Characterization of Temperate LPS-Binding Bordetella avium Phages That Lack Superinfection Immunity.

Bordetella avium causes a highly infectious upper respiratory tract disease in turkeys and other poultry with high economic losses. Considering the antimicrobial resistance crisis, bacteriophages (phages) may be an alternative approach for treating bacterial infections such as bordetellosis. Here, we describe seven B. avium phages, isolated from drinking water and feces from chicken and turkey farms. They showed strong bacteriolytic activity with a broad host range and used lipopolysaccharides (LPS) as a host receptor for their adsorption. All phages are myoviruses based on their structure observed by transmission electron microscopy. Genome sequence analyses revealed genome assembly sizes ranging from 39,087 to 43,144 bp. Their permutated genomes were organized colinearly, with a conserved module order, and were packed according to a predicted headful packing strategy. Notably, they contained genes encoding putative markers of lysogeny, indicative of temperate phages, despite their lytic phenotype. Further investigation revealed that the phages could indeed undergo a lysogenic life cycle with varying frequency. However, the lysogenic bacteria were still susceptible to superinfection with the same phages. This lack of stable superinfection immunity after lysogenization appears to be a characteristic feature of B. avium phages, which is favorable in terms of a potential therapeutic use of phages for the treatment of avian bordetellosis. IMPORTANCE To maintain the effectiveness of antibiotics over the long term, alternatives to treat infectious diseases are urgently needed. Therefore, phages have recently come back into focus as they can specifically infect and lyse bacteria and are naturally occurring. However, there is little information on phages that can infect pathogenic bacteria from animals, such as the causative agent of bordetellosis of poultry, B. avium. Therefore, in this study, B. avium phages were isolated and comprehensively characterized, including whole-genome analysis. Although phenotypically the phages were thought to undergo a lytic cycle, we demonstrated that they undergo a lysogenic phase, but that infection does not confer stable host superinfection immunity. These findings provide important information that could be relevant for potential biocontrol of avian bordetellosis by using phage therapy.

Characterisation of novel microbial strains Proteus mirabilis and Bordetella avium for heavy metal bioremediation and dye degradation.

The entitled study focuses on exploring the microbial diversity and its applicability in the remediation of metal contaminated soil using microbes, which is a reliable and cost effective technique. Tungsten enriched soil of Kuhi-Agargaon-Khobna region (Nagpur, India) were analysed by XRF method to detect heavy metals. The traditional microbiological techniques were used to isolate tungsten tolerant microbes. Applicability of these microbes in bioremediation and Azo dye degradation was mainly studied. The two novel bacterial strains, Proteus mirabilis (RS2K) and Bordetella avium (RS3K), were isolated and identified to show the tolerance to tungsten, using 16S rDNA and phylogenetic analysis. These novel strains have also shown the tolerance to other metallic salts viz., (sodium) tungsten, tungstic acid, ammonium metaparatungstate, mercuric chloride, cobalt chloride and azo dye. These microbes were found to accumulate tungsten intracellularly as confirmed through ICP-MS and SEM-EDS analyses. Microbes exhibited well-equipped cellular mechanisms for metal tolerance to survive in heavy metal-laden ecology. Current study contains substantial potential in bioleaching of heavy metals and green mining along with Nano bioremediation for heavy metal pollution.

Development of a harmonized method for antimicrobial susceptibility testing of Bordetella avium using broth microdilution and detection of resistance genes.

AIMS: In response to a request from the Clinical and Laboratory Standards Institute (CLSI), the objective of this study was to develop a harmonized method for broth microdilution susceptibility testing of Bordetella (B.) avium, the major causative agent of infectious coryza in poultry. METHODS AND RESULTS: To find a suitable test medium, growth curves with four epidemiologically unrelated B. avium isolates were created in cation-adjusted Mueller-Hinton broth (CAMHB), CAMHB + 2.5% lysed horse blood and veterinary fastidious medium. All isolates showed good growth in CAMHB, therefore MIC values were determined using this medium and the homogeneity of the values was determined. An essential MIC agreement of 99.7% was calculated. Testing of a larger strain collection (n = 49) for their susceptibility to 24 antimicrobials confirmed the suitability of the tested method and revealed some isolates with elevated MICs of florfenicol (n = 1), streptomycin (n = 2), tetracyclines (n = 5), and trimethoprim/sulfamethoxazole (n = 6). PCR assays detected the resistance genes aadA1, dfrB1, floR, sul1, sul2 and tet(A). CONCLUSIONS: The method used enables easy reading and a good reproducibility of MIC values for B. avium. SIGNIFICANCE AND IMPACT OF STUDY: Application of the tested method allows harmonized resistance testing of B. avium and identification of isolates with elevated MIC values.

