Protective Effect of β‐Glucan Against Mycobacterium bovis, BCG Infection in BALB/c Mice

Open Access
Publisher Website
Google Scholar
Abstract
β-1,3-Glucan is a potent stimulator of macrophage functions and has a protective effect against a range of infections in rodent models. We examined whether the agent could also protect against the intracellular Mycobacterium bovis, bacillus Calmette–Guérin (BCG) infection in mice. BCG-susceptible BALB/c mice were injected intravenously (i.v.) with β-glucan or vehicle 3 days before, or with β-glucan 7 days after i.v. challenge with live BCG bacilli. The animals were killed 4 or 8 weeks later, their organs were homogenized and applied to object slides and stained with auramin for counting of bacilli, or seeded onto agar in Petri dishes. Mice treated with β-glucan both pre- and postchallenge had significantly lower numbers of BCG bacilli and BCG colony-forming units in spleen homogenates compared with controls 4 weeks after challenge. A similar, but not statistically significant, tendency was observed in spleen homogenates from mice killed 8 weeks after challenge. In homogenates of liver and lungs there were similar findings, but less pronounced. There was a dose-dependent effect of β-glucan injected before BCG challenge on the number of BCG bacilli found in spleen and liver homogenates. In addition, antibody cross-reactivity was demonstrated between M. tuberculosis cell wall and β-glucan. The results suggest that β-glucan has a protective effect against M. bovis, BCG infection in susceptible mice.