Chapter VI - The Chemical Basis of the Infectivity of Tobacco Mosaic Virus and Other Plant Viruses

Abstract

Publisher Summary This chapter discusses the chemical basis of the infectivity of tobacco mosaic virus (TMV) and other plant viruses. The plant viruses consist only of nucleic acid and protein, while animal viruses range from this simplest composition to considerably more complex compositions. In regard to the nature of the nucleic acid, all known plant viruses contain only RNA, while either DNA or RNA may occur in animal and bacterial viruses. The great resemblance in composition—both qualitative and quantitative—between plant and animal viruses of both types suggests a close functional resemblance for the different groups of viruses. Since the isolation of pure TMV, a number of plant viruses have been prepared in pure or near-pure state; several of these were obtained in crystalline or paracrystalline form. A great variety of agents, or conditions—almost all protein denaturants—cause the breakdown of the architecture of the viruses. The method most generally employed for the isolation of native TMV protein makes use of alkali for the degradation of the virus. Several varieties of tobacco give local lesions upon inoculation with TMV and can, thus, be used for quantitative evaluation.