[The choice of optimal sensitizing dose of the antigen in the preparation of cholera erythrocytic diagnostic agent, with consideration to the avidity of antibodies under study].

The authors studied the comparative antigenic activity in the indirect hemagglutination test (IHAT) of erythrocytic diagnostic agents sensitized with various doses of cholera O-antigen. A definite dependence of the IHAT results on the avidity degree of the antibodies determined in the serum was demonstrated. To ascertain the maximal levels of highly avid antibodies (in the hyperimmune cholera sera) it is possible to use antigen doses exceeding the optimal sensitizing ones. In examination of less avid antibodies (for example in the blood sera of cholera patients) the diagnostic agent in such doses displayed decreased IHAT titres. To increase the reliability of the IHAT results it is recommended to choose the sensitizing antigen doses for the preparation of the diagnostic agent to be used in the IHAT with consideration to the avidity of antibodies examined in the blood sera.