Determination of the Vi-antigen content of acetone-dried typhoid vaccines

Summary

A number of typhoid strains and coli strain 5396/38 are compared for their Vi-antigen content with the aid of complement fixation and erythrocyte sensibilization tests. Acetone-killed and dried germs were used as source material. Parallel batches derived from the same strain showed good agreement. Moreover, results with erythrocyte sensibilization and complement fixation reaction were closely correlated. The conclusion is drawn that serological determination of the Vi-antigen of acetone-dried typhoid vaccine is possible. Further investigations, however, must be carried out to compare the functional capacity to produce antibodies of strains with the same serologically determined content of Vi-antigen.