<p class="MDPI12titleori">Antibodies to <em>Burkholderia pseudomallei </em>Outer Membrane Proteins Coupled to Nanovaccines Exhibit Cross-Reactivity to <em>B. cepacia </em>Complex and <em>Pseudomonas aeruginosa</em> Homologues

Burkholderia pseudomallei complex and B. cepacia complex are two evolutionary distinct clades of pathogens causing human disease. Most vaccine efforts have focused on the former group largely due to their biothreat status and global disease burden. It has been proposed that a vaccine could be developed that simultaneously protects against both groups of Burkholderia by specifically targeting conserved antigens. Only a few studies have set out to identify which antigens may be optimal targets for such a vaccine. We have previously assessed the ability of three highly conserved B. pseudomallei antigens, OmpA1, OmpA2, and Pal coupled to gold nanoparticles (nanovaccines), to protect mice against a homotypic B. pseudomallei challenge. Here, we have expanded our study by demonstrating that antibodies to each of these proteins show varying levels of reactivity to homologs in B. cepacia complex, with OmpA2 antibodies exhibiting the highest cross-reactivity. Remarkably, some immunized mice with our nanovaccines, particularly those that received OmpA2, produce antibodies that bind Pseudomonas aeruginosa, which harbor distantly related homologous proteins. T cells elicited to Pal and OmpA2 responded to stimulation with B. cepacia complex-derived proteins. Our study supports incorporation of these antigens, particularly OmpA2, for the development of a pan-Burkholderia vaccine.