Intranasal Bacterial Therapeutics Reduce Colonization by the Respiratory Pathogen Mannheimia haemolytica in Dairy Calves

ABSTRACT Six Lactobacillus strains originating from the nasopharyngeal microbiota of cattle were previously characterized in vitro and identified as candidate bacterial therapeutics (BTs) for mitigating the bovine respiratory pathogen Mannheimia haemolytica. In the present study, these BT strains were evaluated for their potential to (i) reduce nasal colonization by M. haemolytica, (ii) modulate the nasal microbiota, and (iii) stimulate an immune response in calves experimentally challenged with M. haemolytica. Twenty-four Holstein bull calves (1 to 3 weeks old) received either an intranasal BT cocktail containing 6 Lactobacillus strains (3 × 109 CFU per strain; BT + Mh group) 24 h prior to intranasal M. haemolytica challenge (3 × 108 CFU) or no BTs prior to challenge (Mh, control group). Nasal swab, blood, and transtracheal aspiration samples were collected over the course of 16 days after BT inoculation. Counts of M. haemolytica were determined by culturing, and the nasal and tracheal microbiotas were evaluated using 16S rRNA gene sequencing. Serum cytokines (interleukin-6 [IL-6], IL-8, and IL-10) were quantified by enzyme-linked immunosorbent assay (ELISA). Administration of BT reduced nasal colonization by M. haemolytica (P = 0.02), modified the composition and diversity of the nasal microbiota, and altered interbacterial relationships among the 10 most relatively abundant genera. The BT + Mh calves also had a lower relative abundance of Mannheimia in the trachea (P < 0.01) but similar cytokine levels as Mh calves. This study demonstrated that intranasal BTs developed from the bovine nasopharyngeal Lactobacillus spp. were effective in reducing nasal colonization by M. haemolytica in dairy calves. IMPORTANCE Bovine respiratory disease (BRD) is one of the significant challenges for the modern dairy industry in North America, accounting for 23 to 47% of the total mortality among pre- and postweaned dairy heifers. Mass medication with antibiotics is a common practice to control BRD in dairy cattle. However, the emergence of multidrug-resistant BRD pathogens highlights the importance of developing alternatives to antibiotics for BRD mitigation. Using a targeted approach, we recently identified 6 Lactobacillus strains originating from the bovine respiratory microbiota as candidates to be used as bacterial therapeutics (BTs) for the mitigation of the BRD pathogen Mannheimia haemolytica. Here, we demonstrated that intranasal inoculation of the BT strains reduced nasal colonization by M. haemolytica in dairy calves experimentally challenged with this pathogen. This study, for the first time, shows the potential use of intranasal BTs as an alternative to mitigate BRD pathogens in cattle.

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Proteomic Analysis and Immunogenicity of Mannheimia haemolytica Vesicles

Clinical and Vaccine Immunology ◽

10.1128/cvi.00622-12 ◽

2012 ◽

Vol 20 (2) ◽

pp. 191-196 ◽

Cited By ~ 17

Author(s):

Sahlu Ayalew ◽

Anthony W. Confer ◽

Binu Shrestha ◽

Amanda E. Wilson ◽

Marie Montelongo

Keyword(s):

Outer Membrane Proteins ◽

Mannheimia Haemolytica ◽

Dairy Calves ◽

Enzyme Linked Immunosorbent Assay ◽

Content Type ◽

Whole Cells ◽

Liquid Chromatography Tandem Mass ◽

Circulating Antibodies ◽

Membrane Components ◽

Antibody Levels

ABSTRACTMannheimia haemolytica, a major causative agent in bovine respiratory disease, inflicts extensive losses each year on cattle producers. Commercially available vaccines are only partially efficacious. Immunity toM. haemolyticarequires antibodies to secreted toxins and outer membrane proteins (OMPs) of the bacterium. Gram-negative bacteria produce membrane blebs or vesicles, the membrane components of which are primarily derived from OMPs. Accordingly, vesicles have been used as immunogens with various degrees of success. This study characterized components ofM. haemolyticavesicles and determined their immunogenicity in mice and cattle. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis of vesicles from this bacterium identified 226 proteins, of which 58 (25.6%) were OMPs and periplasmic and one (0.44%) was extracellular. Vesicles were used to vaccinate dairy calves and BALB/c mice. Analyses of sera from calves and mice by enzyme-linked immunosorbent assay (ELISA) showed that circulating antibodies againstM. haemolyticawhole cells and leukotoxin were significantly higher on days 21 and 28 (P< 0.05) than on day 0. For control calves and mice, there were no significant differences in serum anti-whole-cell and leukotoxin antibody levels from days 0 and 21 or 28, respectively. Lesion scores of lungs from vaccinated calves (15.95%) were significantly (P< 0.05) lower than those from nonvaccinated calves (42.65%). Sera from mice on day 28 and calves on day 21 showed 100% serum bactericidal activity. Sera from vesicle-vaccinated mice neutralized leukotoxin.

