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Applied and Environmental Microbiology, January 2000, p. 213-218, Vol. 66, No. 1
Division of Molecular Virology, Baylor
College of Medicine, Houston,1 and Texas
Department of Health, Austin,4 Texas, and
Viral Gastroenteritis Section, Respiratory and Enteric Viruses
Branch, Division of Viral and Rickettsial
Diseases,2 and Foodborne and Diarrheal
Diseases Branch, Division of Bacterial and Mycotic
Diseases,3 National Center for Infectious
Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia
Received 28 June 1999/Accepted 12 October 1999
"Norwalk-like viruses" (NLVs) and hepatitis A virus (HAV) are
the most common causes of virus-mediated food-borne illness. Epidemiological investigations of outbreaks associated with these viruses have been hindered by the lack of available methods for the
detection of NLVs and HAV in foodstuffs. Although reverse transcription
(RT)-PCR methods have been useful in detecting NLVs and HAV in bivalve
mollusks implicated in outbreaks, to date such methods have not been
available for other foods. To address this need, we developed a method
to detect NLVs and HAV recovered from food samples. The method involves
washing of food samples with a guanidinium-phenol-based reagent,
extraction with chloroform, and precipitation in isopropanol. Recovered
viral RNA is amplified with HAV- or NLV-specific primers in RT-PCRs,
using a viral RNA internal standard control to identify potential
sample inhibition. By this method, 10 to 100 PCR units (estimated to be
equivalent to 102 to 103 viral genome copies)
of HAV and Norwalk virus seeded onto ham, turkey, and roast beef were
detected. The method was applied to food samples implicated in an
NLV-associated outbreak at a university cafeteria. Sliced deli ham was
positive for a genogroup II NLV as determined by using both polymerase-
and capsid-specific primers and probes. Sequence analysis of the
PCR-amplified capsid region of the genome indicated that the sequence
was identical to the sequence from virus detected in the stools of ill
students. The developed method is rapid, simple, and efficient.
0099-2240/0/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Development of Methods To Detect "Norwalk-Like
Viruses" (NLVs) and Hepatitis A Virus in Delicatessen Foods:
Application to a Food-Borne NLV Outbreak

*
Corresponding author. Mailing address: Division of
Molecular Virology, Baylor College of Medicine, 1 Baylor Plaza,
Houston, TX 77030. Phone: (713) 798-6849. Fax: (713) 798-6802. E-mail: ratmar{at}bcm.tmc.edu.
Present address: Johns Hopkins School of Hygiene and Public Health,
Department of Environmental Health Sciences, Baltimore, MD 21205.
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