Coated Bacterial Vaccine: A new approach for antigen display on
bacterial surface
Abstract
Bacterial vaccines using recombinant antigens displayed on the bacterial
surface represent a major advancement in vaccine development. This
approach leverages bacteria’s natural ability to induce immune responses
while improving vaccine targeting and efficacy. Existing platforms, such
as live bacterial vaccines, inactivated bacterial vaccines, and
bacterial-like particles (BLPs), face challenges like genetic
modifications, antigen dilution, and degradation. To address these
limitations, a novel system called Coated Bacterial Vaccine (CBV) is
proposed, combining the benefits of inactivated bacterial vaccines and
BLPs technology. The recombinant antigen is fused to the
carboxy-terminal cell wall-binding domain of the Lactobacillus SlpA
protein (dSLPA) and anchored in vitro on chemically inactivated
Gram-positive bacteria. To validate this system, CBVs were created using
inactivated B. subtilis 15245 and the TTFC antigen, a fragment of
tetanus toxin (TeTx) fused with dSLPA. CBVs were used to immunize BALB/c
mice, and anti-TTFC IgG antibodies were measured. Mice were then
challenged with TeTx to assess the protective effects of CBVs. Results
showed a 100% survival rate in vaccinated mice after TeTx challenge,
driven by a robust anti-TTFC IgG response, particularly elevated IgG1
levels. Additionally, macrophage stimulation assays showed increased
mRNA levels for IL-1β, IL-6, and IL-10, along with significant IL-6
secretion. These findings demonstrate that CBVs based on B. subtilis can
provide effective immune protection through a Th2-polarized response,
highlighting the potential of CBVs as a versatile tool for developing
new-generation vaccines.