ThemostnoticIBLeconnectionofRSVinfectionswithrespiratoryinfectionsandspecificclinicalsyndromeswasdetectedininfantsupto6monthsofagewithbronchiolitisorpneumonia.Inolderinfantsorsmallchildrenthediseaseismilder.In25%ofinfectionsoftherespiratorytractRSVinfectionsaredetectable.Asre-infectionswithRSVarepossible,itisassumedthatthesepre-infectiousantibodiesareresponsibleforthemildcourseofthediseaseinadultsquitesimilartoacold.However,especiallyintheearlyyears,serumantibodiesleadnottoaneffectiveprotectionagainstinfectionsoftherespiratorytract.Therefore,thispathogenmaycausebronchiolitisorininfantsupto4monthsofagepneumonias.
Basedontheirantigenrelationship,RSVisolatescanbedifferentiatedintotwomajorgroups(AandB).Thesurfaceglycoproteinsofthevirus(theGglycoproteinandthefusionglycoprotein)causetheproductionofvirus-neutralizingantibodies.ObviouslytheGglycoproteinsofgroupsAandBareverydifferentincomparisontotheFglycoproteins.
ThecomplementbindingreactionisunsatisfactoryfortheSEROlogicaldiagnosisofRSV.EnzymeimmunoassaysareofhigherdiagnosticvaluefortheserologicaldiagnosisofRSVinfections,astheyareverysensitiveandallowthedifferentiationofantigensintothevariousimmunoglobulinclasses.InRSVinfections,itispossiblethattheIgMantibodyresponseismissingorsoweakthatareliableinterpretationoftheresultsisimpossible.ThedetectionofIgGantibodiesinasinglesampleisnoevidenceforanacuteinfectionasIgAantibodiesmaypersistmonthsandyears.ThemethodrecommendedforserologicaltestingofacuteRSVinfectionsisthedeterminationofIgGantibodiesinserumpairswithasignificanttiterrise.