
Full text loading...
Category: Applied and Industrial Microbiology; Food Microbiology
Historic Overview of Food Virology, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555815738/9781555814649_Chap01-1.gif /docserver/preview/fulltext/10.1128/9781555815738/9781555814649_Chap01-2.gifAbstract:
The earliest approaches to detection of viruses in water and in food were derived from those used in diagnostic clinical virology. Early detection methods were based on demonstrable infection of a susceptible host system, ideally a cell culture. Media for primary cell cultures often comprised a balanced salt solution plus an enzymatic hydrolysate of lactalbumin and some blood serum. Virus replication in cell cultures was often demonstrated with the aid of a microscope: death of host cells maintained in fluid medium was called the cytopathic effect. Characterization of the viruses of interest was complicated by the lack of laboratory hosts. Eventually, viruses were classified as having RNA or DNA, as having or lacking a lipid-containing envelope, and by size category. Detection of viruses in food extracts originally implied the use of primary monkey kidney (PMK) cell cultures, as was also done for diagnostic purposes. Propagation of viruses in cell culture and development of the plaque technique introduced much more quantitative precision into inactivation experiments. The bovine spongiform encephalopathy (BSE) epidemic appears to have resulted from a change in the rendering process used in the United Kingdom. The BSE infective agent could be detected in the brain, spinal cord, retina, trigeminal and dorsal root ganglia, tonsils, and distal ileum of symptomatic BSE-infected cattle; but extensive tests have failed to detect it in muscle meat or in milk. Most food-borne viruses are human specific, so this has generally entailed the use of human volunteers.
Full text loading...
Overview of the steps involved in detecting food-borne viruses. RT-PCR, reverse transcription-PCR.
Peroral infectious-dose study, ca. 1977. Porcine subject is shown with the author; two isolation units are visible at the rear.
Fecal-oral transmission cycle in the barrio of Belen, Iquitos, Peru. The photograph shows a family home on a community waterway; the household latrine overhangs the water at left, and a family member is washing dinner dishes in the waterway at right. (photo by Stewart Oakley, California State University, Chico; reprinted with permission.)