Preparation of antigens

This chapter describes the procedures of purification, concentration, and preservation of antigens. The most general concept to begin with is the most important—the microbiological purity of the starting viral culture. For every virus antigen, there should be a parallel normal antigen to serve as the negative control in the test. Normal antigens are prepared by shaminoculating cell cultures with negative culture material and following these cultures through the entire virus culture and antigen preparation steps in exact parallel fashion. Depending on the test and the day-to-day usage, many antigens are preserved by adding thimerosal to the final product to a final concentration of 1:10,000, or sodium azide to a final concentration of 0.1%. Special preparation of antigens is required for many diagnostic tests, monoclonal or polyclonal antibody production, and many enzyme immunoassays tests. Many viruses and antigens have their own peculiarities based on the specific properties of each virus group. Chromatography is considered to be the most effective means of producing purified preparations of virus proteins, this being achieved by gel filtration, ion exchange, or affinity chromatography.