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United States Department of Agriculture

Agricultural Research Service


item Richards, Gary

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 6/18/2008
Publication Date: 3/1/2009
Citation: Richards, G.P. 2009. AN OVERVIEW OF ENTERIC VIRUS EXTRACTION AND ASSAY METHODS. In:P.Busby (ed)., Proceedings of the 6th Int'l Conference on Molluscan Shellfish Safety, Blenheim, New Zealand. pp.111-118.

Interpretive Summary:

Technical Abstract: Enteric viruses, particularly norovirus and hepatitis A virus, are major contaminants of molluscan shellfish, leading to outbreaks of viral illness. A host of procedures have been developed for the extraction and assay of viruses from shellfish. Early extraction and assay methods focused on the detection of vaccine strains of poliovirus as a possible indicator for other enteric viral pathogens. Plaque and cytopathogenicity assays, the radioimmunofocus assay, and luminescent immunofocus assay were developed to detect viruses capable of replication in cell cultures. The advent of molecular biology opened the way for reverse transcription – polymerase chain reaction (RT-PCR) and quantitative RT-PCR. In spite of the advances made, the extraction procedures are time-consuming and complex. Assay methods suffer from limitations including the presence of inhibitory compounds in the extracts and the inability to differentiate infectious from inactivated viruses using molecular methods. Recent advances in the propagation of noroviruses may ultimately make RT-PCR methods obsolete. This presentation describes: a) general procedures for virus extraction from shellfish, b) cell-culture-based and molecular methods for virus assay, c) limitations in the procedures, d) factors important to the interpretation of results, e) harmonization of methods, f) new discoveries that may change the way shellfish are analyzed, and g) future directions for research.

Last Modified: 10/17/2017
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