Abstract
Toll-like receptors (TLRs) form a key bridge between the innate and adaptive immune systems. The lipopeptide based TLR2 agonists such as Pam(2)CSK(4) are promising vaccine adjuvants but drawbacks include its surfactant like nature and cumbersome synthesis. Although the TLR2 activity of Pam(2)CS-OMe is commensurate with Pam(2)CSK(4), its water solubility is much less, rendering it ineffective for clinical use. In the present investigation, we designed a synthesis pathway for a novel water-soluble TLR2-active analogue, Pam(2)CS-DMAPA (13), which enhanced the immunogenicity of recombinant SARS-CoV2 and hepatitis B antigens in mice. Co-formulation of compound 13 with 2 % aluminium hydroxide gel led to a further significant improvement in vaccine immunogenicity. This synthetically simpler compound 13 was water soluble and equally potent to Pam(2)CSK(4) adjuvant, but was superior in terms of manufacturing simplicity and scalability. This makes compound 13 a promising TLR2 targeted adjuvant for further development.