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Changes in Bacterial Diversity Associated with Epithelial Tissue in the Beef Cow Rumen during the Transition to a High-Grain Diet

Applied and Environmental Microbiology ◽

10.1128/aem.00375-11 ◽

2011 ◽

Vol 77 (16) ◽

pp. 5770-5781 ◽

Cited By ~ 56

Author(s):

Yanhong Chen ◽

Gregory B. Penner ◽

Meiju Li ◽

Masahito Oba ◽

Le Luo Guan

Keyword(s):

Bacterial Diversity ◽

Denaturing Gradient Gel Electrophoresis ◽

Pcr Analysis ◽

Control Group ◽

Epithelial Tissue ◽

Rrna Gene ◽

Content Type ◽

Beef Cow ◽

Dietary Transition ◽

Gradient Gel Electrophoresis

ABSTRACTOur understanding of the ruminal epithelial tissue-associated bacterial (defined as epimural bacteria in this study) community is limited. In this study, we aimed to determine whether diet influences the diversity of the epimural bacterial community in the bovine rumen. Twenty-four beef heifers were randomly assigned to either a rapid grain adaptation (RGA) treatment (n= 18) in which the heifers were allowed to adapt from a diet containing 97% hay to a diet containing 8% hay over 29 days or to the control group (n= 6), which was fed 97% hay. Rumen papillae were collected when the heifers were fed 97%, 25%, and 8% hay diets. PCR-denaturing gradient gel electrophoresis (DGGE) and quantitative real-time PCR analysis were used to characterize rumen epimural bacterial diversity and to estimate the total epimural bacterial population (copy numbers of the 16S rRNA gene). The epimural bacterial diversity from RGA heifers changed (P= 0.01) in response to the rapid dietary transition, whereas it was not affected in control heifers. A total of 88 PCR-DGGE bands were detected, and 44 were identified from phyla includingFirmicutes,Bacteroidetes, andProteobacteria. The bacteriaTreponemasp.,Ruminobactersp., andLachnospiraceaesp. were detected only when heifers were fed 25% and 8% hay diets, suggesting the presence of these bacteria is the result of adaptation to the high-grain diets. In addition, the total estimated population of rumen epimural bacteria was positively correlated with molar proportions of acetate, isobutyrate, and isovalerate, suggesting that they may play a role in volatile fatty acid metabolism in the rumen.

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Evaluation of Cross Protective Efficacy of Commercial Vaccines against Mannheimia haemolytica in Mice

The Iraqi Journal of Veterinary Medicine ◽

10.30539/iraqijvm.v43i1.487 ◽

2019 ◽

Vol 43 (1) ◽

pp. 165-170

Author(s):

Waffa A. Ahmed

Keyword(s):

Immunosorbent Assay ◽

Protective Efficacy ◽

Challenge Test ◽

Cross Protection ◽

Mannheimia Haemolytica ◽

Economic Losses ◽

Enzyme Linked Immunosorbent Assay ◽

Control Group ◽

Significant Difference ◽

Protection Efficacy

Mannheimia haemolytica together with Pasteurella multocida represents as a major bacterial causative agent of cattle, sheep and goats respiratory diseases and its one of the most important causes for economic losses to these animals .Commercially available vaccines were used to prevent infections caused by P. multocida and M. haemolytica. Thus, the aim of the present study was to evaluate the cross protection efficacy of two vaccines to protect mice against M.haemolytica, studying humeral immunity, using Enzyme-Linked Immunosorbent Assay. Forty five mice were divided into three equal groups, group one and two were inoculated subcutaneously 4μl\JOVAPAST® and 1μl of Al-kindy vaccines respectively, while the third group was with 0.5 ml sub cutaneous PBS. LD50for M.haemolytica was estimated as 2× 106 cfu \ml and challenge test was conducted by dropping 0.05 ml 2× 106 cfu \ml intranasally after three weeks of immunization for the three groups. The results of Enzyme-Linked Immunosorbent Assay, showed significant increase of antibody titters at (P<0.01) in (group 1 and 2) after first and second weeks post immunization, in comparison with control group. Also, the re-isolation of M.haemolytica from lungs tissue of all groups after challenged were positive with significant difference between control and immunized group, control group was 4× 108 cfu ∕ml which was higher than immunized group one and group two,which were 2.5×104 cfu∕ml and 3,5×105 cfu∕ml respectively after 24 hour of vaccine. In conclusion, the two commercial vaccines showed good cross protection efficacy against M. haemolytica, but JOVAPAST® vaccine showed higher efficacy than Alkindy vaccine, as that it contain two heterologous killed strains and providing the basis for production a vaccine from the two pathogen of local strains.

