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Infection and Immunity Jun 2019The Gram-negative bacterium is the primary bacterial species associated with bovine respiratory disease (BRD) and is responsible for significant economic losses to...
The Gram-negative bacterium is the primary bacterial species associated with bovine respiratory disease (BRD) and is responsible for significant economic losses to livestock industries worldwide. Healthy cattle are frequently colonized by commensal serotype A2 strains, but disease is usually caused by pathogenic strains of serotype A1. For reasons that are poorly understood, a transition occurs within the respiratory tract and a sudden explosive proliferation of serotype A1 bacteria leads to the onset of pneumonic disease. Very little is known about the interactions of with airway epithelial cells of the respiratory mucosa which might explain the different abilities of serotype A1 and A2 strains to cause disease. In the present study, host-pathogen interactions in the bovine respiratory tract were mimicked using a novel differentiated bovine bronchial epithelial cell (BBEC) infection model. In this model, differentiated BBECs were inoculated with serotype A1 or A2 strains of and the course of infection followed over a 5-day period by microscopic assessment and measurement of key proinflammatory mediators. We have demonstrated that serotype A1, but not A2, invades differentiated BBECs by transcytosis and subsequently undergoes rapid intracellular replication before spreading to adjacent cells and causing extensive cellular damage. Our findings suggest that the explosive proliferation of serotype A1 that occurs within the bovine respiratory tract prior to the onset of pneumonic disease is potentially due to bacterial invasion of, and rapid proliferation within, the mucosal epithelium. The discovery of this previously unrecognized mechanism of pathogenesis is important because it will allow the serotype A1-specific virulence determinants responsible for invasion to be identified and thereby provide opportunities for the development of new strategies for combatting BRD aimed at preventing early colonization and infection of the bovine respiratory tract.
Topics: Animals; Bronchi; Cattle; Epithelial Cells; Mannheimia haemolytica; Pasteurellosis, Pneumonic; Respiratory System; Virulence
PubMed: 30962401
DOI: 10.1128/IAI.00078-19 -
Veterinary Microbiology Apr 2019Bovine respiratory disease (BRD) is economically significant, and influenza D virus (IDV) is commonly identified in cattle with BRD. Mannheimia haemolytica (MHA) is an...
Bovine respiratory disease (BRD) is economically significant, and influenza D virus (IDV) is commonly identified in cattle with BRD. Mannheimia haemolytica (MHA) is an opportunistic bacterial contributor to BRD; surveillance data suggest that MHA and IDV co-infection occurs in cattle. The objective of this study was to evaluate the synergistic pathogenesis in cattle co-infected with IDV and MHA. Sixteen dairy calves were randomly assigned to four groups of four calves. The IDV + MHA + group received D/bovine/C00046 N/Mississippi/2014 (D/46 N) intranasally at 0 days post-inoculation (DPI) and Mannheimia haemolytica D153 (MHA D153) intratracheally at 5 DPI. The IDV + MHA- group received only D/46 N at 0 DPI; the IDV-MHA + group received only MHA D153 at 5 DPI; and the IDV-MHA- group received neither agent. Clinical scores were calculated twice daily. At 10 DPI, IDV + MHA+, IDV-MHA+, and IDV-MHA- calves were euthanized and evaluated for pathologic lesions. The IDV + groups seroconverted to IDV by 10 DPI. Clinical scores were higher in IDV + groups than IDV- groups on 2-5 DPI (p = 0.001). After MHA challenge on 5 DPI, clinical scores (6-10 DPI) were slightly lower in IDV+MHA+ group than IDV-MHA+ group (p < 0.05) but not significantly different between MHA+ groups and MHA- groups. The average gross pathology score was higher for IDV-MHA+ group than groups IDV-MHA- and IDV+MHA+; however, no significant differences were identified among groups. Under the conditions of this study, infection with IDV before MHA enhance neither clinical disease nor lung pathology, relative to calves infected with MHA alone.
Topics: Animals; Cattle; Cattle Diseases; Coinfection; Lung; Male; Mannheimia haemolytica; Orthomyxoviridae Infections; Pasteurellaceae Infections; Respiratory Tract Infections; Seroconversion; Thogotovirus
PubMed: 30955818
DOI: 10.1016/j.vetmic.2019.03.027 -
Veterinary Research Mar 2020Mannheimia haemolytica serotype A2 is the principal cause of pneumonic mannheimiosis in ovine and caprine livestock; this disease is a consequence of immune suppression...
