Finally, one should consider whether, due to variable quality of JE serologic diagnostics in the pre-introduction study periods or the high prevalence of anti-JE IgM due to earlier asymptomatic infections among persons who then develop AES or viral encephalitis due to other causes, cases of childhood encephalitis that were labeled JE prior to vaccine introduction were not truly JE. The gene discussed is CD40LG; the disease is viral encephalitis.