Abstract
In the field of virus study, the electron microscope technique of negative staining is now more than 10 years old, and during these years the knowledge of virus fine structure has changed beyond all recognition. This chapter describes that the immune aggregate should be incubated for 1 hour at 37°C and then left in the cold overnight. This is the optimum approach for a system, where the concentration of neither the antigen nor the antiserum is known, and maximum clumping is needed. However, with many systems these parameters have been established, and if it is known that clumping can be obtained readily, for example, as with the avian infectious bronchitis system, then incubation for 1 hour at 37°C is sufficient, followed by spinning at 10,000 rpm for half an hour. Viruses in the small to intermediate size range are ideal for immune studies, as the particles are not disproportionately larger than the antibody molecules attached to them, and interaction between them can be visualized with better than 10 a resolution. Particles as large as the poxviruses are becoming too large for good resolution of antibody molecules to be obtained, and aggregates of poxvirus particles are usually too dense to be recorded photographically except at low power. In the field of clinical virology, there is a possibility that the electron microscope technique of negative staining will become a standard method of diagnosis. As far as research is concerned, the present article seems to have described the beginnings that have been made in the visualization of several aspects of antigen-antibody interaction. Each line investigated has yielded a few answers, but of much greater importance, has led to a better understanding of what questions should be asked. At present, viral antigens can only occasionally be obtained in pure form, such that there are only a very few systems where controlled and specific virus-antigen-antibody systems can be visualized.
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