Evidence, Challenges, and Knowledge Gaps Regarding Latent Tuberculosis in Animals

Area of Science:

• Veterinary Microbiology
• Infectious Diseases
• Pathogen Biology

Background:

• Mycobacterium bovis and other Mycobacterium tuberculosis complex (MTBC) pathogens causing animal tuberculosis receive less research focus than human TB-causing M. tuberculosis.
• Human TB involves heterogeneous mycobacterial subpopulations (actively replicating, non-replicating, dormant) linked to infection stages and latent TB (LTB).
• It remains unclear if similar bacterial phenotypic states drive LTB in animals.

Purpose of the Study:

• To review evidence, challenges, and knowledge gaps concerning LTB in animals.
• To explore host-pathogen differences between M. tuberculosis and M. bovis during infection.
• To consider models for investigating bacterial phenotypic states' influence on animal TB stages.

Main Methods:

• Literature review of existing studies on animal tuberculosis and latent infection.
• Comparative analysis of host-pathogen interactions in human versus animal MTBC infections.
• Exploration of potential host biomarkers and mycobacterial factors (DosR regulon, sigma factors, Rpf) relevant to LTB.

Main Results:

• Evidence for LTB in animals is less established than in humans, with significant knowledge gaps.
• Potential differences in host responses and MTBC strain virulence may influence LTB development in animals.
• Bacterial phenotypic states, similar to those in human TB, are hypothesized to play a role in animal LTB.

Conclusions:

• Further research is needed to understand LTB in animals, including host-pathogen dynamics and bacterial adaptation.
• Adapting human TB research models and identifying specific biomarkers are crucial for advancing animal LTB studies.
• Investigating mycobacterial factors like the DosR regulon and resuscitation-promoting factors may reveal mechanisms underlying LTB in animals.