Earlier serologic studies detected OPXV antibodies in human sera, which supplemented the diagnosis in the presence of the typical poxvirus disease symptoms, such as the presence of maculopustular rash, skin lesions, fever, lymphadenopathy, etc. While IgG ELISA was one of the most used serologic methods to detect past exposure to Mpox in humans, IgM ELISA detected more recent infections in humans. Here, CD40LG is linked to infection.