Comparative structural and immunological analysis of outer membrane proteins and dermonecrotic toxin in Bordetella bronchiseptica canine isolate.

Bordetella bronchiseptica is a pathogen causing respiratory infections in mammals. With the improving understanding of companion animals' welfare, addressing the side effects of bordetella vaccine gains importance in dogs. Studies on diverse subunit vaccines are actively pursued in humans to safely and effectively control bordetellosis. Therefore, our objective was to develop a canine bordetella vaccine inspired by human vaccine development. We evaluated the immunogenicity of the two bacterial components: the outer membrane proteins (OMPs) and the dermonecrotic toxin (DNT) from a canine isolate of B. bronchiseptica. In-silico analysis identified eight domains of DNT, and Domain 3 was selected as the most promising antigen candidate. Additionally, the OMPs were extracted and examined using SDS-PAGE and Western blot analysis. The distinct immunological characteristic of OMPs and DNT-3 were examined individually and in combination. Gene expression and cytokine production were also evaluated in DH82 cells after stimulation with those antigens. Treatment with OMPs resulted in higher level of Th1 related cytokines, while DNT-3 induced a predominant response associated with Th17 and Th2 in the cytokine production. Synergistic effects were observed exclusively on IL-23, indicating increase of a potential risk of side effects when OMPs and DNT act together. These findings provide valuable insights into the reactogenicity of conventional Bordetella vaccines. Further, the presented preclinical data in this study offer an alternative method of the development for an optimal next-generation Bordetella vaccine for companion animals and humans, replacing the acellular vaccines containing both toxin and protein components.

Effect of carbohydrates on the adhesion of Bordetella bronchiseptica to the respiratory epithelium in rabbits.

This study proposes an ecological approach for preventing respiratory tract infections caused by Bordetella bronchiseptica in mammals using a mixture of carbohydrates. In an in vivo study, 51-day-old New Zealand rabbits were treated with a solution containing 1 × 107 CFUs of B. bronchiseptica and 250 µg of one of the following carbohydrates: N acetylglucosamine (GlcNAc), N acetylgalactosamine (GalNAc), alpha methyl mannose (AmeMan), alpha methyl glucose (AmeGlc) and sialic acid (Neu5AC). Positive (B. bronchiseptica) and negative (Physiological Saline Solution (PSS)) controls were included. Animals treated with GlcNAc or AmeGlc showed no clinical signs of infection and exhibited a significant reduction (p < 0.05) in the severity of microscopic lesions evaluated in the nasal cavity and lung compared with the positive controls. Additionally, the presence of bacteria was not detected through microbiological isolation or PCR in the lungs of animals treated with these sugars. Use of a mixture of GlcNAc and AmeGlc resulted in greater inhibition of microscopic lesions, with a significant reduction (p < 0.05) in the severity of these lesions compared to the results obtained using individual sugars. Furthermore, the bacterium was not detected through microbiological isolation, Polymerase Chain Reaction (PCR) or indirect immunoperoxidase (IIP) in this group.

Prior infection with Bordetella bronchiseptica enhanced colonization but not disease with Streptococcus suis.

Bordetella bronchiseptica and Streptococcus suis are widely distributed swine pathogens. B. bronchiseptica is a primary pathogen and causes atrophic rhinitis and bronchopneumonia. S. suis is a contributing agent to porcine respiratory disease complex and causes systemic diseases including arthritis, meningitis, polyserositis, and septicemia. Colonization with B. bronchiseptica has been associated with increased colonization by other pathogenic bacteria and increased disease severity with viral and bacterial pathogens. It has also been reported to predispose cesarean derived, colostrum deprived (CDCD) piglets to S. suis systemic disease. Here, we evaluated the role of B. bronchiseptica colonization on S. suis colonization, dissemination, and disease in one study using conventional pigs and another using CDCD pigs. Pigs were challenged with S. suis, B. bronchiseptica, or B. bronchiseptica followed by S. suis. Incidence of S. suis disease was not increased in either study for animals pre-inoculated with B. bronchiseptica. Nasal colonization with S. suis was increased in coinfected animals, while B. bronchiseptica was similar between mono- and co-infected animals. Although increased S. suis disease was not seen in coinfected pigs, there is evidence that B. bronchiseptica can increase colonization with S. suis, which may contribute to enhanced disease when animals are stressed or immunocompromised.

