[An oral enteritis-vaccine composed of twelve heat inactivated Enterobacteriaceae. 2. Communication: the immunogenicity after treatment with simulated gastric and intestinal juice proved in an active mouse protection test (author's transl)].

In the first communication (3), we reported on the conception, the composition, and the efficacy of the polyvalent oral vaccine from 6 strains of salmonellae, 2 strains of shigellae, and 4 strains of dyspepsia coli. The inactivation took place at 100 degrees C/3 min. The question going to be answered in this communication was as follows: Does the immunogenicity of the vaccine decreased during the gastrointestinal passage under influence of acid and enzymes? We allowed the vaccine to react with simulated gastric juice and/or pepsin at pH = 3 and 37 C/60 min on the one hand and with simulated intestinal juice and/or pancreatin at pH = 7 and 37 degrees C/180 min on the other hand either individually or in combination. The vaccinal preparations produced this way were examined for their immunogenicity in the mouse protection test. The mice were orally immunized with the aid of a probang for ten times (total dose = 3.75 x 10(10) germs) and intraperitoneally infected with the virulent enteropathogenic strain of E. coli 2,380 being contained in the twelvefold vaccine on the 10. day after the last oral vaccination. In the main test, 70.4% of 351 non-vaccinated control animals died. 277 mice were immunized with the vaccine having been treated in the strongest way (gastric juice + pepsin + intestinal juice + pancreatin); 4.0% of those died which is an index of efficacy of 94.3. The mice immunized with untreated vaccine served as positive controls and were protected in the same way; 3.1% of 255 mice died (index of efficacy = 95.6). The results show that the simulated gastro-intestinal passage did not have a negative influence upon the immunogenicity of the polyvalent vaccine.