Splenocytes from immunized animals released interleukin-2 (IL-2), gamma interferon, and IL-10 when cultured with Brucella antigens. Immunization led to protection from disseminated infection but had only a s light effect on clearance of the challenge inoculum from the lungs. These s tudies suggest that WR201 should be further investigated as a vaccine to pr event human brucellosis.