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Development of Bacterial Therapeutics against the Bovine Respiratory Pathogen Mannheimia haemolytica

Applied and Environmental Microbiology ◽

10.1128/aem.01359-19 ◽

2019 ◽

Vol 85 (21) ◽

Cited By ~ 6

Author(s):

Samat Amat ◽

Edouard Timsit ◽

Danica Baines ◽

Jay Yanke ◽

Trevor W. Alexander

Keyword(s):

Respiratory Disease ◽

Animal Health ◽

Bovine Respiratory Disease ◽

Feedlot Cattle ◽

Mitigation Strategies ◽

Commensal Bacteria ◽

Mannheimia Haemolytica ◽

Respiratory Pathogen ◽

Content Type

ABSTRACT Bovine respiratory disease (BRD) is a major cause of morbidity and mortality in beef cattle. Recent evidence suggests that commensal bacteria of the bovine nasopharynx have an important role in maintaining respiratory health by providing colonization resistance against pathogens. The objective of this study was to screen and select bacterial therapeutic candidates from the nasopharynxes of feedlot cattle to mitigate the BRD pathogen Mannheimia haemolytica. In a stepwise approach, bacteria (n = 300) isolated from the nasopharynxes of 100 healthy feedlot cattle were identified and initially screened (n = 178 isolates from 12 different genera) for growth inhibition of M. haemolytica. Subsequently, selected isolates were evaluated for the ability to adhere to bovine turbinate (BT) cells (n = 47), compete against M. haemolytica for BT cell adherence (n = 15), and modulate gene expression in BT cells (n = 10). Lactobacillus strains had the strongest inhibition of M. haemolytica, with 88% of the isolates (n =33) having inhibition zones ranging from 17 to 23 mm. Adherence to BT cells ranged from 3.4 to 8.0 log10 CFU per 105 BT cells. All the isolates tested in competition assays reduced M. haemolytica adherence to BT cells (32% to 78%). Among 84 bovine genes evaluated, selected isolates upregulated expression of interleukin 8 (IL-8) and IL-6 (P < 0.05). After ranking isolates for greatest inhibition, adhesion, competition, and immunomodulation properties, 6 Lactobacillus strains from 4 different species were selected as the best candidates for further development as intranasal bacterial therapeutics to mitigate M. haemolytica infection in feedlot cattle. IMPORTANCE Bovine respiratory disease (BRD) is a significant animal health issue impacting the beef industry. Current BRD prevention strategies rely mainly on metaphylactic use of antimicrobials when cattle enter feedlots. However, a recent increase in BRD-associated bacterial pathogens that are resistant to metaphylactic antimicrobials highlights a pressing need for the development of novel mitigation strategies. Based upon previous research showing the importance of respiratory commensal bacteria in protecting against bronchopneumonia, this study aimed to develop bacterial therapeutics that could be used to mitigate the BRD pathogen Mannheimia haemolytica. Bacteria isolated from the respiratory tracts of healthy cattle were characterized for their inhibitory, adhesive, and immunomodulatory properties. In total, 6 strains were identified as having the best properties for use as intranasal therapeutics to inhibit M. haemolytica. If successful in vivo, these strains offer an alternative to metaphylactic antimicrobial use in feedlot cattle for mitigating BRD.

