Intravenous BCG vaccination provides better protection for neonatal mice than for adult mice infected with Mycobacterium tuberculosis 9221

Description Here we compare the immune responses of intravenously (IV) BCG-vaccinated neonatal and adult mice infected with Mycobacterium tuberculosis (Mtb). We found that IV BCG vaccination significantly reduced lung and spleen bacterial burdens in Mtb-infected neonatal mice compared with Mtb-infected adult mice. The reduced bacterial burden in the spleens of IV BCG-vaccinated Mtb-infected neonatal mice was more noticeable than that in the lungs. IV BCG vaccination significantly increased IL-2, IL-3, IL-15 and IP-10 levels and reduced IL-1α and Gro-α production in the lungs of neonatal mice infected with Mtb. IV BCG vaccination significantly increased the number of CD8+ T cells and reduced the CD11b+Ly6G+ and CD4+ cell populations in the lungs of neonatal mice infected with Mtb compared with the lungs of Mtb-infected adult mice. In the spleen, neonatal BCG vaccination increased the number of CD11b+Ly6G+, CD11b+CD11c+, B220+, and CD3-NK1.1+CD27+ cells and decreased the number of CD11b+ and CD11c+MHCII+ cells in Mtb-infected mice. Our findings suggest that IV BCG vaccination can provide better protection against pulmonary and extrapulmonary tuberculosis in neonates compared to adults.