Mannheimia haemolytica serotype A2 is the principal cause of pneumonic mannheimiosis in ovine and caprine livestock; this disease is a consequence of immune suppression caused by stress and associated viruses and is responsible for significant economic losses in farm production worldwide. Gram-negative bacteria such as M. haemolytica produce outer membrane (OM)-derived spherical structures named outer membrane vesicles (OMVs) that contain leukotoxin and other biologically active virulence factors. In the present study, the relationship between M. haemolytica A2 and bovine lactoferrin (BLf) was studied. BLf is an 80 kDa glycoprotein that possesses bacteriostatic and bactericidal properties and is part of the mammalian innate immune system. Apo-BLf (iron-free) showed a bactericidal effect against M. haemolytica A2, with an observed minimal inhibitory concentration (MIC) of 16 µM. Sublethal doses (2-8 µM) of apo-BLf increased the release of OMVs, which were quantified by flow cytometry. Apo-BLf modified the normal structure of the OM and OMVs, as observed through transmission electron microscopy. Apo-BLf also induced lipopolysaccharide (LPS) release from bacteria, disrupting OM permeability and functionality, as measured by silver staining and SDS and polymyxin B cell permeability assays. Western blot results showed that apo-BLf increased the secretion of leukotoxin in M. haemolytica A2 culture supernatants, possibly through its iron-chelating activity. In contrast, holo-BLf (with iron) did not have this effect, possibly due to differences in the tertiary structure between these proteins. In summary, apo-BLf affected the levels of several M. haemolytica virulence factors and could be evaluated for use in animals as an adjuvant in the treatment of ovine mannheimiosis.
Topics: Animals; Anti-Bacterial Agents; Exotoxins; Lactoferrin; Mannheimia haemolytica; Pasteurellosis, Pneumonic; Sheep; Sheep Diseases
PubMed: 32138772
DOI: 10.1186/s13567-020-00759-z -
BMC Microbiology Aug 2020Mannheimia haemolytica strains isolated from North American cattle have been classified into two genotypes (1 and 2). Although members of both genotypes have been... (Comparative Study)
Comparative Study
BACKGROUND
Mannheimia haemolytica strains isolated from North American cattle have been classified into two genotypes (1 and 2). Although members of both genotypes have been isolated from the upper and lower respiratory tracts of cattle with or without bovine respiratory disease (BRD), genotype 2 strains are much more frequently isolated from diseased lungs than genotype 1 strains. The mechanisms behind the increased association of genotype 2 M. haemolytica with BRD are not fully understood. To address that, and to search for interventions against genotype 2 M. haemolytica, complete, closed chromosome assemblies for 35 genotype 1 and 34 genotype 2 strains were generated and compared. Searches were conducted for the pan genome, core genes shared between the genotypes, and for genes specific to either genotype. Additionally, genes encoding outer membrane proteins (OMPs) specific to genotype 2 M. haemolytica were identified, and the diversity of their protein isoforms was characterized with predominantly unassembled, short-read genomic sequences for up to 1075 additional strains.
RESULTS
The pan genome of the 69 sequenced M. haemolytica strains consisted of 3111 genes, of which 1880 comprised a shared core between the genotypes. A core of 112 and 179 genes or gene variants were specific to genotype 1 and 2, respectively. Seven genes encoding predicted OMPs; a peptidase S6, a ligand-gated channel, an autotransporter outer membrane beta-barrel domain-containing protein (AOMB-BD-CP), a porin, and three different trimeric autotransporter adhesins were specific to genotype 2 as their genotype 1 homologs were either pseudogenes, or not detected. The AOMB-BD-CP gene, however, appeared to be truncated across all examined genotype 2 strains and to likely encode dysfunctional protein. Homologous gene sequences from additional M. haemolytica strains confirmed the specificity of the remaining six genotype 2 OMP genes and revealed they encoded low isoform diversity at the population level.
CONCLUSION
Genotype 2 M. haemolytica possess genes encoding conserved OMPs not found intact in more commensally prone genotype 1 strains. Some of the genotype 2 specific genes identified in this study are likely to have important biological roles in the pathogenicity of genotype 2 M. haemolytica, which is the primary bacterial cause of BRD.
Topics: Animals; Bacterial Outer Membrane Proteins; Cattle; Cattle Diseases; Chromosomes, Bacterial; Genotype; Mannheimia haemolytica; Mutation; Phylogeny; Respiratory Tract Infections; Whole Genome Sequencing
PubMed: 32787780
DOI: 10.1186/s12866-020-01932-2 -
Frontiers in Microbiology 2022Bovine Respiratory Disease (BRD) represents a significant burden to the health of feedlot cattle and the profitability of the beef industry in the US. is widely...
