Melioidosis, the infectious disease caused by Burkholderia pseudomallei, is a world-wide problem of increasing importance. Endemic disease is more widespread than previously thought, with an epicenter in Southeast Asia and northern Australia, but also with a higher than previously realized incidence in South and Central America. While melioidosis is less of an acute health issue in the United States, recent publications suggest that the tropical (mainly Southern) states may be hospitable to B. pseudomallei, and thus represent a potential foothold for the disease in this country if released accidentally or intentionally. Due to its ability to cause disease when inhaled, B. pseudomallei has been designated by CDC as Tier I potential select agent. At present, there is no effective vaccine against this organism.
CompoVax melioidosis vaccine composition
Variations of the platform DNA vaccine that target B. pseudomallei infected cells include linked sequences encoding a full-length protein Hpc1, an immunogenic part of mutated (inactivated) N-terminal domain of TssM and a proprietary protein allowing intracellular transfer of the fusion antigen. TssM is a deubiquitinase that suppresses host immune response to B. pseudomallei infection, and Hcp1 is required for both the assembly of the type 6 secretion system and the export of its effectors. Antibodies against both TssM and Hcp1 have been found in high titers in the sera of culture-positive patients with melioidosis. After vaccination target cells start to produce and secrete a triple fusion composite antigen. This antigen can be presented on the surface of cells expressing it as well as on the surface of neighboring cells that are secondarily targeted by the produced vaccine.
