Protective response to subunit vaccination against intranasal Burkholderia mallei and B. pseudomallei challenge

Abstract

<i>Burkholderia mallei</i> and <i>B. pseudomallei</i> are Gram-negative pathogenic bacteria, responsible for the diseases glanders and melioidosis, respectively. Furthermore, there is currently no vaccine available against these <i>Burkholderia</i> species. In this study, we aimed to identify protective proteins against these pathogens. Immunization with recombinant <i>B. mallei</i> Hcp1 (type VI secreted/structural protein), BimA (autotransporter protein), BopA (type III secreted protein), and <i>B. pseudomallei</i> LolC (ABC transporter protein) generated significant protection against lethal inhaled <i>B. mallei</i> ATCC23344 and <i>B. pseudomallei</i> 1026b challenge. Immunization with BopA elicited the greatest protective activity, resulting in 100% and 60% survival against <i>B. mallei</i> and <i>B. pseudomallei</i> challenge, respectively. Moreover, sera from recovered mice demonstrated reactivity with the recombinant proteins. Dendritic cells stimulated with each of the different recombinant proteins showed distinct cytokine patterns. In addition, T cells from immunized mice produced IFN-γ following <i>in vitro</i> re-stimulation. These results indicated therefore that it was possible to elicit cross-protective immunity against both <i>B. mallei</i> and <i>B. pseudomallei</i> by vaccinating animals with one or more novel recombinant proteins identified in <i>B. mallei</i>.