Immunoenzymatic determination (ELISA) of the white clover mosaic virus and alfalfa mosaic virus in clover and leguminous crops

The application of immunoglobulin (IgG), isolated from rabit antiserums, against the Czechoslovak isolates of white clover mosaic virus (WCMV, the TrM1 isolate) and alfalfa mosaic virus (AMV, the TrM6A isolate) were verified for the ELISA method. In the used antiserums, the antibody titer, determined by the precipitation reaction, was 1:640 - 1:1280 and in the IgG fraction it was 1:80 (anti-AMV IgG) or 1:160 (anti-WCMV IgG). In the anti-WCMV IgG, the antibodies of specific types were present in the concentration twice as high as in the anti-AMV IgG. There was optimum concentration of antibodies for the ELISA procedure in the anti-AMV IgG diluted 1:1000 and in the anti-WCMV IgG diluted 1:2000. The reaction intensity of the less diluted IgG that reacted with the homologous antigene was not proportional to the antibodies concentration in the tested IgG samples. Direct proportional dependence of reaction intensity on the antigene concentration in the analysed samples of purified WCMV and AMV was only within the range of the optimum concentration of antigene that enabled its quantitative determination. Reaction intensity of the WCMV and AMV suspensions gradually diluted more than 1:8000, was proportional to the grade of antigene dilution in the tested samples of purified virus suspensions. Less diluted WCMV and AMV suspensions (e. g. 1:1000 - 1:8OOO) also specifically reacted with the homologous IgG, but the intensity of reaction was not proportional to the antigene concentration in the tested samples of virus suspensions. The reaction intensity in reactions with the extracts of healthy plants, or of plants infected with the heterologous WCMV anti-AMV IgG did not overcome the absorbance 0.25. In the extracts of spontaneously infected plants the WCMV and AMV antigene was detected by the ELISA method with the same sensitivity and reliability as by the test with indicator plants.