Reinfection as a central constraint on tuberculosis vaccine development

Area of Science:

• Immunology
• Vaccinology
• Infectious Diseases

Background:

• Tuberculosis (TB) vaccine development faces challenges due to lack of protection correlates and reinfection impact.
• Natural Mycobacterium tuberculosis infection offers limited protection against disease progression, especially in high-transmission settings.
• Existing TB vaccines show limited efficacy, highlighting the need for improved preclinical evaluation.

Purpose of the Study:

• To investigate the impact of repeated Mycobacterium tuberculosis infections on vaccine efficacy.
• To evaluate the utility of a multiple consecutive infection (MCI) model for preclinical TB vaccine assessment.
• To identify reinfection as a biological constraint on prophylactic TB vaccines.

Main Methods:

• Utilized an in silico multiple consecutive infection (MCI) model to simulate successive TB infections.
• Experimentally validated MCI predictions in the C3HeB/FeJ murine model.
• Assessed bacillary load, lesion pathology, and BCG efficacy under single and repeated infection conditions.

Main Results:

• MCI simulations predicted increased pulmonary bacillary load and decreased BCG efficacy with successive infections.
• Experimental infections confirmed increased bacillary burden but paradoxically altered inflammatory pathology.
• BCG provided only marginal additional protection under MCI conditions compared to single infection.

Conclusions:

• Reinfection is a critical biological constraint that diminishes the effectiveness of prophylactic TB vaccines.
• Preclinical evaluation strategies, including MCI models, must be reassessed to enhance predictive value.
• Prioritizing the prevention of disease in the context of reinfection is crucial for advancing TB vaccine development.