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Effect of Dietary Supplementation with a Saccharomyces cerevisiae Mannan Oligosaccharide on the Bacterial Community Structure of Broiler Cecal Contents

Applied and Environmental Microbiology ◽

10.1128/aem.05028-11 ◽

2011 ◽

Vol 77 (18) ◽

pp. 6653-6662 ◽

Cited By ~ 31

Author(s):

A. Corrigan ◽

K. Horgan ◽

N. Clipson ◽

R. A. Murphy

Keyword(s):

Community Structure ◽

Bacterial Community ◽

16S Rrna ◽

16S Rrna Gene ◽

Bacterial Community Structure ◽

Dietary Supplementation ◽

Control Group ◽

Rrna Gene ◽

Content Type ◽

Mannan Oligosaccharide

ABSTRACTThis study investigated the effects of dietary supplementation with a prebiotic mannan oligosaccharide (MOS) on broiler performance, bacterial community structure, and phylogenetic populations of cecal contents. Bird performance data were collected, and cecal samples were extracted from randomly caught poults from each treatment group every 7 days from hatching to the age of 42 days. Weight gain, feed consumption, and feed efficiency ratios did not differ significantly between groups. Automated ribosomal intergenic spacer analysis (ARISA) of the bacterial communities in birds receiving MOS-supplemented diets indicated that dietary supplementation with MOS at either of 2 levels significantly altered the bacterial community structure from that of the control group on all sample days. The phylogenetic identities of bacteria contained within the cecum were determined by constructing a 16S rRNA gene clone library. A total of 594 partial 16S rRNA gene sequences from the cecal contents were analyzed and compared for the three dietary treatments. The dominant bacteria of the cecum belonged to three phyla,Firmicutes,Bacteroidetes, andProteobacteria; of these,Firmicuteswere the most dominant in all treatment groups. Statistical analysis of the bacterial 16S rRNA gene clone libraries showed that the compositions of the clone libraries from broilers receiving MOS-supplemented diets were, in most cases, significantly different from that of the control group. It can be concluded that in this trial MOS supplementation significantly altered the cecal bacterial community structure.

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Antibodies against Mycobacterial Proteins as Biomarkers for HIV-Associated Smear-Negative Tuberculosis

Clinical and Vaccine Immunology ◽

10.1128/cvi.00805-13 ◽

2014 ◽

Vol 21 (6) ◽

pp. 791-798 ◽

Cited By ~ 7

Author(s):

Michael Siev ◽

Douglas Wilson ◽

Supreet Kainth ◽

Victoria O. Kasprowicz ◽

Catherine M. Feintuch ◽

...

Keyword(s):

South African ◽

Serum Antibody ◽

Positive Tuberculin Skin Test ◽

Antibody Detection ◽

Enzyme Linked Immunosorbent Assay ◽

Control Group ◽

Sputum Smear ◽

Content Type ◽

Positive Antibody ◽

Smear Negative

ABSTRACTSerology data are limited for patients with sputum smear-negative HIV-associated active tuberculosis (TB). We evaluated the serum antibody responses against the mycobacterial proteins MPT51, MS, and echA1 and the 38-kDa protein via enzyme-linked immunosorbent assay (ELISA) in South African (S.A.) HIV-positive (HIV+) smear-negative TB patients (n= 56), U.S. HIV+controls with a positive tuberculin skin test (TST+;n= 21), and S.A. HIV-negative (HIV−) (n= 18) and HIV+(n= 24) controls. TB patients had positive antibody reactivity against MPT51 (73%), echA1 (59%), MS (36%), and the 38-kDa protein (11%). Little reactivity against MPT51 and echA1 was observed in control groups at low risk for TB, i.e., S.A. HIV−(0% and 6%, respectively), and at moderate risk for TB development, i.e., U.S. HIV+TST+controls (14% and 10%, respectively). By contrast, more reactivity was detected in the S.A. HIV+control group at higher risk for TB (25% and 45%, respectively). Our data hold promise that antibody detection against MPT51 and echA1 might have adjunctive value in the detection of HIV+smear-negative TB and might reflect increasingMycobacterium tuberculosisinfection activity in asymptomatic HIV+individuals.

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Mannheimia haemolytica and Its Leukotoxin Cause Macrophage Extracellular Trap Formation by Bovine Macrophages

Infection and Immunity ◽

10.1128/iai.06120-11 ◽

2012 ◽

Vol 80 (5) ◽

pp. 1923-1933 ◽

Cited By ~ 56

Author(s):

Nicole A. Aulik ◽

Katrina M. Hellenbrand ◽

Charles J. Czuprynski

Keyword(s):

