engleski

Elicitation of intestinal immunity by enterotoxigenic and nonenterotoxigenic strains of Escherichia coli in weaned pigs

We are presenting evidences for local (intestinal) stimulation of cellular and humoral immune responses by F4ac^+ nonenterotoxigenic E. coli (non-ETEC) strain 2407 in 4-week-old pigs perorally challenged with F4ac^+ ETEC strain 11-800/1/94. Additionally, we have evaluated adjuvanticity of copolymer of polyoxyethylene-polyoxypropylene (POE-POP) and N-acetylglucosaminyl-(beta 1-4)-N-acetyl-muraminyl-L-alanyl-D-isoglutamine (GMDP) in a model of postweaning colibacillosis. Small intestinal washes were obtained immediately after euthanasia at 8, 10 and 12 days following the specific immunization, and the presence of anti-F4ac secretory IgA (sIgA) antibody was detected by use of an indirect ELISA. Simultaneously, the specimens from jejunum, ileum, and mesenteric lymph node (MLN) were taken for immunohistology staining of immune cells using monoclonal antibodies reactive with swine leukocyte CD antigens. About 75% of 2407+POE-POP-treated pigs, and 50% to 60% of pigs that were immunized with either 2407+GMDP or 2407 strain, respectively, had anti-F4ac sIgA antibodies. A specific sIgA was also found in 75% of nonimmunized, but challenged pigs. In 2407+GMDP- or 2407-treated pigs we have observed that T cell antigen - CD3a - was expressed on jejunal/ileal intraepithelial lymphocytes and numerous cells in the extrafollicular areas of MLN and dome region of ileal Peyer’s patches (IPP). The B cells expressing CD21 surface molecule were demonstrable in the interfollicular areas of MLN and the germinal centers of IPP in 2407-treated pigs. A strong reaction to sIgA was exhibited by plasma cells in the lumen of the crypts and by those residing the lamina propria of jejunum/ileum. It is proposed that peroral immunization of weaned pigs with F4ac^+ non-ETEC strain may elicit the protective immunity against the challenge infection with ETEC strain expressing a same type of fimbrial antigen.

E.coli; weaned pigs; intestinal immunity; sIgA; immune response modifiers; immunohistochemical staining

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