Chemistry of Plant Viruses

Abstract

Before any chemical analyses can be made of a plant virus, or indeed any virus, it is necessary to free it from the host cell materials, and we have already discussed some of the methods for doing this in Chapter Four. However, not all plant viruses are amenable to these purification techniques and out of the 300 or more plant viruses already described only about 10 per cent have been isolated in sufficient quantities for chemical analysis. As we have previously pointed out in Chapter Four, the essential conditions for purification are high concentration of virus in the host plant, not less than 2 mg per litre, stability of the virus under the necessary chemical treatments, suitability of the host plant, i.e. absence of tannins, mucilage, etc. in the plant sap, and possibly also a difference in size of the virus particles from that of the cell components.