MPL adjuvant in the form of AS04 mimics a Toll-like receptor 4 agonist providing direct stimulation of antigen presenting cells, pronounced cellular and humoral immune responses, and long lasting antibody responses (179).The Hepavax-Gene (thiomersal free) and Engerix B are non-infectious recombinant hepatitis B vaccines that contain highly purified HBsAg. Here, TLR4 is linked to hepatitis B virus infection.