Mice and sows were taken as the subpot in this experiment. The stains with pill and enerotoxins gcducible of the Escherichia coli were cultivated respeDtively. Then, the cultured cell suspensions were mixed and treated with forrnalin for inactivation. The vaccine was prcduced with aluminum hydroxide gel or Freund complete adjuvant. The result obtained in the immunizing experiment indicated that the vaccine of aluminum hydroxide gel group had been absorbed better, and no induration or tumefaction phenomenon had been observed. On the other hand, the complete adjuvant vaccine group had side effects. There was still abscess or granulation tissre remaining in the vaccinated region till the test was completed.
As to the cabillty of immunization in mice with the vaccine, koth Al-gel group and the complete adjuvant group were resistant to the challenge. Their survival rate was between )- 1(0%. For the sows immunized in the labc’ratory, the tiers of the anti- labile enerotoxin and anti-k88 pill antibedies were higher in the complete adjuvant vaccine group. But the titer of anti-k99 and 987p pill were higher in the Al-gel Vaccine group. the suckling piglets had a similar condition to that of their mothers. ununarY
The result obtained in the field applicatin test with aluminum hydroxide gel vaccine group indicated that the anti-pill titer in sea of the pregnant sows significantly increased after immunization, The tier in sea of their suckling piglet was alsohigh. The antibcxly of heat labile enerotoxins in sows was undeetable before lmccination. But the antibcdy titer after immunization on farm A or B indicated an increase in amount between 2-32 times, while the mcde was 4 times. Among 22 sows on farm A 8 had the tier in the serum specimen up to ?32 times. Passive antibdy of piglet on farm A had antibcdy of heat labile enterotoxins up to?32 times (13.6%).
In terms of the clinical protective effect, among the 710 piglet of immunization groug diarrhea of 76 piglet (10,7%) was observd, while thatof 163 piglets (37%) among the control group of 441 piglet was rerorded, As regards the final mortality, there were 12 piglet dead (1.7%) in the experimental group. In the control groug 112 piglet died (25.4%), This proves that an excellent protDtive effect can be obtained, which kee piglet from cohIzillcsis if this vaccine is used to immunize the pregnant sows.