Production of recombinant vaccine of K99 fimbrial adhesion from toxigenic E. coli.

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Enterotoxigenic E. coil with K99 fimbrial antigen causes diarrhea in newborn calves, piglets and lambs. The fimbriae consist of 8 subunits ; a major subunit called fimbrillin forms fimbrial structure and a minor subunit celled adhesion locates at the tip of fimbriae. Adhesoin recognizes carbohydrate epitope on the surface of host intestinal mucosa. In this project, adhesoin gene was identified, and host receptor glycosphingolipid structure and postnatal change in content were determined.1)Among 8 fimbrial genes(fana to fanh), DNA sequences of fanE and fanF which were still unknown were analyzed. The sequence of fanf had E. coli, therefore, fanf product seems to be adhesoin. However, fanF product did not show adhesoin activity. Both fanf and fane products were necessary for showing the activity.homology to those of other adhesoin genes from different kinds of2)Ganglioside GM3(NeuGc) : NeuGcalpha2-3Galbeta1-4Glc-Cer was a major glycosphingolipid component in intestinal mucosa from newborn calves and piglets. This ganglioside was bound by ^<125>I-labelled bacteria. The most potent affinity for the binding was detected in a major component of the ganglioside with 2-hydoxyl C16 fatty acid and phytosphingosine. The high affinity component dramatically decleased in the content after birth ; 50% at 1-week age, 30% at 2-week age and only 2y. at adult age. The decrease of the receptor molecule can explain the age registance of the E. coli infection.