Investigating the affinity of poly tert-butyl acrylate toward Toll-Like Receptor 2

Abstract

Despite the high safety profile of peptide-based vaccines over conventional counterparts, the inability of small peptides to produce a strong immune response represents the main obstacle for the development of these types of vaccines. Introducing a self-adjuvanting moiety such as poly tert-butyl acrylate can overcome this problem. However, the mode of action of this polymer to produce the desired humoral and/or cellular immune response is still unknown. An AlphaScreen assay along with the cell-free expression technique were employed to evaluate the affinity of this polymer toward toll-like receptor 2 (TLR2) for stimulation of innate immunity. In this study, B-cell epitope, J14, derived from the M protein of group A streptococcus (GAS) was used in conjugation with the poly tert-butyl acrylate as well as a biotin moiety. Pam2Cys analogue, the potent TLR2 agonist, was synthesized and used as a positive control in this work. The AlphaScreen assay showed the inability of polymer to bind to TLR2, while the Pam2Cys displayed very strong binding to TLR2 as expected. This result indicated that poly tert-butyl acrylate does not express its immunogenic effects through recognition by TLR2 and therefore further studies are required to determine its mode of action.

Keywords

• TLR2 agonists| poly <em>tert</em>-butyl acrylate| vaccines| AlphaScreen assay| adjuvant