[Trials to obtain conjugates for the passive hemagglutination test with chromium chloride and their use in studying foot-and-mouth disease viruses].

Experiments were carried out to produce conjugates for the hemagglutination-inhibition reaction with the aid of chromic chloride. Studies with reference F.M.D. viruses and with CFT revealed that the antibody erythrocyte diagnostic agents were highly specific, and were stable in storage at +4 degrees C and in freeze-drying. It was found that the conjugates obtained with F.M.D. antigens possessed high specificity, however, were not stable and 7 to 10 days later lost their activity. Tests with the hemagglutination-reaction showed that immunity itself could be studied in cattle treated with F.M.D. vaccines. A correlation was found between the results obtained via the hemagglutination reaction and those obtained with the aid of the virus-neutralization test.