Multiple consecutive infections might explain the lack of protection by BCG

• Published in: PloS one Vol. 9; no. 4; p. e94736
• Main Authors: Cardona, Pere-Joan, Vilaplana, Cristina
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01.04.2014; Public Library of Science (PLoS)
• Subjects: Algorithms; Animal models; Animals; Bacillus Calmette-Guerin vaccine; BCG; BCG Vaccine - administration & dosage; BCG Vaccine - immunology; BCG vaccines; Biology and Life Sciences; Control; Data processing; Growth models; Health aspects; Humans; Immune response; Immune system; Infections; Lungs; Lymphatic system; Lymphocytes; Mathematical analysis; Mathematical models; Medicine and Health Sciences; Mice; Models, Immunological; Mycobacterium tuberculosis; Mycobacterium tuberculosis - immunology; Reproducibility of Results; Time Factors; Tuberculin Test; Tuberculosis; Tuberculosis - diagnosis; Tuberculosis - immunology; Tuberculosis - prevention & control; Tuberculosis vaccines; Vaccination - standards; Vaccines; Spain
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0094736

Although contacts between tuberculosis patients may result in multiple consecutive infections (MCI), no experimental animal models consider this fact when used in basic studies. Moreover, the current TB vaccine (BCG) has demonstrated a limited protection in humans. In this study we evaluate the effect of tuberculosis MCI by way of a simple mathematical analysis using data from the low dose aerosol murine experimental model. The results show that a higher number of, or shorter intervals between, multiple consecutive infections reduce the protective effect of BCG. This is due to both the increase in bacillary load at the stationary level of the infection, and the protective immune response induced by the infection itself. This factor must therefore be taken into account when designing new prophylactic strategies as candidate vaccines for the replacement of BCG.