Typically, IgM is the first immunoglobulin isotype produced by the humoral system in response to infection; however, HCV-specific IgM has not proved a good marker of acute HCV infection as HCV-specific IgM is readily detected in chronically infected patients (96, 97), and HCV-specific IgM and IgG are both almost simultaneously detected in acute infection (98, 99). Here, CD40LG is linked to infection.