| Summary: | <p>Abstract</p> <p>Background</p> <p>The bacterial biothreat agents <it>Burkholderia mallei </it>and <it>Burkholderia pseudomallei </it>are the cause of glanders and melioidosis, respectively. Genomic and epidemiological studies have shown that <it>B. mallei </it>is a recently emerged, host restricted clone of <it>B. pseudomallei</it>.</p> <p>Results</p> <p>Using bacteriophage-mediated immunoscreening we identified genes expressed <it>in vivo </it>during experimental equine glanders infection. A family of immunodominant antigens were identified that share protein domain architectures with hemagglutinins and invasins. These have been designated <it>Burkholderia </it>Hep_Hag autotransporter (BuHA) proteins. A total of 110/207 positive clones (53%) of a <it>B. mallei </it>expression library screened with sera from two infected horses belonged to this family. This contrasted with 6/189 positive clones (3%) of a <it>B. pseudomallei </it>expression library screened with serum from 21 patients with culture-proven melioidosis.</p> <p>Conclusion</p> <p>Members of the BuHA proteins are found in other Gram-negative bacteria and have been shown to have important roles related to virulence. Compared with other bacterial species, the genomes of both <it>B. mallei and B. pseudomallei </it>contain a relative abundance of this family of proteins. The domain structures of these proteins suggest that they function as multimeric surface proteins that modulate interactions of the cell with the host and environment. Their effect on the cellular immune response to <it>B. mallei </it>and their potential as diagnostics for glanders requires further study.</p>
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