Intestinal mucosal protection against F4+ ETEC in pigs by oral immunisation with purified F4 fimbriae

摘要

Enterotoxigenie Escherichia coli (ETEC) are an important cause of diarrhoea and mortality in neonatal and recently weaned piglets. Some of these ETEC strains bear F4 fimbriae, by which they adhere to specific receptors (F4R), present on brush borders of villous enlerocytes, and consequently colonise the small intestine. Neonatal infections can be prevented effectively by passive colostral and lactogenic immunity which can be obtained and increased by vaccination of the sow. After weaning however, the piglets become susceptible again to ETEC infections. At that moment, the induction of an active mucosal immune response is required to evoke a protective immunity. It has recently been demonstrated that oral F4 administration in pigs induces a mucosalimmune response. In the present study it is shown that F4R are a prerequisite for an immune response following oral immunisation. Furthermore, indications were obtained that oral F4 immunisation can induce mucosal protection. Fifteen F4 seronegative piglets (6-week-old) were used. All animals were killed at the end of the experiment to determine the presence of F4R on their villous enterocytes.