Bovine Respiratory Disease (BRD) represents a significant burden to the health of feedlot cattle and the profitability of the beef industry in the US. is widely regarded as the primary bacterial pathogen driving acute BRD. While is most commonly implicated in chronic cases of BRD, this agent's potential role in acute stages of BRD is unclear. Therefore, this study aimed to evaluate potential associations between and during acute BRD in feedlot cattle. Nasal swabs ( = 1,044) were collected over time from feedlot cattle ( = 270) enrolled in an experiment assessing the effect of vaccination for Bovine Respiratory Syncytial Virus (BRSV). Swabs were analyzed for detection of , and BRSV multiplex qPCR assays. Data were analyzed using inverse conditional probability weighted (ICPW) logistic regression models to investigate potential effects of presence on arrival (d0), day seven (d7) and day 14 (d14) post-arrival on prevalence on day 28 (d28) post-arrival, adjusting for the previous history of , BRSV, BRD morbidity, and body weight. The potential association between time-to-BRD detection and presence on d0, d7, and d14 post-arrival, was inferred an ICPW time-to-event model. The presence of in nasal swabs collected on d7 post-arrival was significantly associated with an increase in the prevalence of on d28 (prevalence difference: 45%; 95% Confidence Interval: 31%, 60%; -value < 0.001). Significant time-varying coefficients for presence were detected at d0, d7, and d14 post-arrival in the ICPW time-to-event model (-value < 0.001). The shortest median time-to-BRD detection was 29 days in cattle that were positive on d0, d7, and d14 post-arrival and in those that were positive on d0 and d14 post-arrival. Under the conditions of this study, our findings suggest that may be influencing the respiratory environment during the acute phase of BRD, increasing the abundance of , which could have important impacts on the occurrence of BRD.
PubMed: 35979489
DOI: 10.3389/fmicb.2022.946792 -
Veterinary Medicine and Science Jul 2023Small ruminants are the most numerous of man's domestic livestock. Although sheep represent a great resource for Ethiopia, the net rate of productivity per animal is...
Isolation and identification of Mannheimia haemolytica and Pasteurella multocida from symptomatic and asymptomatic sheep and their antibiotic susceptibility patterns in three selected districts of north Gondar zone, Gondar Ethiopia.
BACKGROUND
Small ruminants are the most numerous of man's domestic livestock. Although sheep represent a great resource for Ethiopia, the net rate of productivity per animal is very low due to many factors including respiratory disorders.
OBJECTIVES
The objectives of this work were to isolate and identify M. haemolytica and P. multocida as well as to assess the antibiotic susceptibility patterns of these isolates. Nasal swab samples were collected aseptically by using 70% alcohol as a disinfectant.
METHODS
A cross-sectional study was conducted in three selected districts of the north Gondar zone, Ethiopia.
RESULTS
From 148 samples collected in 94 (63.5%) asymptomatic and 54 (35.5%) symptomatic sheep, a total of 23 were isolated successfully based on cultural, staining, and biochemical characteristics. Of these isolates, 18 (78.3%) and 5 (21.7%) were M. haeimolytica and P. multocida, respectively. Compared with the total animals examined, the proportion of M. haeimolytica and P. multocida were 12.16 % (n = 18) and 3.38% (n = 5), respectively. All of the isolates were subjected to a panel of 8 antibiotic discs for sensitivity testing. Of the tested antibiotics, chloramphenicol (100%), gentamicin, and tetracycline (82.6%) each and co-trimoxazole (60.8%) were found to be the most effective drugs whereas, both species were completely resistant to vancomycin and showed a very low degree of susceptibility for the rest drugs.
CONCLUSIONS
In conclusion, M. haemolytica was found to be the predominant isolate in all host-related factors and most of the antibiotics were not fully effective against the isolates. Hence, treatment and/or vaccination of ovine pneumonic pasteurellosis should be emphasised to M. haeimolytica using the most effective drugs along with appropriate herd management practices.
Topics: Sheep; Animals; Mannheimia haemolytica; Pasteurella multocida; Ethiopia; Cross-Sectional Studies; Anti-Bacterial Agents
PubMed: 37197762
DOI: 10.1002/vms3.1166 -
Indian Journal of Microbiology Dec 2016Pneumonia caused by is an important disease in ruminants. Because of its economic significance, several methods have been developed to study the pathogenicity and...
Pneumonia caused by is an important disease in ruminants. Because of its economic significance, several methods have been developed to study the pathogenicity and epidemiology of . In this study, bacterial isolates of and identified from the lungs of sheep were serotyped by means of indirect haemagglutination. Of the 598 lungs studied, 34 isolates were identified and serotyped. In decreasing order, serotypes were: not typable (50 %), A1 (17.65 %), A7 (11.76 %), A6 (5.88 %), and A12, A2, A5 and A9 (each representing 2.94 %). The only serotype was T4 (2.94 %). Serotypes A1, A6 and A7 of were the most commonly isolated from pneumonic sheep producing greater changes in the lungs and having important implications for sheep production.
