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E. coli O157:H7 is a foodborne pathogen responsible for bloody diarrhea, hemorrhagic colitis and hemolytic uremic syndrome (HUS). The objective of the present work was to evaluate the ability of colostral IgG obtained from Stx2-immunized cows to prevent against E. coli O157:H7 infection and Stx2 cytotoxicity. Hyperimmune colostrum (HC) was obtained from cows intramuscularly immunized with inactivated Stx2 or vehicle for controls. Colostral IgG was purified by affinity chromatography. Specific IgG antibodies against Stx2 and bovine lactoferrin (bLF) levels in HC and the corresponding IgG (HC-IgG/bLF) were determined by ELISA. The protective effects of HC-IgG/bLF against Stx2 cytotoxicity and adhesion of E. coli O157:H7 and its Stx2-negative mutant were analyzed in HCT-8 cells. HC-IgG/bLF prevention against E. coli O157:H7 was studied in human colon and rat colon loops. Protection against a lethal dose of E. coli O157:H7 was evaluated in a weaned mice model. HC-IgG/bLF showed high anti-Stx2 titers and high bLF levels that were able to neutralize the cytotoxic effects of Stx2 in vitro and in vivo. Furthermore, HC-IgG/bLF avoided the inhibition of water absorption induced by E. coli O157:H7 in human colon and also the pathogenicity of E. coli O157:H7 and E. coli O157:H7Δstx2 in rat colon loops. Finally, HC-IgG/bLF prevented in a 100% the lethality caused by E. coli O157:H7 in a weaned mice model. Our study suggests that HC-IgG/bLF have protective effects against E. coli O157:H7 infection. These beneficial effects may be due to specific anti-Stx2 neutralizing antibodies in combination with high bLF levels. These results allow us to consider HC-IgG/bLF as a nutraceutical tool which could be used in combination with balanced supportive diets to prevent HUS. However further studies are required before recommendations can be made for therapeutic and clinical applications., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is responsible for intestinal disease and hemolytic uremic syndrome (HUS), a serious systemic complication which particularly affects children. In this study, we evaluated whether passive immunization protects from EHEC O157:H7 colonization and renal damage, by using a weaned BALB/c mouse model of infection. Recombinant proteins EspB and the carboxyl-terminal fragment of 280 amino acids of γ-intimin (γ-IntC280) were used in combination with a macrophage-activating lipopeptide-2 (MALP) adjuvant to immunize pregnant mice by the intranasal route. Neonatal mice were allowed to suckle vaccinated or sham-vaccinated dams until weaning when they were challenged by the oral route with a suspension of an E. coli O157:H7 Stx2+ strain. The excretion of the inoculated strain was followed for 72h. All vaccinated dams exhibited elevated serum IgG response against both γ-Int C280 and EspB. Passive immunization of newborn mice resulted in a significant increase in serum IgG titers against γ-Int C280 and a slight increase in EspB-specific antibodies. The neonates from vaccinated dams showed a significant reduction in EHEC O157:H7 colonization 48h post challenge. In addition, the level of plasma urea concentration, a marker of renal failure, was significantly higher in offsprings of sham-vaccinated mice. In conclusion, vaccination of pregnant dams with γ-Int C280 and EspB could reduce colonization and systemic toxicity of EHEC O157:H7 in their suckling offsprings., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Escherichia coli O157:H7 is responsible for severe intestinal disease and hemolytic uremic syndrome (HUS), a serious systemic complication which particularly affects children. Cattle are the primary reservoir for E. coli O157:H7 and the main source of infection for humans. In this study, we evaluated the ability of transferred maternal colostral antibodies against γ-Intimin C280 and EspB, to protect young weaned calves from E. coli O157:H7 infection. Hyperimmune colostra were obtained by immunization of pregnant cows with a mix of the mentioned antigens. All vaccinated cows mounted a significant IgG response against γ-Intimin C280, and EspB in sera and colostra. Colostrum-fed calves also exhibited high serum IgG titers against γ-Intimin C280 and EspB along with a rise in mucosal γ-Intimin C280-specific IgG antibodies at recto-anal junction and ileum. Additionally, 70 day-old calves received a challenge with E. coli O157:H7 but no reduction in total bacterial shedding or frequency of E. coli O157:H7 excretion from these calves was observed. Most tissue samples showed granulocyte focal infiltrations of the lamina propria and enterocyte erosion. In conclusion, up to the 70th day, the passively acquired γ-Intimin-C280 and EspB-IgG antibodies present in sera and recto-anal mucosa reached a titer insufficient to reduce EHEC O157 shedding and damages of experimentally inoculated young calves., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Enterohaemorrhagic Escherichia coli (EHEC) O157:H7 is the most prevalent EHEC serotype that has been recovered from patients with haemolytic uremic syndrome (HUS) worldwide. Vaccination of cattle, the main reservoir of EHEC O157:H7, could be a logical strategy to fight infection in humans. This study evaluated a vaccine based on the carboxyl-terminal fragment of 280 amino acids of γ-intimin (γ-intimin C₂₈₀) and EspB, two key colonization factors of E. coli O157:H7. Intramuscular immunization elicited significantly high levels of serum IgG antibodies against both proteins. Antigen-specific IgA and IgG were also induced in saliva, but only the IgA response was significant. Following experimental challenge with E. coli O157:H7, a significant reduction in bacterial shedding was observed in vaccinated calves, compared to control group. These promising results suggest that systemic immunization of cattle with intimin and EspB could be a feasible strategy to reduce EHEC O157:H7 faecal shedding in cattle., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Mucosal vaccine formulations based on purified recombinant C280 gamma-Intimin and EspB (Escherichia coli secreted protein B) from enterohaemorragic E. coli co-administered with a pegylated derivative of the TLR2/6 agonist MALP-2 (macrophage-activating lipopeptide) as adjuvant were evaluated in BALB/c mice. After intranasal vaccination, strong humoral and cellular immune responses were observed against C280 gamma-Intimin and EspB. Sera of immunized mice inhibit bacterial haemolytic activity in vitro. Antigen-specific T-cell proliferation, IL-4, IL-2 and IFN-gamma producing cells, and secretory IgA were mostly detected in animals receiving MALP-2 as adjuvant. These results suggest that C280 gamma-Intimin and EspB are good candidate antigens to be incorporated into mucosal vaccines against this important pathogen.