CD40LG and tick-borne encephalitis: Ten non-TBE patients had a false-reactive VirClia IgM serum sample at admission, four with concurrent reactivity in the ReaScan IgM, of which one case was due to an acute Epstein–Barr virus infection, one had a recent TBE immunization (first dose), one was a case of human herpesvirus 6 meningitis and, finally, one was a child with aseptic meningitis without any identified causative agent.