[Heparin-binding hemagglutinin as a composition antigen of tuberculosis vaccine exerts protective immune effects by...

To explore the protective immune effect induced by mucosal delivery heparin-binding hemagglutinin (HBHA)-a candidate vaccine antigen of Mycobacterium tuberculosis. Female C57BL/6 mice were between 6 and 8 weeks of age before experimental use. Thirty mice received different immunization strategies and were randomly divided into the control group, the early secreting antigen target-6 (ESAT-6) intranasal immunization group, the HBHA intranasal immunization group, the BCG priming PBS control group, or BCG priming HBHA boost group, 6 mice in each group. In order to analyzed the immune effect, the concentrations of plasma Interleukin-17A (IL-17A) and other cytokines were measured by ELISA. Quantitative real-time PCR analyses were performed to detect the relative quantity (RQ) mRNA of IL-17A in the lung. The lung tissue sections were stained to detect the formation of the tertiary lymphoid structures. The chemokines contributed to formation of the tertiary lymphoid structures were also measured. Flow cytometry was used to detect the frequency of Th1 and Th17 cells in the system. Sixty mice in the BCG priming PBS control group and the BCG priming HBHA boost group were sacrificed at different time points after infection to count the lung bacterial burden. The concentrations of plasma IL-17A and relative quantity of lung IL-17A mRNA were highest in the BCG priming HBHA boost group [(14.76±4.73) pg/mL,RQ (12.27±6.71)], which was significantly higher than the control group [(5.57±2.95) pg/mL,RQ (1.30±0.97)] (t=4.213, P<0.001; t=5.984, P<0.001), and also significantly higher than the BCG priming PBS control group [(6.81±2.18) pg/mL,RQ (1.44±1.16)] (t=3.646 P=0.001; t=6.185 P<0.001). Compared with the BCG priming PBS control group (0.38±0.38)% the frequency of spleen Th17 cells were also significantly increased (t=-0.280, P=0.048) in the BCG-primary HBHA boost group (1.02±0.34)%. In addition, HBHA boosting could promote better formation of the tertiary lymphoid structures in the lung, and decrease the bacterial load on the early stage after BCG challenge. Collectively, mucosal delivery of HBHA can effectively enhance the protective effect after BCG vaccination, and it is a potential candidate vaccine component.