Outbreak management of multidrug-resistant Bordetella bronchiseptica in 16 shelter-housed cats.

CASE SERIES SUMMARY: This case series describes an outbreak of multidrug-resistant (MDR) Bordetella bronchiseptica in 16 shelter-housed cats with infectious respiratory disease. Four cats presented with acute dyspnea on the same day, each with a history of previous upper respiratory disease that had resolved with treatment. Early diagnostic testing and culture and sensitivity allowed for targeted antimicrobial therapy and environmental interventions. A case definition based on exposure and clinical signs identified 12 additional presumptive cases, including the likely index case. Comprehensive outbreak management included diagnostic testing, risk assessment, vaccination, use of isolation and quarantine, increased surveillance and review of biosecurity practices. The outbreak resolved in 26 days. RELEVANCE AND NOVEL INFORMATION: Management of an MDR B bronchiseptica outbreak in shelter-housed cats has not been previously described. Along with standard population and environmental measures, early and appropriate use of necropsy, PCR and bacterial culture allowed rapid and appropriate use of effective, second-line antibiotics. Shelters are resource-challenged population centers. Veterinarians working in animal shelters can play an important role in helping to develop cost-efficient and effective antimicrobial stewardship practices for companion animal settings. Outbreak management expertise and funding for diagnostic testing, as well as application of the principles of antimicrobial stewardship, are essential components of shelter medicine practice.

Pathogenicity of Bordetella bronchiseptica isolated from apparently healthy rabbits in guinea pig, rat, and mouse.

Bordetella bronchiseptica (B. bronchiseptica) is associated with respiratory tract infections in laboratory animals. In our laboratory animal facility, B. bronchiseptica was isolated from 21 of 27 apparently healthy rabbits obtained from a breeding farm contaminated with B. bronchiseptica. Restriction fragment length polymorphism (RFLP) analysis showed that the flagellin genotype of isolates from the laboratory animal facility and breeding farm was type A, which is seen relatively frequently in rabbits in Europe. To examine its pathogenicity, guinea pigs, rats, and mice were inoculated intranasally with a representative strain isolated in the laboratory animal facility. Following inoculation of 107 colony forming unit (cfu), severe inflammation was observed in the lungs of guinea pig and mice, although the inflammation was less severe in rats. The strain was recovered from the trachea and lungs of these species after inoculation with lower dose such as 103 or 104 cfu. These results suggest that the isolated strain causes respiratory tract infection in guinea pigs, rats, and mice, and that its pathogenicity higher in mice than in rats. This study extends our knowledge of interpreting the microbiologic status of laboratory animals, which will contribute to the development of reliable and reproducible animal experiments.

Oral vaccination of dogs with a monovalent live-avirulent vaccine confers 1 year of immunity against Bordetella bronchiseptica challenge.

This experimental challenge study assessed immune protection 1 year after a single dose of live-attenuated oral Bordetella bronchiseptica (Bb) vaccine in dogs. Forty Bb-seronegative 7-9-week-old puppies were randomly assigned at Day 0 to receive a single oral dose of either Bb vaccine (n = 20; vaccinated group) or sterile water (n = 20; control group). Groups were housed separately until comingling 1 day pre-challenge (Day 365). Challenge with virulent aerosolized Bb occurred at Day 366. Clinical scores were obtained at Days 1-7, and 366-380. Bb microagglutination test (MAT) titers were obtained at Days -7, 0, monthly post-vaccination, and Days 358, 365, and 380. Nasal swabs were collected for microbiological assessment at Days -7, 0, 365, and 367-380. Oral Bb vaccination was not associated with side effects. Pre-challenge, vaccinated dogs developed persistent Bb MAT titers and control dogs remained seronegative. Post-challenge, duration of cough was longer in control dogs (least square means [LSM], 8.6 days) than vaccinated dogs (LSM, 1.5 days; P < 0.0001), with more control dogs having cough on 2 or more consecutive days (control group, n = 17/19, 89.5%; vaccinated group, n = 3/19, 15.8%; P = 0.0011). Post-challenge, Bb shedding occurred in all control dogs and 5/19 (26%) vaccinated dogs. Average duration of Bb shedding was longer in the control group (11.9 days vs. 0.6 days; P < 0.0001) and nasal Bb loads were higher in the control group (P < 0.00001). Orally administered Bb vaccine stimulated immunity that was still protective against virulent Bb challenge after 1 year.

