ABSTRACT. The protection conferred by egg antibody specific for F18-fimbriae against infection with F18 + Escherichia coli was studied in controlled passive immunization trials involving weaned pigs. Parameters of protection consisted of body weight gain, frequency and severity of diarrhea and recovery of the challenge strain of F18 + E. coli. Weaned pigs at four weeks of age were challenge exposed once daily for three days by oral inoculation with 10 11 cfu of virulent F18 + E. coli followed by daily administration of antibody supplemented feed for 9 days starting from the first challenge day 0. Results showed a dose-dependent response to antibody treatment. The group of pigs given 1:50 titer of antibody in feed had less frequency of diarrhea (P<0.01-0.05), higher rate of gain (P<0.01) and lower isolation rate of challenge strain in rectal and intestinal swabs (P<0.01) compared to non-treated control. In the same manner, the anti-F18 antibody significantly reduced adherence of F18 + E. coli to pig intestinal epithelial cells in vitro (P<0.01). Results suggest that egg antibodies specific for the F18 fimbriae is a suitable immunotherapeutic agent for pigs infected with F18 + E. coli and that pigs can be protected from overt clinical disease and the subsequent reduced performance arising from infection with this pathogen. -KEY WORDS : egg antibody, Escherichia coli, F18 fimbriae, passive immunity, porcine postweaning diarrhea.J. Vet. Med. Sci. 59(10): 917-921, 1997 passive immunity with anti-fimbrial antibodies essentially prevents bacterial adherence by interfering with the surface localized fimbriae from adhering to intestinal receptors. The net effect is reduced extent and intensity of colonization precluding the overt expression of clinical disease. Recently, we have shown that the use of orally administered egg antibodies directed against the K88, K99, and 987P fimbriae of E. coli effectively prevented diarrhea in neonatal isolated pigs [12]. In this report, we extend this study by using egg antibodies directed against the F18 fimbriae involving weaned pigs. MATERIALS AND METHODSBacteria and cultivation conditions: E. coli strain 8199 (O141ab: H4: F18ac + : STIa, STII) [9] was obtained from Prof. Bertschinger, Institute of Veterinary Bacteriology, University of Zürich, Switzerland. The bacteria were grown on Iso-Sensitest Agar (Oxoid, Unipath Ltd., Hampshire, England) containing the dye Alizarin yellow R (Sigma, MO, U.S.A.), 0.0625% w/v for 20 hr at 37°C in an atmosphere containing 5% CO 2 [11]. The bacteria were suspended in phosphate-buffered saline (PBS; pH 7.2), the fimbriae detached by incubating the suspension in a water bath at 60°C for 20 min with shaking (50 rpm), and the bacterial cells removed by centrifugation for 20 min at 12,000 × g, 4°C. The fimbriae were precipitated by adding 20% v/v of saturated ammonium sulfate followed by centrifugation for 20 min at 12,000 × g. The pellet was resuspended in 0.1 M Tris-HCl buffer (pH 8.8) and dialyzed against the same buffer. The suspension was applied...
Three types of Bifidobacterium thermophilum extract were prepared and fed to 2-wk-old chickens to evaluate their usefulness in enhancing the defense activity of the chickens against pathogenic Escherichia coli. All three preparations resulted in significant reduction (P < 0.05) of E. coli numbers in the lungs of the treated chicken groups compared with the control nontreated group. Besides, improvement in the survival rate was observed in the treated chicken groups, especially the one administered the enzyme-digested B. thermophilum extract sample. Concanavalin A-stimulated lymphocytes from the latter group demonstrated significantly higher proliferation activity compared with those from the control group. These results suggest that oral administration of B. thermophilum preparations may be used to enhance the resistance of chickens against E. coli infection.
A simple, reproducible and high yield method of Helicobacter pylori urease enzyme purification was developed using a heparinoid (Cellufine sulfate) affinity gel. The purification method involved two sequential steps using the same gel that takes advantage of the differential affinity of urease to the heparinoid at two levels of hydrogen ion concentration. SDS-polyacrylamide gel electrophoresis analysis of affinity-purified urease revealed two major protein bands with about 62-and 30-kDa molecular mass. When whole cell lysates of clinical and laboratory strains of H. pylori were probed by Western blot, anti-urease hyperimmune serum produced by affinity-purified urease in rabbit recognized only the two bands corresponding to the urease A and B subunits. To probe the molecular relevance of affinity gel adherence to mucin adherence, the purified urease was derivatized with N-hydroxysuccinimidobiotin and used in adherence assays. Competitive inhibition tests revealed commonality of urease receptors among gastric mucin, heparin, and heparinoid. Composite data on adherence kinetics modulated by pH, salt, incubation time, and concentration of urease or mucin were indicative of conformation-dependent ligand-receptor interaction.
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