Serological Tests for Infectious
Mononucleosis (IM)
Immunology Review 402
Specificity
Occurrence
Tests
HETEROPHILE ANTIBODIES*
Nonspecific abs that agglutinate horse, sheep, &
bovine RBCs. Heterophile abs are abs that react
with similar ags from different species.
90% of patients develop in 1st month of illness. Can
persist for 1 yr. Neg in 10% of adults & up to 50% of
children with IM. If symptomatic & heterophile neg,
test for EBV-specific abs.
Rapid latex agglutination, solid-phase immunoas-
says. Ag is purified bovine RBC extract. Screening
tests.
EBV-SPECIFIC ANTIBODIES
Specific abs against Epstein-Barr virus (EBV) ags present in differ-
ent phases of infection—early: early ag (EA), late: viral capsid ag
(VCA), latent: EBV nuclear ag (EBNA).
Anti-VCA IgM appears at onset of symptoms, disappears in 3 mo.
Anti-VCA IgG appears at onset of symptoms, persists for life.
Anti-EBNA present during convalescence.
Acute infection: Anti-VCA IgM, anti-VCA IgG, anti-EA.
Past infection: Anti-EBNA, anti-VCA IgG, neg anti-VCA IgM.
Indirect immunofluorescent assays (IFA), ELISA, chemilumines-
cent assays. IFA is gold standard but time consuming & harder to
interpret. Molecular tests can be used for immunocompromised
patients who don’t produce abs.