Mannheimia Haemolytica ◽

Respiratory Pathogen ◽

Blood Monocytes ◽

Macrophage Cell ◽

Peripheral Blood Monocytes ◽

Content Type ◽

Extracellular Traps ◽

Extracellular Trap ◽

Bovine Neutrophils ◽

Mouse Macrophage Cell Line

ABSTRACTHuman and bovine neutrophils release neutrophil extracellular traps (NETs), which are protein-studded DNA matrices capable of extracellular trapping and killing of pathogens. Recently, we reported that bovine neutrophils release NETs in response to the important respiratory pathogenMannheimia haemolyticaand its leukotoxin (LKT). Here, we demonstrate macrophage extracellular trap (MET) formation by bovine monocyte-derived macrophages exposed toM. haemolyticaor its LKT. Both native fully active LKT and noncytolytic pro-LKT (produced by anlktCmutant ofM. haemolytica) stimulated MET formation. Confocal and scanning electron microscopy revealed a network of DNA fibrils with colocalized histones in extracellular traps released from bovine macrophages. Formation of METs required NADPH oxidase activity, as previously demonstrated for NET formation. METs formed in response to LKT trapped and killed a portion of theM. haemolyticacells. Bovine alveolar macrophages, but not peripheral blood monocytes, also formed METs in response toM. haemolyticacells. MET formation was not restricted to bovine macrophages. We also observed MET formation by the mouse macrophage cell line RAW 264.7 and by human THP-1 cell-derived macrophages, in response toEscherichia colihemolysin. The latter is a member of the repeats-in-toxin (RTX) toxin family related to theM. haemolyticaleukotoxin. This study demonstrates that macrophages, like neutrophils, can form extracellular traps in response to bacterial pathogens and their exotoxins.

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Substrate Binding Protein SBP2 of a Putative ABC Transporter as a Novel Vaccine Antigen of Moraxella catarrhalis

Infection and Immunity ◽

10.1128/iai.01832-14 ◽

2014 ◽

Vol 82 (8) ◽

pp. 3503-3512 ◽

Cited By ~ 13

Author(s):

Taketo Otsuka ◽

Charmaine Kirkham ◽

Antoinette Johnson ◽

Megan M. Jones ◽

Timothy F. Murphy

Keyword(s):

Otitis Media ◽

Moraxella Catarrhalis ◽

Binding Protein ◽

Substrate Binding ◽

Vaccine Antigen ◽

Enzyme Linked Immunosorbent Assay ◽

Control Group ◽

Chronic Obstructive ◽

Content Type ◽

Substrate Binding Protein

ABSTRACTMoraxella catarrhalisis a common respiratory tract pathogen that causes otitis media in children and infections in adults with chronic obstructive pulmonary disease. Since the introduction of the pneumococcal conjugate vaccines with/without protein D of nontypeableHaemophilus influenzae,M. catarrhalishas become a high-priority pathogen in otitis media. For the development of antibacterial vaccines and therapies, substrate binding proteins of ATP-binding cassette transporters are important targets. In this study, we identified and characterized a substrate binding protein, SBP2, ofM. catarrhalis. Among 30 clinical isolates tested, thesbp2gene sequence was highly conserved. In 2 different analyses (whole-cell enzyme-linked immunosorbent assay and flow cytometry), polyclonal antibodies raised to recombinant SBP2 demonstrated that SBP2 expresses epitopes on the bacterial surface of the wild type but not thesbp2mutant. Mice immunized with recombinant SBP2 showed significantly enhanced clearance ofM. catarrhalisfrom the lung compared to that in the control group at both 25-μg and 50-μg doses (P< 0.001). We conclude that SBP2 is a novel, attractive candidate as a vaccine antigen againstM. catarrhalis.

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Identification of the Immunogenic Outer Membrane Protein A Antigen of Haemophilus parasuis by a Proteomics Approach and Passive Immunization with Monoclonal Antibodies in Mice

Clinical and Vaccine Immunology ◽

10.1128/cvi.05223-11 ◽

2011 ◽

Vol 18 (10) ◽

pp. 1695-1701 ◽

Cited By ~ 15

Author(s):

Huabin Tian ◽

Fang Fu ◽

Xuesong Li ◽

Xin Chen ◽

Wei Wang ◽

...

