Whole Genome Sequencing for Determining the Source of Mycobacterium bovis Infections in Livestock Herds and Wildlife in New Zealand.

The ability to DNA fingerprint Mycobacterium bovis isolates helped to define the role of wildlife in the persistence of bovine tuberculosis in New Zealand. DNA fingerprinting results currently help to guide wildlife control measures and also aid in tracing the source of infections that result from movement of livestock. During the last 5 years we have developed the ability to distinguish New Zealand (NZ) M. bovis isolates by comparing the sequences of whole genome sequenced (WGS) M. bovis samples. WGS provides much higher resolution than our other established typing methods and greatly improves the definition of the regional localization of NZ M. bovis types. Three outbreak investigations are described and results demonstrate how WGS analysis has led to the confirmation of epidemiological sourcing of infection, to better definition of new sources of infection by ruling out other possible sources, and has revealed probable wildlife infection in an area considered to be free of infected wildlife. The routine use of WGS analyses for sourcing new M. bovis infections will be an important component of the strategy employed to eradicate bovine TB from NZ livestock and wildlife

Oral Delivery of Mycobacterium bovis BCG in a Lipid Formulation Induces Resistance to Pulmonary Tuberculosis in Mice

A lipid-based formulation has been developed for oral delivery of Mycobacterium bovis bacille Calmette-Guérin (BCG) vaccine. The formulated M. bovis BCG was fed to BALB/c mice to test for immune responses and protection against M. bovis infection. The immune responses included antigen-specific cytokine responses, spleen cell proliferation, and lymphocyte-mediated macrophage inhibition of M. bovis. Oral delivery of formulated M. bovis BCG to mice induced strong splenic gamma interferon levels and macrophage inhibition of virulent M. bovis compared with results with nonformulated M. bovis BCG. Formulated oral M. bovis BCG significantly reduced the bacterial burden in the spleen and lungs of mice following aerosol challenge with virulent M. bovis. Our data suggest that oral delivery of formulated M. bovis BCG is an effective means of inducing protective immune responses against tuberculosis. Lipid-based, orally delivered mycobacterial vaccines may be a safe and practical method of controlling tuberculosis in humans and animals

Assessment of Live Candidate Vaccines for Paratuberculosis in Animal Models and Macrophages▿

Mycobacterium avium subsp. paratuberculosis (basonym M. paratuberculosis) is the causative agent of paratuberculosis, a chronic enteritis of ruminants. To control the considerable economic effect that paratuberculosis has on the livestock industry, a vaccine that induces protection with minimal side effects is required. We employed transposon mutagenesis and allelic exchange to develop three potential vaccine candidates, which were then tested for virulence with macrophages, mice, and goats. All three models identified the WAg906 mutant as being the most attenuated, but some differences in the levels of attenuation were evident among the models when testing the other strains. In a preliminary mouse vaccine experiment, limited protection was induced by WAg915, as evidenced by a reduced bacterial load in spleens and livers 12 weeks following intraperitoneal challenge with M. paratuberculosis K10. While we found macrophages and murine models to be rapid and cost-effective alternatives for the initial screening of M. paratuberculosis mutants for attenuation, it appears necessary to do the definitive assessment of attenuation with a ruminant model