Comparison of C-reactive protein concentrations in dogs with Bordetella bronchiseptica infection and aspiration bronchopneumonia.

BACKGROUND: C-reactive protein (CRP) is a well-known acute-phase protein in dogs that may discriminate bacterial bronchopneumonia from other pulmonary conditions. Bronchopneumonia caused by Bordetella bronchiseptica (Bb) is common but the associated increase in CRP concentration in naturally infected dogs has not been fully explored. OBJECTIVE: To compare CRP concentrations of dogs with Bb infection, with or without radiographic pulmonary lesions, to dogs with aspiration bronchopneumonia (ABP). ANIMALS: Sixteen dogs with Bb infection and 36 dogs with ABP. METHODS: Retrospective study. C-reactive protein concentrations and thoracic radiographs were available for each dog. RESULTS: Eleven dogs with Bb infection had alveolar lesions. In all dogs, CRP concentration was mildly increased (14-38 mg/L). In the 5 dogs without alveolar lesions, CRP concentration was within the reference range in all but 1 dog, in which it was slightly increased. Median CRP concentration was significantly higher in dogs with alveolar lesions (20 mg/L) compared with dogs without alveolar lesions (5 mg/L; p < .002). In dogs with Bb infection, median duration of clinical signs was not different between dogs with normal CRP concentration and dogs with increased concentration. In dogs with Bb infection either with or without alveolar lessions, median CRP concentration was significantly lower (20 mg/L) than in dogs with ABP (118 mg/L; p < .001). CONCLUSIONS AND CLINICAL IMPORTANCE: In contrast to dogs with APB, CRP was not a good marker for the diagnosis of dogs suspected to have bordetellosis. Confirmation of Bb infection still requires lower airway sampling.

Efficacy of Rg1-Oil Adjuvant on Inducing Immune Responses against Bordetella bronchiseptica in Rabbits.

Bordetella bronchiseptica (B. bronchiseptica) is an obligately aerobic, oxidase- and catalase-positive, nonfermentative Gram-negative coccobacillus. This study is aimed at examining the immune effects of Rg1, Rg1 plus oil, and other common adjuvants on inactivated B. bronchiseptica vaccine in rabbits. The mechanism underlying the adjuvant effect of Rg1 plus oil on the vaccine was also explored. Rg1 (100 µg) plus oil significantly improved the immune effect of B. bronchiseptica vaccine at both the humoral and cellular levels. Rg1-oil adjuvant increased the levels of IL-2 and IL-4 in rabbits after immunization. Rg1 (100 µg) plus oil also significantly increased TLR2 expression and downregulated NF-κB in splenocytes. Rg1-oil adjuvant may increase the levels of IL-2 and IL-4 via upregulating TLR2, thereby enhancing the immune effect of B. bronchiseptica vaccine. In conclusion, Rg1 plus oil could be used as a potential vaccine adjuvant for rabbit B. bronchiseptica vaccine.

Gamithromycin in swine: Pharmacokinetics and clinical evaluation against swine respiratory disease.

