Correlation Between Hemagglutinating Antibody and Mouse Protection in Antipasteurella (Pasteurella Multocida) Sera

Rabbits were immunized against types B and E Pasteurella multocida. The protective capacities of the sera were determined by mouse protection tests. The HA titers of these sera were determined by a standardized indirect hemagglutination test. A linear relation was observed when the protective values of the immune sera (log of the number of LD 50's against which the mean of the ED 50's (4.25 × 10 −2 ml) protects 50% of mice) were plotted against the logs of the HA titers of the same sera.