CD40LG and infectious mononucleosis: Tests for herpes simplex virus (HSV) I and II immunoglobulin (IgM) antibody, infectious mononucleosis, rubeola IgM, urine legionella antigen, hepatitis A, B, and C panel, and CMV DNA polymerase chain reaction and IgM antibody were all negative, as well as human immunodeficiency virus (HIV) 1 and 2 antigen/antibody fourth generation test, which was nonreactive, and corona virus 2019 (COVID-19) SARS-CoV-2 was undetected (Table 1).