Fig 9. B. abortus RNA-mediated MHC-I inhibition correlates with diminished Ag presentation to MHC-I-restricted CD8⁺ T cells.

BMM from WT (A) and TLR7 KO (B) mice were treated with different doses of B. abortus RNA in the presence of mIFN-γ for 48 h. Then cells were washed and incubated with 20 ng/ml of 257–264 OVA peptide (SIINFEKL) for 20 min at 37°C. BMM from WT (A) and TLR7 KO (B) mice were washed and cultured for 0, 4, 6 and 18 h at 37°C with B3Z cells, a T cell hybridoma specific for OVA-K^b, which carries a β-galactosidase construct driven by NF-AT elements from the IL-2 promoter. T cell activation was measured using a colorimetric assay for LacZ activity with o-nitrophenyl-P-D-galactoside as a substrate. Background absorbance values obtained for BMM cultured in the absence of OVA were subtracted. ***P<0.001 vs. mIFN-γ-treated.