Chapter I - The Problems of Virology

Abstract

Publisher Summary Virus research is a segment of experimental biology and inevitably encounters the same methodological and interpretative difficulties that beset every phase of fundamental biology. There are various chemical and physical techniques for the purification or isolation of molecules, macromolecules, and larger aggregates for obtaining smaller or larger quantities of pure virus. For most viruses, the ultracentrifuge is probably the most important tool for purification. Where small viruses must be separated from particular fractions of host cells of similar size and density, purification may require the use of all the empirical artifices. The progress of purification is normally followed by assessing the biological activity in relation to the amount of material in the fraction. Where viruses have biological activity other than their power to infect and cause demonstrable lesions, this is convenient to use in combined chemical–biological work. Influenza viruses act as hemagglutinins, and many types of virus can be detected and titrated by complement fixation tests with appropriate antisera. With purified material, it is possible to use a variety of physical methods to define size, shape, and density of the infective units and to elaborate in regard to electrostatic charge, electron density of different regions, and adsorption to various types of surface.