PubMed: 27784951
DOI: 10.1007/s12088-016-0611-7 -
Frontiers in Veterinary Science 2022Bovine respiratory disease (BRD) is considered a major cause of morbidity and mortality in young calves and is caused by a range of infectious agents, including viruses...
Bovine respiratory disease (BRD) is considered a major cause of morbidity and mortality in young calves and is caused by a range of infectious agents, including viruses and bacteria. This study aimed to determine the frequency of viral and bacterial pathogens detected in calves with BRD from high-production dairy cattle herds and to perform the molecular characterization of N and S1 genes in identified bovine coronavirus (BCoV) strains. Nasal swabs were collected from 166 heifer calves, namely, 85 symptomatic and 81 asymptomatic calves aged between 5 and 90 days, from 10 dairy cattle herds. Nasal swabs were evaluated using molecular techniques for the identification of viruses (BCoV, bovine alphaherpesvirus 1, bovine viral diarrhea virus, bovine parainfluenza virus 3, and bovine respiratory syncytial virus) and bacteria (, and ). In addition, five and two BCoV-positive samples were submitted to N and S1 gene amplification and nucleotide sequencing, respectively. The frequency of diagnosis of BCoV was higher (56%, 93/166) than the frequency of (39.8%, 66/166) and (33.1%, 55/166). The three microorganisms were identified in the calves of symptomatic and asymptomatic heifer calve groups. All other pathogens included in the analyses were negative. In the phylogenetic analysis of the S1 gene, the Brazilian strains formed a new branch, suggesting a new genotype, called # 15; from the N gene, the strains identified here belonged to cluster II. This study describes high rates of BCoV, , and in heifer calves from high-production dairy cattle herds with BRD. Additionally, the molecular characterization provides evidence that the circulating BCoV strains are ancestrally different from the prototype vaccine strains and even different BCoV strains previously described in Brazil.
PubMed: 35692294
DOI: 10.3389/fvets.2022.895492 -
Frontiers in Veterinary Science 2022The threat of bovine respiratory disease (BRD) for cattle operations is exacerbated by increasing prevalence of antimicrobial resistance (AMR) in , a leading cause of...
The threat of bovine respiratory disease (BRD) for cattle operations is exacerbated by increasing prevalence of antimicrobial resistance (AMR) in , a leading cause of BRD. Characterization of AMR in by culture and susceptibility testing is complicated by uncertainty regarding the number of colonies that must be selected to accurately characterize AMR phenotypes (antibiograms) and genotypes in a culture. The study objective was to assess phenotypic and genotypic diversity of isolates on nasopharyngeal swabs (NPS) from 28 cattle at risk for BRD or with BRD. NPS were swabbed onto five consecutive blood agar plates; after incubation up to 20 colonies were selected per plate (up to 100 colonies per NPS). Phenotype was determined by measuring minimum inhibitory concentrations (MIC) for 11 antimicrobials and classifying isolates as resistant or not. Genotype was indirectly determined by matrix-assisted laser desorption/ionization time of flight mass spectroscopy (MALDI-TOF MS). NPS from 11 of 28 cattle yielded at least one isolate; median (range) of isolates per NPS was 48 (1-94). NPS from seven cattle yielded one phenotype, 3 NPS yielded two, and 1 NPS yielded three; however, within a sample all phenotypic differences were due to only one MIC dilution. On each NPS all isolated were the same genotype; genotype 1 was isolated from three NPS and genotype two was isolated from eight. Diversity of on bovine NPS was limited, suggesting that selection of few colonies might adequately identify relevant phenotypes and genotypes.
PubMed: 35647109
DOI: 10.3389/fvets.2022.883389 -
Genome Feb 2022Common bacterial causes of bovine respiratory disease (BRD) include , , and . Within , two major genotypes are commonly found in cattle (1 and 2); however, genotype 2...
Common bacterial causes of bovine respiratory disease (BRD) include , , and . Within , two major genotypes are commonly found in cattle (1 and 2); however, genotype 2 strains are isolated from diseased lungs much more frequently than genotype 1 strains. Outer membrane proteins (OMPs) of , , and genotype 2 may be important factors for acquired host immunity. The predicted OMP differences between genotypes 1 and 2 have been previously identified. In this study, we expanded the focus to include bovine-isolated strain genomes representing all three species and the two genotypes. Reported here are the core genomes unique to each of them, core genomes shared between some or all combinations of the three species and two genotypes, and predicted OMPs within these core genomes. The OMPs identified in this study are potential candidates for further studies and the development of interventions against BRD.
Topics: Animals; Bacterial Outer Membrane Proteins; Cattle; Genotype; Mannheimia haemolytica; Pasteurella multocida
PubMed: 34348051
DOI: 10.1139/gen-2021-0038