[Characteristics of immune response induced by mucosal immunization with recombinant adenovirus of Mycobacterium...

Objective The prevalence of drug-resistant Mycobacterium tuberculosis (Mtb) strains is exacerbating the global burden of tuberculosis (TB), highlighting the urgent need for new treatment strategies for TB. Methods The recombinant adenovirus vaccine expressing cyclic di-adenosine monophosphate (c-di-AMP) phosphodiesterase B (CnpB) (rAd-CnpB), was administered to normal mice via mucosal immunization, either alone or in combination with drug therapy, to treat Mtb respiratory infections in mice.Enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of antibodies in serum and bronchoalveolar lavage fluid (BALF). Real-time quantitative PCR was performed to assess the transcription levels of cytokines interferon γ(IFN-γ) and interleukin 10(IL-10) in mouse lungs. Flow cytometry was used to determine the proportions of CD4⁺ and CD8⁺ T cell subsets in the lungs and spleens. ELISA was employed to measure the levels of cytokines IFN-γ, IL-2, IL-10, inflammatory factors IL-6, and tumor necrosis factor α (TNF-α) secreted by spleen cells following antigen stimulation. The bacteria loads in the lungs and spleens of Mtb-infected mice were enumerated by plate counting methods. Resluts Intranasal immunization with rAd-CnpB induced high titers of IgG in mouse serum and the production of IgG and IgA in BALF, along with alterations in T lymphocyte subsets in the lungs and spleens. Administration of rAd-CnpB, either alone or in combination with drugs, to Mtb-infected mice significantly increased serum IgG levels as well as IgA and IgG levels in BALF. rAd-CnpB immunization promoted the secretion of CnpB-specific cytokines and inflammatory factors by splenocytes in Mtb-infected mice. However, rAd-CnpB immunotherapy, either alone or combined with drugs, did not significantly affect the bacterial loads in the lungs and spleens of mice with Mtb respiratory infections. Conclusion Mucosal immunization with rAd-CnpB induced significant mucosal, humoral and cellular immune responses in mice, and significantly enhanced CnpB-specific cellular immune responses in Mtb-infected mice.