Anatomical distribution of Mycobacterium bovis genotypes in experimentally infected white-tailed deer.

Mycobacterium bovis (M. bovis) causes tuberculosis in white-tailed deer (WTD). Natural infection of WTD with M. bovis is most closely mimicked by instilling inoculum into palatine tonsillar crypts. One hundred fifty days after intratonsillar inoculation, M. bovis was cultured from 30 tissues originating from 14 deer. Whole-genome sequencing (WGS) was performed on the original inoculum, single colonies subcultured from the original inoculum, and M. bovis isolated from each culture positive tissue. Single nucleotide polymorphisms (SNP) were identified by comparing the derived sequences to the reference strain AF2122/97. Results indicate that the majority of the SNPs that were identified were homogeneous between the inoculum and the isolates from the tissues. The majority of individual tissues had different WGS genotypes from each other, suggesting that dissemination of M. bovis beyond the initial site of infection may require few mycobacteria representing a bottleneck.