Food-borne Virus: Detection in a Model System
AUTOR(ES)
Herrmann, John E.
RESUMO
The purpose of this study was to develop methods for detection and quantitation of food-borne virus. Samples (25 g) of cottage cheese, contaminated with various quantities of coxsackievirus type A9, comprised the model system. Two of the methods presented have at least a 50% probability of detecting virus at levels below 5 plaque-forming units/25-g sample. Noteworthy aspects of these methods include use of a glycine-NaOH buffer (pH 8.8) containing approximately 1 m MgCl2 as the diluent in which the sample is slurried, treatment of the slurry with Freon TF and bentonite to facilitate centrifuge clarification, and concentration of the clarified sample extract by a two-stage process employing polyethylene glycol followed by ultracentrifugation. Virus in the final 0.5-ml sample concentrate was detected and quantitated by the plaque technique in rhesus monkey kidney cell cultures. Processing of the sample requires approximately 2 days, and the inoculated cultures may have to be observed for as long as 7 days thereafter. If these levels of sensitivity are desired, and if 12 samples per day are tested on a routine basis, the cost savings achieved by employing these methods rather than testing sample extracts without concentration may range from 75 to 90%.