Keyword(s):

Monoclonal Antibodies ◽

Field Isolate ◽

Protein A ◽

Passive Immunization ◽

Enzyme Linked Immunosorbent Assay ◽

Control Group ◽

Bacterial Cells ◽

Haemophilus Parasuis ◽

Two Dimensional Gel Electrophoresis ◽

Content Type

ABSTRACTMonoclonal antibodies (MAbs) againstHaemophilus parasuiswere generated by fusing spleen cells from BALB/c mice immunized with whole bacterial cells with SP2/0 murine myeloma cells. Desirable hybridomas were screened by enzyme-linked immunosorbent assay (ELISA). Neutralizing MAb 1D8 was selected in protection assays. ELISA results demonstrated that 1D8 can react with all 15 serotypes ofH. parasuisand field isolateH. parasuisHLJ-018. Passive immunization studies showed that mice inoculated intraperitoneally with 1D8 had significantly reduced prevalence ofH. parasuiscolonization in the blood, lung, spleen, and liver and had prolonged survival time compared to that of the control group. Furthermore, the passive transfer experiment indicated that MAb 1D8 can protect mice from both homologous and heterologous challenges withH. parasuis. Using two-dimensional gel electrophoresis (2-DE), the immunoreactive protein target for MAb 1D8 was identified. The data presented confirm the protective role of MAb 1D8 and identify OmpA as the target of the protective monoclonal antibody. The data suggest that OmpA is a promising candidate for a subunit vaccine againstH. parasuis.

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Repeated Oral Vaccination of Cattle with Shiga Toxin-Negative Escherichia coli O157:H7 Reduces Carriage of Wild-Type E. coli O157:H7 after Challenge

Applied and Environmental Microbiology ◽

10.1128/aem.02183-20 ◽

2020 ◽

Vol 87 (2) ◽

Author(s):

Smriti Shringi ◽

Haiqing Sheng ◽

Andrew A. Potter ◽

Scott A. Minnich ◽

Carolyn J. Hovde ◽

...

Keyword(s):

Escherichia Coli ◽

Human Disease ◽

Vaccine Group ◽

Enzyme Linked Immunosorbent Assay ◽

Control Group ◽

Human Pathogen ◽

Wild Type ◽

Content Type ◽

E Coli ◽

Challenge Control

ABSTRACT Subcutaneous vaccination of cattle for enterohemorrhagic Escherichia coli O157:H7 reduces the magnitude and duration of fecal shedding, but the often-required, repeated cattle restraint can increase costs, deterring adoption by producers. In contrast, live oral vaccines may be repeatedly administered in feed, without animal restraint. We investigated whether oral immunization with live stx-negative LEE+ E. coli O157:H7 reduced rectoanal junction (RAJ) colonization by wild-type (WT) E. coli O157:H7 strains after challenge. Two groups of cattle were orally dosed twice weekly for 6 weeks with 3 × 109 CFU of a pool of three stx-negative LEE+ E. coli O157:H7 strains (vaccine group) or three stx-negative LEE− non-O157:H7 E. coli strains (control group). Three weeks following the final oral dose, animals in both groups were orally challenged with a cocktail of four stx+ LEE+ E. coli O157:H7 WT strains. Subsequently, WT strains at the RAJ were enumerated weekly for 4 weeks. Serum antibodies against type III secretion protein (TTSP), the translocated intimin receptor (Tir), and EspA were determined by enzyme-linked immunosorbent assay (ELISA) at day 0 (preimmunization), day 61 (postimmunization, prechallenge), and day 89 (postchallenge). Vaccine group cattle had lower numbers of WT strains at the RAJ than control group cattle on postchallenge days 3 and 7 (P ≤ 0.05). Also, vaccine group cattle shed WT strains for a shorter duration than control group cattle. All cattle seroconverted to TTSP, Tir, and EspA, either following immunization (vaccine group) or following challenge (control group). Increased antibody titers against Tir and TTSP postimmunization were associated with decreased numbers of WT E. coli O157:H7 organisms at the RAJ. IMPORTANCE The bacterium E. coli O157:H7 causes foodborne disease in humans that can lead to bloody diarrhea, kidney failure, vascular damage, and death. Healthy cattle are the main source of this human pathogen. Reducing E. coli O157:H7 in cattle will reduce human disease. Using a randomized comparison, a bovine vaccine to reduce carriage of the human pathogen was tested. A detoxified E. coli O157:H7 strain, missing genes that cause disease, was fed to cattle as an oral vaccine to reduce carriage of pathogenic E. coli O157:H7. After vaccination, the cattle were challenged with disease-causing E. coli O157:H7. The vaccinated cattle had decreased E. coli O157:H7 during the first 7 days postchallenge and shed the bacteria for a shorter duration than the nonvaccinated control cattle. The results support optimization of the approach to cattle vaccination that would reduce human disease.

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