Pamela Ncube Poster 2025

 Miss Pamela Ncube

Stellenbosch University, South Africa

Genotypic and phenotypic assessment of Mycobacterium bovis persisters from wildlife specimens following in vitro stress

Poster Abstract

Mycobacterium tuberculosis (M. tb) infection in humans can either progress to tuberculosis (TB) disease, or in many patients, be contained and lead to a latent infection without evidence of active disease. It is, however, unknown whether a similar scenario exists in animals infected with M. bovis. Since management strategies may differ for latently infected animals, it is important to evaluate whether M. bovis can form persisters, believed to underlie latent infection in humans. M. tb infection in humans. If latent M. bovis infection occurs in animals, it would impact our understanding of risks for intra- and inter-species transmission and host protective responses, especially to TB vaccines.

In this this study, we aimed to characterize M. bovis persister formation upon in vitro acid stress which mimics the macrophage phagolysosome microenvironment. Tissue specimens (23) from naturally infected M. bovis wildlife species including wild dogs, warthogs, lions and buffalos were collected in South Africa. The specimens were decontaminated, purified and then genotyped using spoligotyping and whole genome sequencing. A replication reporter assay was used to identify viable but non- or slowly-replicating bacterial (VBNR) populations, which underlie the persister phenotype.

Our preliminary results from in vitro acid stress experiments demonstrated that, M. bovis strains (with different genotypes) differ in VBNR populations in response to in vitro acid stress. We, therefore, support the hypothesis that some M. bovis strains are capable of forming persisters. Capability of M. bovis to persist as VBNR bacilli has important implications for understanding TB pathogenesis TB. Differentiating stages of infection is essential to inform TB vaccine design for animals and humans. In addition, understanding comparative host responses are crucial for improving diagnostic tools, and evaluating protection as well as screening programmes that support vaccine implementation and test whether vaccines for M. tuberculosis could also protect against M. bovis infection.