The pharmacokinetics of gamithromycin were evaluated in 26 male castrated and female crossbred swine administered gamithromycin 15% w/v (Zactran®, Boehringer Ingelheim) intravenously at 6 mg/kg bodyweight or intramuscularly at 3, 6 or 12 mg/kg bodyweight. Blood samples were collected up to Day 10 to establish the plasma profile of gamithromycin, bioavailability and dose proportionality. When administered by intramuscular injection at 6 mg/kg BWT, pharmacokinetic parameters were as follows: area under the curve until last quantifiable plasma concentration, 5.13 ± 0.957 µg*hours/ml; maximum plasma concentration, 960 ± 153 ng/ml at 5 to 15 min; terminal half-life of 94.1 ± 20.4 hr. Absolute bioavailability was 92.2%. Increase in systemic exposure was proportional to the gamithromycin dose level over the range 3-12 mg/kg BWT. No gender-related statistically significant difference in exposure was observed. For clinical evaluation of Zactran® against swine respiratory disease, 305 pigs from six commercial farms in three countries in Europe with signs associated with Actinobacillus pleuropneumoniae and/or Haemophilus parasuis and/or Pasteurella multocida and/or Bordetella bronchiseptica were used. At each site, animals were treated once in a 1:1 ratio with a single intramuscular dose of Zactran® (6 mg gamithromycin/kg bodyweight) or Zuprevo® (4% w/v tildipirosin at 4 mg/kg bodyweight; MSD Animal Health) at the recommended dose respectively. Animals were observed and scored daily for 10 consecutive days for signs of swine respiratory disease (depression, respiration and rectal temperature), and animals presenting signs of clinical swine respiratory disease (Depression Score 3 and/or Respiratory Score 3 associated with Rectal Temperature > 40.0°C) were removed from the study and considered as treatment failure. Animals which remained in the study were individually assessed for 'treatment success' or 'treatment failure' (Depression Score ≥ 1 and Rectal Temperature > 40.0°C or Respiratory Score ≥ 1 and Rectal Temperature > 40.0°C). Using a non-inferiority hypothesis test (non-inferiority margin = 0.10), the proportion of treatment successes in the Zactran® group (97%) was equivalent to or better than that in the Zuprevo® group (93%).

Clinical response to 2 protocols of aerosolized gentamicin in 46 dogs with Bordetella bronchiseptica infection (2012-2018).

BACKGROUND: Bordetella bronchiseptica (Bb) infection commonly causes respiratory disease in dogs. Gentamicin delivered by aerosol maximizes local drug delivery without systemic absorption but clinical response to protocols remains undetermined. OBJECTIVES: To compare the clinical response to 2 protocols of aerosolized delivery of gentamicin in bordetellosis. ANIMALS: Forty-six dogs with Bb infection confirmed by culture or quantitative polymerase chain reaction on bronchoalveolar lavage. METHODS: Retrospective study. Administration of aerosolized gentamicin for ≥10 minutes q12h for ≥3 weeks using 4 mg/kg diluted with saline (group 1) or undiluted 5% solution (group 2). Clinical response firstly assessed after 3-4 weeks and treatment pursued by 3-weeks increments if cure not reached. Cure defined as absence of cough persisting at least a week after treatment interruption. RESULTS: Demographic data were similar between both groups. Clinical cure at 3-4 weeks was more frequently observed with the use of undiluted solution (19/33 vs 3/13 dogs, P = .03) in association with a shorter median duration of treatment (4 vs 6 weeks, P = .01). Dogs from group 2 having less than 1000 cells/µL in lavage were also more likely to be cured at 3-4 weeks than dogs with more than 1000 cells/µL [9/9 vs 10/19, P = .006] and median duration of treatment in that subgroup of animals was reduced (3 vs 5 weeks, P = .02). CONCLUSION AND CLINICAL IMPORTANCE: Aerosolized delivery of gentamicin seems effective for inducing clinical cure in Bb infection. Clinical response appears better using undiluted 5% solution, particularly in the subgroup of dogs having less than 1000 cells/µL in lavage.

Characterisation of Bordetella bronchiseptica isolated from rabbits in Fujian, China.

