Читать книгу Principles of Virology - Jane Flint, S. Jane Flint - Страница 95

The specificity of the antibody-antigen reaction has been used to design a variety of assays for viral proteins and antiviral antibodies. These techniques, such as immunostaining, immunoprecipitation, immunoblotting, and the enzyme-linked immunosorbent assay, are by no means limited to virology: all these approaches have been used extensively to study the structures and functions of cellular proteins.

Virus neutralization. When a virus preparation is inoculated into an animal, an array of antibodies is produced. These antibodies can bind to virus particles, but not all of them can block infectivity (neutralize), as discussed in Volume II, Chapter 4. Virus neutralization assays are usually conducted by mixing dilutions of antibodies with virus, incubating them, and assaying for remaining infectivity in cultured cells, eggs, or animals. The end point is defined as the highest dilution of antibody that inhibits the development of cytopathic effect in cells or virus reproduction in eggs or animals.

Some neutralizing antibodies define type-specific antigens on the virus particle. For example, the three serotypes of poliovirus are distinguished on the basis of neutralization tests: type 1 poliovirus is neutralized by antibodies to type 1 virus but not by antibodies to type 2 or type 3 poliovirus. The results of neutralization tests were once used for virus classification, a process now accomplished largely by comparing viral genome sequences. Nevertheless, the detection of antiviral antibodies in animal sera is still extremely important for identifying infected hosts. These antibodies may also be used to map the three-dimensional structure of neutralization antigenic sites on the virus particle (Box 2.7).