Medical Microbiology

406 7 GeneralVirology

laboratorydiagnosticsarejustifiediffurthertreatmentofthepatientwould

beinfluencedbyanetiologicaldiagnosisorifaccuratediagnosticinformation

isrequiredinthecontextofanepidemicorscientificresearchandstudies.

Thereareessentiallythreedifferentmethodsusedinvirologicaldiagnos-

tics(Table 7. 5 ):

1. Virusisolationbygrowingthepathogeninacompatiblehost;usuallydone

incellcultures.

2. Directvirusdetectioninpatientmaterial;identificationofviralparticles
   usingelectronmicroscopy,viralantigenswiththemethodsofserology,
   andviralgenome(components)usingthemethodsofmolecularbiology.


3. Antibodyassayinpatientserum.
   Generalguidelinesforviraldiagnosticsarelistedbelow.Specificdetailson
   detectionandidentificationofparticularviralspeciesarediscussedinthe
   relevantsectionsofChapters 8 and 1 2.

VirusIsolationbyCulturing

Inthisapproach,thevirusisidentifiedbasedonitsinfectivityandpatho-

genicitybyinoculatingahostsusceptibleforthesuspectedvirus—inmost

casescellcultures—withthespecimenmaterial.Certainchangesobserved

intheculture(cytopathiceffect[CPE]p.392f.)indicatethepresenceofavirus.

Table 7. 5 VirologicalLaboratoryDiagnostics

Diagnostic

approach

Methods Detection/identi-

ficationof

Advantages/

disadvantages

Isolation Growingincell

cultures

Infectivity,

pathogenicity

Slowbutsensitive

method

Directdetection Electron

microscopy,EIA,

IF,hybridization,

PCR

Viralparticles,

antigens,genome

Fastmethod,but

maybelesssensitive

Serology EIA,IF,etc. Antibodies Retrospective

method

7

Kayser, Medical Microbiology © 2005 Thieme