In addition, serologic tests including antibodies to a host of viruses have consistently proven noncontributory and no viral particles have been identified ultrastructurally.
Depending on the virus, the plaque forming units are measured by microscopic observation, fluorescent antibodies or specific dyes that react with infected cells.
Therefore, these tests are useful for diagnosing infectious mononucleosis in people with highly suggestive symptoms and a negative heterophile antibody test.