Assessment of the Adjuvant Effects of Lentinan on the Tuberculosis Subunit Vaccine BG

<b>Objectives</b>: This study aims to assess the adjuvant effects of lentinan and its combination with Mn(J), a manganese-based colloidal adjuvant, on the BG (fusion protein BfrB-GrpE of <i>Mycobacterium tuberculosis</i>) subunit vaccine. <b>Methods</b>: A rabbit skin infection model was established to evaluate the immune protection conferred by the BG-lentinan vaccine, the BG-lentinan/Mn(J) vaccine, and the Bacillus Calmette-Guérin (BCG) vaccine against tuberculosis. Rabbits were vaccinated at weeks 0, 2, and 4. Six weeks post-vaccination, antigen-specific IgG levels were measured, followed by a BCG skin challenge. <b>Results</b>: Both the BG-lentinan and BG-lentinan/Mn(J) vaccines significantly increased antigen-specific IgG levels against BfrB and GrpE in rabbits (<i>p</i> < 0.05). Furthermore, these vaccines accelerated the pathological process following BCG infection. The bacterial load in nodules was notably reduced, with the BG-lentinan vaccine group exhibiting the lowest levels (<i>p</i> < 0.01). <b>Conclusions</b>: Lentinan and its combined adjuvant, lentinan/Mn(J), significantly enhance the immune response elicited by the BG tuberculosis subunit vaccine, providing effective protection.