COMMON DIAGNOSTIC TECHNIQUES

Electron microscopy (EM)

Astroviruses can be detected in human feces through negative staining and EM since affected patients usually shed large numbers of viral particles. However, accurate identification of the virus may be difficult using this method because only 10% of the particles in a given sample may show the distinguishing astrovirus surface star. For example, initial examination based on EM morphology of the virus associated with the 1978 outbreak of gastroenteritis in Marin County, CA, revealed the virus to be "Norwalk-like." Later analyses demonstrated that the virus was actually astrovirus serotype 5.

Enzyme Immunoassay (EIA)

An EIA using a monoclonal antibody for viral antigen capture and polyclonal antiserum as the detector antibody is employed in studies where rapid detection of astrovirus antigen is needed.

Reverse transcriptase-polymerase chain reaction (RT-PCR)

The complete sequencing of three strains of astrovirus enabled detection of the virus using molecular probes and RT-PCR. Primers derived from the 3' end of the genome or from the RNA-dependent RNA polymerase motif may be used to amplify various human serotypes.