Bordetella bronchiseptica is a potential zoonotic pathogen, which mainly causes respiratory diseases in humans and a variety of animal species. B. bronchiseptica is one of the important pathogens isolated from rabbits in Fujian Province. However, the knowledge of the epidemiology and characteristics of the B. bronchiseptica in rabbits in Fujian Province is largely unknown. In this study, 219 B. bronchiseptica isolates recovered from lung samples of dead rabbits with respiratory diseases in Fujian Province were characterised by multi-locus sequencing typing, screening virulence genes and testing antimicrobial susceptibility. The results showed that the 219 isolates were typed into 11 sequence types (STs) including five known STs (ST6, ST10, ST12, ST14 and ST33) and six new STs (ST88, ST89, ST90, ST91, ST92 and ST93) and the ST33 (30.14%, 66/219), ST14 (26.94%, 59/219) and ST12 (16.44%, 36/219) were the three most prevalent STs. Surprisingly, all the 219 isolates carried the five virulence genes (fhaB, prn, cyaA, dnt and bteA) in the polymerase chain reaction screening. Moreover, the isolates were resistant to cefixime, ceftizoxime, cefatriaxone and ampicillin at rates of 33.33%, 31.05%, 11.87% and 3.20%, respectively. This study showed the genetic diversity of B. bronchiseptica in rabbits in Fujian Province, and the colonisation of the human-associated ST12 strain in rabbits in Fujian Province. The results might be useful for monitoring the epidemic strains, developing preventive methods and preventing the transmission of epidemic strains from rabbits to humans.

Prevalence of feline herpesvirus-1, feline calicivirus, Chlamydia felis, and Bordetella bronchiseptica in a population of shelter cats on Prince Edward Island.

The prevalence of the causative agents of feline upper respiratory tract disease (URTD) has been previously documented in many regions worldwide, but has yet to be reported in eastern Canada. The objectives of this study were to determine the prevalence of feline herpesvirus-1 (FHV-1), feline calicivirus (FCV), Chlamydia felis (C. felis), and Bordetella bronchiseptica (B. bronchiseptica) in a population of shelter cats with clinical signs related to URTD on Prince Edward Island, Canada; to compare the prevalence of FHV-1 and FCV as detected by polymerase chain reaction (PCR) and virus isolation (VI) in this population; and lastly, to determine whether factors, such as co-infections, time of year, concurrent feline leukemia virus (FeLV)- or feline immunodeficiency virus (FIV)-positive status, or clinical signs, were associated with prevalence of particular pathogens. Conjunctival, nasal mucosal, and oropharyngeal swabs were collected from 82 cats with clinical signs consistent with URTD. Samples were pooled in transport medium and PCR was used to detect FHV-1, FCV, and C. felis and VI was also used to detect FHV-1 and FCV. A separate swab was submitted for aerobic bacterial culture to detect B. bronchiseptica. Feline herpesvirus-1 (FHV-1) was the most prevalent in this population, followed by C. felis, B. bronchiseptica, and FCV. Of the 4 cats that were positive for B. bronchiseptica, 3 were concurrently positive for FHV-1. All positive B. bronchiseptica cultures were resistant to cefovecin. The prevalence for FHV-1 was lowest in autumn (seasons P < 0.001) and was positively associated with the presence of nasal discharge (P = 0.018) and coughing (P = 0.043).

La prévalence des agents causals de maladies du tractus respiratoire supérieur félin (URTD) a été préalablement documentée dans plusieurs régions du monde mais n'a pas encore été rapportée dans l'est du Canada. Les objectifs de la présente étude étaient de déterminer la prévalence d'herpès virus félin-1 (FHV-1), du calicivirus félin (FCV), de Chlamydia felis et de Bordetella bronchiseptica dans une population de chats de refuge de l'Île-du-Prince-Édouard, Canada avec des signes cliniques reliés au URTD; de comparer la prévalence de FHV-1 et FCV telle que détecter par réaction d'amplification en chaîne par la polymérase (PCR) et l'isolement viral (VI) dans ces populations; et finalement, déterminer si des facteurs, tels que les co-infections, la période de l'année, le statut concomitant positif pour le virus de la leucémie féline (FeLV) ou le virus de l'immunodéficience féline (FIV) ou les signes cliniques étaient associés avec la prévalence d'un agent pathogène en particulier. Des écouvillons de la conjonctive, de la muqueuse nasale et de l'oropharynx furent obtenus de 82 chats avec des signes cliniques compatibles avec URTD. Les échantillons étaient regroupés dans un milieu de transport et la PCR utilisée pour détecter FHV-1, FCV et C. felis et l'isolement viral fut également utilisé pour détecter FHV-1 et FCV. Un écouvillon séparé fut soumis pour culture bactérienne aérobie afin de détecter B. bronchiseptica. Le FHV-1 était le plus prévalent dans cette population, suivi par C. felis, B. bronchiseptica et FCV. Des quatre chats qui étaient positifs pour B. bronchiseptica, trois étaient positifs également pour FHV-1. Tous les isolats de B. bronchiseptica obtenus étaient résistants au céfovecin. La prévalence de FHV-1 était à son plus bas en automne (P < 0,001 pour les saisons) et était associée positivement avec la présence d'écoulement nasal (P = 0,018) et de la toux (P = 0,043).(Traduit par Docteur Serge Messier).

