The autotransporter protein BatA is a protective antigen against lethal aerosol infection with and .

BACKGROUND

and are the causative agents of glanders and melioidosis, respectively. There is no vaccine to protect against these highly-pathogenic and intrinsically antibiotic-resistant bacteria, and there is concern regarding their use as biological warfare agents. For these reasons, and are classified as Tier 1 organisms by the U.S. Federal Select Agent Program and the availability of effective countermeasures represents a critical unmet need.

METHODS

Vaccines (subunit and vectored) containing the surface-exposed passenger domain of the conserved autotransporter protein BatA were administered to BALB/c mice and the vaccinated animals were challenged with lethal doses of wild-type and strains via the aerosol route. Mice were monitored for signs of illness for a period of up to 40 days post-challenge and tissues from surviving animals were analyzed for bacterial burden at study end-points.

RESULTS

A single dose of recombinant Parainfluenza Virus 5 (PIV5) expressing BatA provided 74% and 60% survival in mice infected with and , respectively. Vaccination with PIV5-BatA also resulted in complete bacterial clearance from the lungs and spleen of 78% and 44% of animals surviving lethal challenge with , respectively. In contrast, all control animals vaccinated with a PIV5 construct expressing an irrelevant antigen and infected with were colonized in those tissues.

CONCLUSION

Our study indicates that the autotransporter BatA is a valuable target for developing countermeasures against and and demonstrates the utility of the PIV5 viral vaccine delivery platform to elicit cross-protective immunity against the organisms.