Modelling of cerebral tuberculosis in BALB/c mice using clinical strain from patients with CNS tuberculosis infection.

BACKGROUND & OBJECTIVES: Central nervous system (CNS) infection caused by Mycobacterium tuberculosis (MTB) is the most severe form of extrapulmonary tuberculosis (EPTB) due to a high level of mortality and morbidity. Limited studies are available on CNS-TB animal model development. The present study describes the development of a murine model of CNS-TB using a clinical strain (C3) isolated from the cerebrospinal fluid (CSF) of CNS-TB patients. METHODS: Groups of mice were infected by the intravenous route with MTB C3 strain isolated from the CSF of CNS-TB patients. Brain and lung tissue were evaluated for bacterial burden, histopathology and surrogate markers of TB infection at 30 and 50 days post-infection. RESULTS: Mice infected intravenously with MTB C3 strains showed progressive development of CNS disease with high bacillary burden in lungs at the initial stage (30 days), which eventually disseminated to the brain at a later stage (50 days). Similarly, high mortality (60%) was associated in mice infected with C3 strain compared to control. INTERPRETATION & CONCLUSIONS: The study showed development of a novel murine model of CNS-TB using the C3 strain of MTB that replicated events of extrapulmonary dissemination. The developed model would be helpful in understanding the pathogenesis of CNS-TB infection for the development of improved therapeutic interventions in future.

Assessment of immunological markers and booster effects of Ag85B peptides, Ag85B, and BCG in blood of BCG vaccinated children: a preliminary report.

PURPOSE: In the present study, the protective immunological markers in serum and peripheral blood mononuclear cells (PBMCs) of bacillus Calmette-Guérin (BCG) vaccinated and unvaccinated children were evaluated after vaccination. Further, PBMCs of children with low protective levels were boosted with BCG, Ag85B, and Ag85B peptides to study their booster effects to increase waning BCG induced immunity. MATERIALS AND METHODS: Fifty children from 1 month to 18 years of age were randomized for the study. Blood samples were collected from 27 participants with/without BCG vaccination. Immunological markers (anti-BCG, interferon γ [IFN-γ], and adenosine deaminase activity) were assessed in both serum and PBMCs of children. Children with low levels of protective immunological markers were further recruited and their PBMCs were boosted with BCG, Ag85B, and Ag85B peptides. RESULTS: Children in age group of 4-6 years were associated with significantly (p<0.05) higher BCG-specific IgG and IFN-γ levels compared to those in age group greater than 10 years. Vaccinated children had greater repertoire of immunological memory which on in vitro stimulation with BCG showed increase in BCG-specific response compared to unvaccinated controls. Assessment of booster effects of BCG, Ag85B, and Ag85B peptides in PBMCs of children revealed greater potential of peptides to boost BCG induced immunity compared to BCG and Ag85B. CONCLUSION: To conclude, children within age 4-6 years are associated with high immunological markers which eventually diminish with age thereby suggesting need for booster dose in later years. Mycobacterium tuberculosis peptides along with BCG may be used as attractive candidates to boost such waning BCG induced immunity in children.