Reduced faecal shedding of Escherichia coli O157:H7 in cattle following systemic vaccination with γ-intimin C₂₈₀ and EspB proteins.

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.

Vilte DA ，Larzábal M ，Garbaccio S ，Gammella M ，Rabinovitz BC ，Elizondo AM ，Cantet RJ ，Delgado F ，Meikle V ，Cataldi A ，Mercado EC ... -  《-》

Physiopathological effects of Escherichia coli O157:H7 inoculation in weaned calves fed with colostrum containing antibodies to EspB and Intimin.

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.

Rabinovitz BC ，Vilte DA ，Larzábal M ，Abdala A ，Galarza R ，Zotta E ，Ibarra C ，Mercado EC ，Cataldi A ... -  《-》

Efficacy of a recombinant Intimin, EspB and Shiga toxin 2B vaccine in calves experimentally challenged with Escherichia coli O157:H7.

Escherichia coli O157:H7 is a zoonotic pathogen of global importance and the serotype of Shiga toxin-producing E.coli (STEC) most frequently associated with Hemolytic Uremic Syndrome (HUS) in humans. The main STEC reservoir is cattle. Vaccination of calves with the carboxy-terminal fraction of Intimin γ (IntC280) and EspB can reduce E.coli O157:H7 fecal shedding after experimental challenge. Shiga toxin (Stx) exerts local immunosuppressive effects in the bovine intestine and Stx2B fused to Brucella lumazine synthase (BLS-Stx2B) induces Stx2-neutralizing antibodies. To determine if an immune response against Stx could improve a vaccine's effect on fecal shedding, groups of calves were immunized with EspB + IntC280, with EspB + IntC280 + BLS-Stx2B, or kept as controls. At 24 days post vaccination calves were challenged with E.coli O157:H7. Shedding of E.coli O157:H7 was assessed in recto-anal mucosal swabs by direct plating and enrichment followed by immunomagnetic separation and multiplex PCR. Calves were euthanized 15 days after the challenge and intestinal segments were obtained to assess mucosal antibodies. Vaccination induced a significant increase of IntC280 and EspB specific antibodies in serum and intestinal mucosa in both vaccinated groups. Antibodies against Stx2B were detected in serum and intestinal mucosa of animals vaccinated with 3 antigens. Sera and intestinal homogenates were able to neutralize Stx2 verocytotoxicity compared to the control and the 2-antigens vaccinated group. Both vaccines reduced E.coli O157:H7 shedding compared to the control group. The addition of Stx2B to the vaccine formulation did not result in a superior level of protection compared to the one conferred by IntC280 and EspB alone. It remains to be determined if the inclusion of Stx2B in the vaccine alters E.coli O157:H7 shedding patterns in the long term and after recurrent low dose exposure as occurring in cattle herds.

Martorelli L ，Garimano N ，Fiorentino GA ，Vilte DA ，Garbaccio SG ，Barth SA ，Menge C ，Ibarra C ，Palermo MS ，Cataldi A ... -  《-》

Vaccination of pregnant cows with EspA, EspB, γ-intimin, and Shiga toxin 2 proteins from Escherichia coli O157:H7 induces high levels of specific colostral antibodies that are transferred to newborn calves.

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a major cause of intestinal disease and hemolytic uremic syndrome, a serious systemic complication that particularly affects children. Cattle are primary reservoirs for EHEC O157:H7 and the main source of infection for humans. Vaccination of cattle with different combinations of bacterial virulence factors has shown efficacy in decreasing EHEC O157:H7 shedding. It is, therefore, important to demonstrate whether vaccination of pregnant cows with EHEC O157:H7 induces high titers of transferable antibodies to avoid early colonization of calves by the bacteria. In this study we evaluated the ability of EspA, EspB, the C-terminal fragment of 280 amino acids of γ-intimin (γ-intimin C₂₈₀) and inactivated Shiga toxin (Stx) 2 proteins to induce specific antibodies in colostrum and their passive transference to colostrum-fed calves. Friesian pregnant cows immunized by the intramuscular route mounted significantly high serum and colostrum IgG responses against EspB and γ-intimin C₂₈₀ that were efficiently transferred to their calves. Antibodies to EspB and γ-intimin C₂₈₀ were detected in milk samples of vaccinated cows at d 40 postparturition. Significant Stx2-neutralizing titers were also observed in colostrum from Stx2-vaccinated cows and sera from colostrum-fed calves. The results presented showed that bovine colostrum with increased levels of antibodies against EHEC O157:H7 may be obtained by systemic immunization of pregnant cows, and that these specific antibodies are efficiently transferred to newborn calves by feeding colostrum. Hyperimmune colostrum and milk may be an alternative to protect calves from early colonization by EHEC O157:H7 and a possible key source of antibodies to block colonization and toxic activity of this bacterium.

Rabinovitz BC ，Gerhardt E ，Tironi Farinati C ，Abdala A ，Galarza R ，Vilte DA ，Ibarra C ，Cataldi A ，Mercado EC ... -  《-》

Immunization of sheep with a combination of intiminγ, EspA and EspB decreases Escherichia coli O157:H7 shedding.

Enterohaemorrhagic Escherichia coli O157:H7 are zoonotic pathogens associated with haemorrhagic colitis (HC) and the haemolytic uremic syndrome (HUS). Ruminants are the main reservoir of this organism and most outbreaks of E. coli O157:H7 infections are food borne. Food contamination by ruminant manure has been reported as the primary source of human infection, therefore inhibition of E. coli O157:H7 colonization and shedding in ruminants could control the risk of human exposure to this pathogen. In the present study a vaccine based on the translocon proteins EspA and EspB and the outer membrane adhesion factor intiminγ significantly reduced faecal shedding of E. coli O157:H7 by orally infected sheep. Protection correlates with serum antibody responses to the defined antigens and validates the targeting of these colonization factors. Whereas vaccination has been described in cattle, this is the first study describing a significant decrease in faecal shedding following systemic immunization of sheep.

Yekta MA ，Goddeeris BM ，Vanrompay D ，Cox E ... -  《-》