Viral capsid antigen antibodies: VCA IgG (high affinity): positive response to previous EBV infection and can be positive for life; VCA IgG (low affinity): this antibody appears around 10 days after EB infection and responds to recent EB infection; VCA IgA: positive response to previous EB infection within 1 year, and there is a correlation between long-term positivity and the occurrence of nasopharyngeal cancer; VCA IgM. Positive response to acute EB infection, a more reliable indicator. Early antigen antibodies: EA IgG: positive for recent EBV infection and active viral proliferation; EA IgA: better correlation with nasopharyngeal cancer than VCA IgA. Core antigen antibodies: EBNA IgG: appears 3-4 weeks after onset, may last for life, and is a sign of previous infection. EBV DNA: A sensitive indicator of EBV infection and replication and proliferation, greater than 500 copies is significant. In addition, its value correlates with the incidence of nasopharyngeal cancer. Anisocytic lymphocytes: >10% in peripheral blood, a diagnostic reference for EB-induced infectious mononucleosis. Heterophilic agglutination test: A test for the diagnosis of EB-induced mono, appearing 1 to 2 weeks after onset and peaking at 3 to 4 weeks. A positive test has diagnostic significance, but a negative test does not exclude EB infection.