A Study on Isolation and Molecular Identification of Bordetella avium from Iranian Commercial and Backyard Broiler Turkeys within 2016-2018.

Bordetellosis or turkey coryza, caused by Bordetella avium, has been an issue for turkey industry since its first description in 1967 when it was reported for the first time. Bordetella avium causes a highly contagious upper respiratory disease in turkeys. Therefore, this study aimed to isolate and characterize this species from commercial and backyard turkeys in Tehran, Isfahan, and Northern provinces of Iran. For the purpose of the study, 625 tracheal swabs were taken from 425 commercial poults and 200 backyard poults aged 2-6 weeks from September 2016 to September 2018. The swabs were immediately plated on MacConkey and blood agar plates and then pooled (5 swabs/pool) in tubes, containing 2 mL distilled water, to perform direct polymerase chain reaction (PCR) for the identification of B. avium. A total of 17 swab pools were found to be positive for B. avium. A subset of seven positive samples were sequenced for the flanking region of piuA gene. The analysis of the sequences indicated that the sequences were 98%, 96%, and 98% similar to B. avium 197N (AM167904.1), 4142 (AY925058.1), and 4156 (AY925068.1) sequences, respectively. To the best of our knowledge, the current study is the first attempt toward the molecular detection and characterization of B. avium in Iran. It is highly recommended to perform further studies to isolate, characterize, and differentiate the regional isolates in order to help the developing turkey industry of Iran meet the increasing demands for protein in the diet of the citizenry.

Analysis of the lung microbiota in dogs with Bordetella bronchiseptica infection and correlation with culture and quantitative polymerase chain reaction.

Infection with Bordetella bronchiseptica (Bb), a pathogen involved in canine infectious respiratory disease complex, can be confirmed using culture or qPCR. Studies about the canine lung microbiota (LM) are recent, sparse, and only one paper has been published in canine lung infection. In this study, we aimed to compare the LM between Bb infected and healthy dogs, and to correlate sequencing with culture and qPCR results. Twenty Bb infected dogs diagnosed either by qPCR and/or culture and 4 healthy dogs were included. qPCR for Mycoplasma cynos (Mc) were also available in 18 diseased and all healthy dogs. Sequencing results, obtained from bronchoalveolar lavage fluid after DNA extraction, PCR targeting the V1-V3 region of the 16S rDNA and sequencing, showed the presence of Bb in all diseased dogs, about half being co-infected with Mc. In diseased compared with healthy dogs, the ß-diversity changed (P = 0.0024); bacterial richness and α-diversity were lower (P = 0.012 and 0.0061), and bacterial load higher (P = 0.004). Bb qPCR classes and culture results correlated with the abundance of Bb (r = 0.71, P < 0.001 and r = 0.70, P = 0.0022). Mc qPCR classes also correlated with the abundance of Mc (r = 0.73, P < 0.001). Bb infection induced lung dysbiosis, characterized by high bacterial load, low richness and diversity and increased abundance of Bb, compared with healthy dogs. Sequencing results highly correlate with qPCR and culture results showing that sequencing can be reliable to identify microorganisms involved in lung infectious diseases.

Characterization of a Unique Bordetella bronchiseptica vB_BbrP_BB8 Bacteriophage and Its Application as an Antibacterial Agent.

