Epstein-Barr Virus (EBV) Nuclear Antigen Antibodies, IgG

Epstein-Barr Virus (EBV) Nuclear Antigen Antibodies, IgG—also referred to as EBNA IgG or anti-EBNA IgG—are used with complementary EBV serologic markers to aid diagnosis and stage infection. EBNA IgG is generally absent during acute primary infection, appears approximately 2–4 months after the initial clinical presentation, and typically remains detectable for life, supporting evidence of prior infection or latency. Serologic patterns that include viral capsid antigen (VCA), early antigen (EA), and EBNA help differentiate acute, recent, past, and latent/reactivated infection; however, a single antibody result is not diagnostic in isolation. False-positive results occur, and about 5%–10% of infected individuals may never develop EBNA IgG. EBV serology may also contribute to the clinical assessment of EBV-associated conditions (eg, certain lymphomas and nasopharyngeal carcinoma), but it does not establish these diagnoses.

Epstein–Barr virus (human herpesvirus 4) primarily targets B lymphocytes and is spread through saliva; by adulthood, approximately 95% of individuals are seropositive worldwide. Primary infection ranges from asymptomatic illness to infectious mononucleosis, which follows an incubation of 4–6 weeks with prodromal myalgias and fatigue and then fever, pharyngitis, generalized lymphadenopathy, splenomegaly, and occasionally hepatomegaly and rash. Atypical lymphocytosis (>10%) and transient increases in aminotransferases are common laboratory findings. EBV establishes latency in B cells with potential for clinically silent reactivation. In the setting of immunodeficiency or iatrogenic immunosuppression, EBV is associated with B‑cell lymphomas and other EBV‑related neoplasms, including Burkitt lymphoma, Hodgkin lymphoma, nasopharyngeal carcinoma, and oral hairy leukoplakia. Key antigens used in EBV serology include the viral capsid antigen (VCA), early antigen (EA), and nuclear antigen (EBNA). Anti‑EBNA IgG is uncommon during acute primary infection, emerges during convalescence, reaches a stable plateau by 3–12 months, and usually persists for life. A serologic pattern of positive VCA IgM with absent EBNA IgG supports primary infection, whereas the presence of EBNA IgG together with elevated EA IgG may be seen with reactivation. Results require integration with clinical information and other laboratory data. The assay is qualitative; values above the cutoff are not proportional to antibody concentration.