APC targeting enhances immunogenicity of a novel multistage Fc-fusion tuberculosis vaccine in mice

Abstract

Numerous studies have demonstrated that targeting immunogens to FcγR on antigen-presenting cells (APCs) can selectively uptake and increase cellular immunity in vitro and in vivo. Therefore, the present study was conducted to evaluate immunogenicity of a novel multistage tuberculosis vaccine, a combination of an early and a dormant immunogenic protein, ESAT6 and HspX, fused to Fcγ2a fragment of mouse IgG2a to target all forms of tuberculosis. Codon-optimized genes consisting of ESAT6, a linker, and HspX fused either to mouse Fcγ2a (ESAT6:HspX:mFcγ2a) or 6× His-tag (ESAT6:HspX:His) were synthesized. The resulting proteins were then produced in Pichia pastoris. The fusion proteins were separately emulsified in dimethyldioctadecylammonium bromide(DDA)-trehalose-6,6-dibehenate(TDB) adjuvant, and their immunogenicity with and without bacille Calmette-Guérin (BCG) was assessed in C57BL/6 mice. Th1, Th2, Th17, and T-reg cytokine patterns were evaluated using the ELISA method. Both multistage vaccines induced very strong IL-12 and IFN-γ secretion from splenic cells; the Fc-tagged subunit vaccine induced a more effective Th1 immune response (IFN-γ, 910 pg/mL, and IL-12, 854 pg/mL) with a very low increase in IL-17 (∼0.1 pg/mL) and IL-4 (37 pg/mL) and a mild increase in TGF-β (543 pg/mL) compared to the BCG or ESAT6:HspX:His primed and boosted groups. The production of IFN-γ to ESAT6:HspX:Fcγ2a was very consistent and showed an increasing trend for IL-12 compared to the BCG or ESAT6:HspX:His primed and boosted groups. Fcγ2a used as a delivery vehicle supported the idea of selective uptake, inducing cross-presentation and forming a proper anti-tuberculosis response in context of Th1/Th2 and Th17/T-reg balances, which is important for protection and prevention of damage.

Role of Interferons in the Development of Diagnostics, Vaccines, and Therapy for Tuberculosis

“…IgG immunocomplexes containing Mtb antigens or IgG Fc fusions with multistage antigens from Mtb, aimed to increase the interaction with APCs, have been tested in mice which induced protection associated with increase of IFN- γ production [105, 106]. …”

Game Theory Applications in Host-Microbe Interactions: Mycobacterium tuberculosis infection as an example

“…According to the current results, it can be expected that, in the presence of high levels of IDO expression, as an inducing factor for Treg polarization, TGF-β production will also increase significantly, but in gene expression data, this assumption did not meet this status (CI=90%, p=0.1). Of note, patients in this study had no immuno-compromising conditions 16 .…”

“…The lower levels of IDO and TGF-β can be in favour of the host, in clearing the infection. As previously mentioned, IL-10 and TGF-β are also important anti-inflammatory cytokines, modulating immune responses 16 . Appropriate amounts of TGF-β and IL-10 (like medium level in latency strategies) in the Mtb -infected organs are vital, for balancing the Th1 protective response and preventing Th1 hypersensitivity (DTH) reactions, by suppressing the intensity of this response to bacteria.…”

“…Appropriate amounts of TGF-β and IL-10 (like medium level in latency strategies) in the Mtb -infected organs are vital, for balancing the Th1 protective response and preventing Th1 hypersensitivity (DTH) reactions, by suppressing the intensity of this response to bacteria. Thus, in Mtb infection, the importance of IL-10 and TGF-β may be double-edged 16 . High expression of TGF-β and IDO is a non-credible strategy that is excluded in this model, since either dampening the host’s inflammatory response or limiting the Th1 appropriate response goes toward immuno-compromise, which may allow reactivation and dissemination of infection to an active TB or reactivation of a latent status.…”

Isolation and identification of Nontuberculous mycobacteria from environmental water samples in the northeast of Iran

“…The importance of mycobacterial studies can be considered from multiple angles. The rising prevalence of infection with these bacteria is one of the severe problems facing the health systems worldwide and increases the importance of studying and tracing them in resource extractions and water distribution networks [7,8] . Unfortunately, due to lack of access to advanced diagnostic facilities and the use of traditional methods, many of these mycobacterial infections are not recognized, or are treated as tuberculosis because of their similarity with Mycobacterium tuberculosis.…”