Bordetella bronchiseptica, an emerging zoonotic pathogen, infects a broad range of mammalian hosts. B. bronchiseptica-associated atrophic rhinitis incurs substantial losses to the pig breeding industry. The true burden of human disease caused by B. bronchiseptica is unknown, but it has been postulated that some hypervirulent B. bronchiseptica isolates may be responsible for undiagnosed respiratory infections in humans. B. bronchiseptica was shown to acquire antibiotic resistance genes from other bacterial genera, especially Escherichia coli. Here, we present a new B. bronchiseptica lytic bacteriophage-vB_BbrP_BB8-of the Podoviridae family, which offers a safe alternative to antibiotic treatment of B. bronchiseptica infections. We explored the phage at the level of genome, physiology, morphology, and infection kinetics. Its therapeutic potential was investigated in biofilms and in an in vivo Galleria mellonella model, both of which mimic the natural environment of infection. The BB8 is a unique phage with a genome structure resembling that of T7-like phages. Its latent period is 75 ± 5 min and its burst size is 88 ± 10 phages. The BB8 infection causes complete lysis of B. bronchiseptica cultures irrespective of the MOI used. The phage efficiently removes bacterial biofilm and prevents the lethality induced by B. bronchiseptica in G. mellonella honeycomb moth larvae.

Specific bacteriophage of Bordetella bronchiseptica regulates B. bronchiseptica-induced microRNA expression profiles to decrease inflammation in swine nasal turbinate cells.

BACKGROUND: Respiratory diseases in pigs are the main health concerns for swine producers. Similar to the diseases in human and other animals, respiratory diseases are primary related to morbidity and are the result of infection with bacteria, viruses, or both. B. bronchiseptica causes serious respiratory diseases in the swine airway track. However, the B. bronchiseptica-specific bacteriophage has diverse advantages such as decreasing antibiotic overuse and possible therapeutic potential against bacteria. OBJECTIVE: The objects of this study were to investigate the therapeutic effect of specific B. bronchiseptica bacteriophages and to identify genes related to bacteriophage signaling utilizing RNA microarrays in swine nasal turbinate cells. METHODS: Bor-BRP-1 phages were applied 24 h prior to B.bronchiseptica infection (1 × 107 cfu/ml) at several concentrations of bacterial infection. Cells were incubated to detect cytokines and 24 h to detect mucin production. And real-time quantitative PCR was performed to examine related genes expression. To determine the change of total gene expression based on B.bronchiseptica and Bor-BRP-1 treatment, we performed RNA sequencing experiments. RESULTS: The results showed that B. bronchiseptica induced increased expression of several inflammatory genes such as IL-1ß, IL-6, and Muc1 in a dose-dependent manner. However, Bor-BRP-1 induced reduction of gene expression compared to the B. bronchiseptica induction group. In addition, microarrays detected Bor-BRP-1-altered inflammatory gene expression against B. bronchiseptica, reducing B. bronchiseptica-induced airway inflammation in swine epithelial cells. CONCLUSION: These results suggest that the specific bacteriophage has a therapeutic potential to defend against B. bronchiseptica infection by altering inflammatory gene expression profiles.

In vitro characterization and genetic diversity of Bordetella avium field strains.

Bordetella avium (BA) is a respiratory pathogen of particular importance for turkeys. Specific adherence and damage to the respiratory epithelia are crucial steps of the pathogenesis, but knowledge about the mechanisms and the variety of virulence in field strains is limited. We analysed 17 BA field strains regarding their in vitro virulence-associated properties in tracheal organ cultures (TOC) of turkey embryos, and their genetic diversity. The TOC adherence assay indicated that BA field strains differ considerably in their ability to adhere to the tracheal mucosa, while the TOC ciliostasis assay illustrated a high degree of diversity in ciliostatic effects. These two virulence-associated properties were associated with each other in the investigated strains. Three of the investigated strains displayed significantly (P > 0.05) lower in vitro virulence in comparison to other strains. Genetic diversity of BA strains was analysed by core genome multilocus sequence typing (cgMLST). We applied a cgMLST scheme comprising 2667 targets of the reference genome (77.3% of complete genome, BA strain 197N). The results showed a broad genetic diversity in BA field strains but did not demonstrate a correlation between sequence type and virulence-associated properties. The cgMLST analysis revealed that strains with less marked virulence-associated properties had a variety of mutations in the putative filamentous haemagglutinin gene. Likewise, amino acid sequence alignment indicated variations in the protein. The results from our study showed that both adherence and ciliostasis assay can be used for virulence characterization of BA. Variations in the filamentous haemagglutinin protein may be responsible for reduced virulence of BA field strains.