Viral serology tests are blood tests used to identify past or present infections with viruses. These tests detect antibodies, which are proteins produced by the immune system in response to a viral infection. Different serological tests are available for various viruses. Common Viral Serology Tests: Hepatitis A, B, and C: To detect current or past infections with hepatitis viruses. HIV: To detect antibodies to the human immunodeficiency virus. Herpes simplex virus (HSV): To detect antibodies to HSV-1 (oral herpes) and HSV-2 (genital herpes). Cytomegalovirus (CMV): To detect antibodies to CMV, a common virus that can cause problems for people with weakened immune systems or pregnant women. Epstein-Barr virus (EBV): To detect antibodies to EBV, the virus that causes mononucleosis (mono).