Methods for Diagnosis of Viral Infections Clinical Microbiology Review 284
Cytology/histology
Electron microscopy
Direct fluorescent antibody stain
Antigen detection
Cell culture
Shell vial culture
Molecular methods
Serology
Microscopic examination of specimen for viral cytopathic effect (CPE).
Rarely used. Labor intensive, expensive.
Fluorescent-labeled antibody added to patient cells fixed to slide. If viral antigen present,
antibody binds. Fluorescence seen with fluorescent microscope.
Solid-phase & membrane ELISAs.
Different viruses grow in different cell lines. Growth may take 1–28 days. Examine microscopi-
cally for cytopathic effects (CPE): cell rounding, clumping, vacuolation, granulation, giant multi-
nucleate cells, cell fusion, syncytial formation, cell lysis, plaques (groups of killed cells), inclusion
bodies. Not all viruses produce CPE. Immunofluorescent stains may be used for confirmation.
Rapid modification of conventional cell culture. Detection in 1–2 days. Specimen centrifuged
onto monolayer of cells growing on coverslip. Coverslips stained with viral-specific immunofluo-
rescent conjugate. Used primarily for viruses that are slow to produce CPE.
PCR, real-time PCR, branched DNA, nucleic acid hybridization. Faster & more sensitive than cell
culture. Can detect viruses that can’t be cultured, multiple viruses simultaneously.
Detects antibodies in serum. Useful in evaluating immune status or diagnosing viral infections
where culture is difficult or impossible. Presence of antibodies isn’t always indicative of current
infection.
