Viral capsid antigen (VCA). Anti-VCA IgM appears early in EBV infection and usually disappears within four to six weeks. · Early antigen (EA) Anti-EA IgG appears ...SkipdirectlytositecontentSkipdirectlytopageoptionsSkipdirectlytoA-ZlinkEpstein-BarrVirusandInfectiousMononucleosisSectionNavigationCDCHomeFacebookTwitterLinkedInSyndicateLaboratoryTestingMinusRelatedPagesEpstein-Barrvirus(EBV),alsoknownashumanherpesvirus4,isagammaherpesvirusthatoccursonlyinhumans.LaboratorytestingcanhelpdistinguishwhethersomeoneissusceptibletoEBVinfectionorhasarecentorpastinfection.HealthcareproviderscantestforantibodiestothefollowingEBV-associatedantigens:ThisphotomicrographdepictsleukemiacellsthatcontainEpstein-BarrvirususinganFAstainingtechnique.Viralcapsidantigen(VCA)Anti-VCAIgMappearsearlyinEBVinfectionandusuallydisappearswithinfourtosixweeks.Anti-VCAIgGappearsintheacutephaseofEBVinfection,peaksattwotofourweeksafteronset,declinesslightlythenpersistsfortherestofaperson’slife.Earlyantigen(EA)Anti-EAIgGappearsintheacutephaseofillnessandgenerallyfallstoundetectablelevelsafterthreetosixmonths.Inmanypeople,detectionofantibodytoEAisasignofactiveinfection.However,20%ofhealthypeoplemayhaveantibodiesagainstEAforyears.EBVnuclearantigen(EBNA)AntibodytoEBNA,determinedbythestandardimmunofluorescenttest,isnotseenintheacutephaseofEBVinfectionbutslowlyappearstwotofourmonthsafteronsetofsymptomsandpersistsfortherestofaperson’slife.OtherEBNAenzymeimmunoassaysmayreportfalsepositiveresults.MonospottestTheMonospottestisnotrecommendedforgeneraluse.TheantibodiesdetectedbyMonospotcanbecausedbyconditionsotherthaninfectiousmononucleosis.Moreover,studieshaveshownthattheMonospotproducesbothfalsepositiveandfalsenegativeresults.Forexample,theheterophileantibodiesdetectedbyMonospotareoftennotpresentinchildrenwithinfectiousmononucleosis.Atbest,theMonospottestmayindicatethatapersonhasatypicalcaseofinfectiousmononucleosis,butdoesnotconfirmthepresenceofEBVinfection.InterpretationofEBVAntibodyTestsEBVantibodytestsarenot