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Chapter 50 : Sampling Viruses from Soil
This chapter focuses on the methodology used to detect animal viruses in samples of soil. This methodology generally relies on elution and subsequent concentration of viruses from the soil, after which either cytopathogenicity or plaque formation assays are used to detect the viruses. These assays are based on the use of cultured animal cells as hosts for viral replication. The chapter also describes the use of plaque formation methodology to detect bacteriophages, viruses which infect bacteria. Other types of assay procedures, such as those based on the PCR, have also been developed to detect viruses in soil samples. Many different types of apparatus can be used to collect soil samples. These range from spoons and spatulas to shovels and powered augers. The available options for suitable sample containers include wide-mouthed screw-cap plastic jars and zipper closure plastic bags. Soil samples should be kept chilled to reduce thermal inactivation of the viruses. Bacteriophages can be detected by direct assay of soil suspensions using a plaque formation technique. If the presence of soil particles in the assay causes a problem, either because the resulting turbidity obscures assessment of the results or the number of contaminating soil bacteria and fungi carried along with the soil particles complicates plaque enumeration, then the bacteriophages can be eluted from the soil particles and the eluate can be assayed.