Methods for Virus Recovery from Solids

Much work is still needed before one single method can be selected which ensures reliable quantitative methodology. The various types of solids and the composition of the samples influence the results and there is no technique available today which is 100% efficient under varied circumstances. Negative findings may be misleading, because there is no guarantee that the virus cultivation system employed will reveal all the virus types present in the sample. For some sludges it is possible to detect viruses by direct inoculation in cell cultures. Such a method may give 10-50% recovery, essentially depending on a balance between the cell-toxicity of the samples, the tenacity of the virus to stick to the solids and the care given the cell cultures. In most methods viruses are extracted from the sample either by elution by high pH (8.5-11.5), by proteinaceous media, with chelating agents, agitation with solvents or by sonication. Adsorption to polyelectrolytes or precipitation at low pH, in both cases followed by elution by means of glycine, trisbuffer with EDTA, or beef extract has given good recovery from seeded samples and positive results from field work. Decontamination of samples is carried out in various ways.