[The use of the toxin binding inhibition test for potency testing of Clostridium novyi type B alpha toxoid vaccines]. / Anwendung des Toxin-Bindungs-Inhibitionstests zur Wirksamkeitsprüfung von Clostridium-novyi-Typ-B-Alphatoxoid-Impfstoffen.

The toxin binding inhibition test (ToBI) were developed for potency testing of C. novyi type B alpha toxoid containing veterinary vaccines to replace the currently used toxin neutralisation test in mice (TNT). The antitoxin titres of rabbit sera (AN-, HV- and SP sera) were determined with ToBI using the international reference serum with known antitoxin titre. In order to show the validity of the methods, the results were compared with those of the manufacturers/regulatory authorities and correlation coefficients were calculated. The correlation coefficients were r = 0.93 (AN sera), r = 0.73 (HV sera) and r = 0.85 (SP sera). All correlations were statistically significant. The specificity of the methods could be proved using heterologous antisera. The results of the ToBI were reproducible. Thus, the ToBI offers a suitable in vitro method for the determination of the antitoxin titre of rabbit antisera as an alternative to the toxin neutralisation in mice for potency testing of vaccines containing C. novyi type B alpha toxoid.

Course of infection and humoral immune reaction in calves infected orally with different Salmonella serovars.

5 groups of five calves each were orally infected with the salmonella serovar S. agona, S. dublin, S. enteritidis, S. infantis or S. typhimurium. The course of infection and the humoral immune response against 5 antigen preparations of the homologous and the 4 heterologous salmonella serovars were monitored in each group. Antibodies against two different protein antigens and against two differently prepared LPS antigens were determined by ELISA and the level of H-agglutinin was assessed by micro agglutination test. All 5 serovars proved to be virulent for calves. The specificity of antibodies produced following the infection are not always consistent with the Kauffmann-White scheme. There was a relation of age and strain for infection on immune response, whereas the severity of infection did no correlate with an increase of antibody production. The serological tests used were good for investigation of a defined host-parasite-interaction but not satisfactory for serovar specific diagnosis of salmonella infection in cattle.