A NOVEL PROBIOTIC BASED ORAL DELIVERY VACCINE FOR BOVINE TUBERCULOSIS

Bovine tuberculosis (bTB), caused by Mycobacterium tuberculosis variant bovis (MBO), is one of the most damaging diseases in agriculture worldwide. The rise in BTB infected deer and cattle herds in Michigan, has led to a state of urgency due to associated animal trade and movement restrictions. Controlling the disease in animals is a primary approach to preventing/mitigating spread of MBO into and from wildlife or human populations. Attenuated Mycobacterium bovis BCG has long been used as a vaccine against TB and BTB, and a recent meta-analysis of ~1,300 studies reported a relatively low direct protection of BCG against infection, with a pooled efficacy estimate of 25%, and significant reduction in the frequency and severity of pathology of BTB in vaccinated animals but did not eliminate infection. Thus, we propose a novel subunit vaccine design around a central paradigm of microbial pathogenesis that posits that immune responses against virulence factors, such as ESAT-6, CFP-10, MarP, and Ag85b, are sufficient and effective to protect animals against MBO infection. These highly conserved immunogenic peptides/proteins from M. tuberculosis Complex will be genetically engineered into the ubiquitous soil bacterium, Bacillus subtilis, to be expressed and displayed on its spores. Recombinant spores are heat- stable, easily stored, and easily administered mucosal (oral or intranasal) vaccine. Recombinant spores will be tested, in this study, for their ability to elicit anti-MBO cellular and humoral immune responses and in-vivo tested for bacterial killing using a Matrigel system, after intranasal or oral immunization of calves.Aims: This proposal addresses a ­novel mucosal delivery vaccine concept through 1) testing our next generation oral subunit vaccines packaged in a probiotic bacterium to target mucosal immune responses against M. bovis in young animals, and 2) employing an in-vivo matrigel challenge system to evaluate protective immunity as the new target endpoint for defining vaccine efficacy.