The main problem with cell culture is the long period (up to 4 weeks) required for a result to be available. Also, the sensitivity is often poor and depends on many factors, such as the condition of the specimen, and the condition of the cell sheet. Cell cultures are also very susceptible to bacterial contamination and toxic substances in the specimen. Lastly, many viruses will not grow in cell culture at all e.g. Hepatitis B and C, Diarrhoeal viruses, parvovirus etc.
Rapid Culture Techniques
Rapid culture techniques are available
whereby viral antigens are detected 2 to 4 days after
inoculation. Examples of rapid culture techniques include
shell vial cultures and the CMV DEAFF test. In the CMV DEAFF
test, the cell sheet is grown on individual cover slips in a
plastic bottle. After inoculation, the bottle then is spun
at a low speed for one hour (to speed up the adsorption of
the virus) and then incubated for 2 to 4 days. The cover
slip is then taken out and examined for the presence of CMV
early antigens by immunofluorescence.
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Left: Haemadsorption of red blood cells onto the surface of a cell sheet infected by mumps virus. Also note the presence of syncytia which is indistinguishable from that of RSV (Courtesy of Linda Stannard, University of Cape Town). Right: Positive CMV DEAFF test. (Virology Laboratory, Yale-New Haven Hospital)
The role of cell culture (both conventional and rapid techniques) in the diagnosis of viral infections is being increasingly challenged by rapid diagnostic methods i.e. antigen detection and molecular methods. Therefore, the role of cell culture is expected to decline in future and is likely to be restricted to large central laboratories.