title: Prevalence of primary versus reactivated Epstein-Barr virus infection in patients with VCA IgG-, VCA IgM- and EBNA-1-antibodies and suspected infectious mononucleosis.
abstract: BACKGROUND
  In Epstein-Barr virus (EBV) infection, IgG- and IgM-antibodies to viral capsid antigen (VCA) and IgG-antibodies to Epstein-Barr nuclear antigen 1 (EBNA-1) can occur simultaneously both in late primary infection and during subclinical viral reactivation in immunocompetent persons, and the differential diagnosis is of importance.
  
  
  OBJECTIVE
  To study the prevalence of primary infection and serological reactivation in patients with suspected primary EBV infection and with all three parameters present.
  
  
  METHODS
  Fifty serum samples from 43 consecutive patients referred for suspected infectious mononucleosis and positive for VCA IgG-, VCA IgM- and EBNA-1-antibodies by EIA, were tested for IgG-antibody avidity with an EBV IgG immunoblot. Sera were also tested for heterophile antibodies (HA). To verify the presence of IgM-antibodies an EBV IgM immunoblot was performed when high-avidity IgG-antibodies were found.
  
  
  CONCLUSIONS
  Of 43 patients with suspected primary EBV infection and VCA IgG-, VCA IgM- and EBNA-1-antibodies present, only 18 patients (42%) had a late primary infection. Twenty-one patients (49%) had high-avidity IgG-antibodies, indicating an IgM response due to reactivation, thus suggesting other causes for their symptoms. In 10 of these 21 patients the presence of IgM-antibodies was confirmed by immunoblot, indicating reactivation as a cause of IgM-antibodies in at least 23% of the 43 patients studied. Of 18 patients with primary infection, HA were detected in 16 (94%) of 17 patients tested. Only one (5%) of the patients with high-avidity antibodies had HA. Absence of HA in patients with this serological pattern is therefore a good indicator of reactivation, and conversely, the presence of HA is a good indicator of primary infection. In HA negative patients, avidity testing could be used for differential diagnosis.
authors.affiliation: Department of Microbiology and Immunology, The Gade Institute, Haukeland University Hospital, N-5021 Bergen, Norway. tone.wikene.nystad@helse-bergen.no <tone.wikene.nystad@helse-bergen.no>
authors.forename: Tone Wikene
authors.initials: TW
authors.lastname: Nystad
authors.forename: Helge
authors.initials: H
authors.lastname: Myrmel
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000910:Antibodies, Heterophile / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood*; D000915:Antibody Affinity; D000956:Antigens, Viral / Q000276:immunology*; D036022:Capsid Proteins / Q000276:immunology*; D002648:Child; D003430:Cross-Sectional Studies; D003937:Diagnosis, Differential; D020031:Epstein-Barr Virus Infections / Q000453:epidemiology / Q000276:immunology*; D019309:Epstein-Barr Virus Nuclear Antigens / Q000276:immunology*; D004854:Herpesvirus 4, Human / Q000276:immunology; D006801:Humans; D015151:Immunoblotting; D007124:Immunoenzyme Techniques; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D007244:Infectious Mononucleosis / Q000453:epidemiology / Q000276:immunology*; D008875:Middle Aged; D015995:Prevalence; D014775:Virus Activation / Q000276:immunology*
chemical_list: D000910:Antibodies, Heterophile; D000914:Antibodies, Viral; D000956:Antigens, Viral; D036022:Capsid Proteins; D019309:Epstein-Barr Virus Nuclear Antigens; C041788:Epstein-Barr viral capsid antigen; D007074:Immunoglobulin G; D007075:Immunoglobulin M; C417029:EBV-encoded nuclear antigen 1