TLR4 and herpes zoster: The adjuvant recombinant zoster vaccine (Shingrix, GSK plc, London, UK) contains a recombinant glycoprotein E (gE) and AS01B Adjuvant System, consisting of a liposomal formulation of monophosphoryl lipid A (MPL), a toll-like receptor 4 (TLR4) agonist, and QS-21, a purified plant extract.