Serological testing for these infections has well-documented limitations: antibodies to immunoglobulin M (IgM) may not be detectable early in the course of infection; a rise in immunoglobulin G (IgG) between acute and convalescent samples can only provide a retrospective diagnosis; and anti-flavivirus antibodies may cross-react with one another [20]. The gene discussed is CD40LG; the disease is infection.