Advax4 delta inulin combination adjuvant together with ECMX, a fusion construct of four protective mTB antigens, induces a potent Th1 immune response and protects mice against Mycobacterium tuberculosis infection

Abstract

Tuberculosis (TB) remains a main public health concern and 10.4 million new cases occurred in 2015 around the world. BCG is the only approved vaccine against TB, but has variable efficacy and new vaccines are needed. We developed two new mTB vaccine candidates based on the recombinant fusion proteins, rCMX and rECMX formulated with Advax4, a new combination adjuvant combining delta inulin, CpG oligonucleotide and murabutide. BALB/c mice were immunized three times intramuscularly with these vaccine formulations. Injection of Advax4 alone increased the percentage of lymphatic endothelial cells and activated macrophages (F480/CD11b) in the draining lymph nodes consistent with a chemotactic adjuvant effect. Advax4+CMX and Advax4+ECMX induced the highest levels of IgG1 and IgG2a antibodies against rCMX and rECMX, respectively. Immunized mice challenged with Mycobacterium tuberculosis (Mtb) had increased vaccine-specific Th1 responses in the lungs together with reduced Mtb - associated alveolar damage, although only the Advax4+ECMX vaccine demonstrated significant reduction of lung bacterial load. This study confirmed Advax4+ECMX as a potential TB vaccine candidate, with potential for further optimization and clinical development.

Specific T cell induction using iron oxide based nanoparticles as subunit vaccine adjuvant

“…CMX is capable of inducing IL-6 and TGF-b expression in macrophages in vitro 25 ; however, when used alone, it cannot generate an adaptive immune response. 55 This observation is in agreement with the literature showing that protein alone cannot efficiently generate an adaptive immune response. 56 CMX was used by de Sousa et al (2010) in a formulation with CpG/ DNA and liposomes and efficiently induced a Th1 response, 21 which is important for protection against TB.…”

“…Moreover, the lesions caused by intravenous infection are similar to those caused by aerosol infection; thus, the host-pathogen interactions are conserved. 23,24,55 Finally, for the first time, this study demonstrates that MnFe 2 O 4 NPs in a vaccine formulation can generate cellular immune responses. The formulation could generate Th1 and, most prominently, Tc1 (CD8) responses that could be recalled upon TB infection and could help in protection against the bacteria, as demonstrated by our evaluation of the total immune response present in the lungs and spleen.…”

Developing New Anti-Tuberculosis Vaccines: Focus on Adjuvants

“…Advax ® was also formulated with CpG and a muramyl dipeptide, murabutide, in a vaccine candidate with recombinant fusion proteins. This adjuvant system combines, besides the inulin, a TLR9 agonist, which is the CpG and a NOD-like receptor 2 agonist, the murabutide peptide [ 72 ]. In this study, the mice immunized intramuscularly with the combination of fusion protein and adjuvant system showed antigen-specific antibodies, namely IgG2a and IgG1, at higher levels than the other groups, with a bias to IgG2a which suggests a Th1 type of response [ 72 ].…”

“…This adjuvant system combines, besides the inulin, a TLR9 agonist, which is the CpG and a NOD-like receptor 2 agonist, the murabutide peptide [ 72 ]. In this study, the mice immunized intramuscularly with the combination of fusion protein and adjuvant system showed antigen-specific antibodies, namely IgG2a and IgG1, at higher levels than the other groups, with a bias to IgG2a which suggests a Th1 type of response [ 72 ]. Moreover, the mice in this group also had decreased lung inflammation after challenge with Mtb [ 72 ].…”

“…In this study, the mice immunized intramuscularly with the combination of fusion protein and adjuvant system showed antigen-specific antibodies, namely IgG2a and IgG1, at higher levels than the other groups, with a bias to IgG2a which suggests a Th1 type of response [ 72 ]. Moreover, the mice in this group also had decreased lung inflammation after challenge with Mtb [ 72 ]. Both of these studies show the potential of Advax ® and possibly other inulin-based adjuvants in TB vaccine formulations.…”