Bordetella avium-associated endophthalmitis: case report.

BACKGROUND: Bordetella avium, an aerobic bacterium that rarely causes infection in humans, is a species of Bordetella that generally inhabits the respiratory tracts of turkeys and other birds. It causes a highly contagious bordetellosis. Few reports describe B. avium as a causative agent of eye-related infections. CASE PRESENTATION: We report a case of acute infectious endophthalmitis associated with infection by B. avium after open trauma. After emergency vitrectomy and subsequent broad-spectrum antibiotic treatment, the infection was controlled successfully, and the patient's vision improved. CONCLUSIONS: B. avium can cause infection in the human eye, which can manifest as acute purulent endophthalmitis. Nanopore targeted sequencing technology can quickly identify this organism. Emergency vitrectomy combined with lens removal and silicone oil tamponade and the early application of broad-spectrum antibiotics are key for successful treatment.

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.

Prevalence, virulence attributes, and antibiogram of Bordetella avium isolated from turkeys in Egypt.

Turkey coryza is a major respiratory disease caused by Bordetella avium (B. avium). It occurs in all ages of turkeys and is characterized by high morbidity and low mortality rates. The present study aimed firstly at determination of the prevalence rates of B. avium in turkeys reared in Egypt at different ages using various diagnostic methods including clinical examination, histopathology, enzyme-linked immunosorbent assay (ELISA), bacterial culture, and polymerase chain reaction (PCR). Using PCR, virulence-associated genes were detected in the confirmed B. avium isolates. Furthermore, the antibiotic resistance profiles of the confirmed B. avium isolates were examined. The achieved results indicated isolation and identification of B. avium infection at different ages of turkeys reared in Egypt. The overall PCR-confirmed prevalence rate of B. avium was 22.95%. The identified B. avium strains harbored virulence-associated genes responsible for colonization in the respiratory tract of turkeys including Bordetella virulence gene (100%), fimbriae (71.14%), and filamentous hemagglutinin (85.68%). The isolated B. avium strains showed multidrug resistance profiles. B. avium isolates were resistant to penicillin (92.82%), ceftiofur (85.68%), nalidixic acid (78.54%), and lincomycin (71.40%). The identified B. avium strains showed clear sensitivities to both gentamicin and neomycin, suggesting these as possible antimicrobial candidates for the control of B. avium infection in turkeys.

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.

Establishment of a Bordetella avium challenge model in turkeys.

Despite the importance of Bordetella avium (BA) as a respiratory pathogen of young turkeys, no infection model for the evaluation of BA-vaccine efficacy is available. The objective of this study was to evaluate the influence of route and dose of infection on the establishment of a BA-challenge model. In our first experiment, 28-day-old turkeys were either inoculated oculonasally with 105, 107 or 109 colony forming units (CFU) of BA per bird or exposed to BA by aerosol with 105-108 CFU/m3. The respiratory tract of all inoculated birds was BA-colonized, which was confirmed by choanal swabs and samples of trachea and lung, showing the highest prevalence in the aerosol-inoculated group. BA-specific humoral immune response was detected in the form of IgG in serum from five days post infection (dpi) and IgA in lacrimal fluid from seven dpi. In the second experiment, the model was tested in a vaccination trial. Twenty-one-day-old turkeys were vaccinated with a formalin-inactivated BA vaccine intramuscularly and challenged 21 days post vaccination with 107 CFU per bird oculonasally. BA-specific IgG antibodies were detected in serum and in lacrimal fluid 14 days post vaccination. As in the first experiment, secretory BA-specific antibodies of the IgA isotype were only detected in the inoculated groups from seven dpi. Despite the lack of clinical signs or pathological alterations in both experiments, vaccine efficacy was demonstrated by significant reduction in BA colonization of the trachea (P ≤ 0.05). In our study, a reliable model for BA infection has been established and has been demonstrated to be suitable for evaluation of vaccine efficacy.

Detection of Bordetella avium by TaqMan real-time PCR in tracheal swabs from wildlife birds.

Bordetella avium, the causing agent of bordetellosis, a highly contagious infection of the respiratory tract in young poultry, causes significant losses in poultry farming throughout the world. Wildlife birds can be a reservoir of various pathogens that infect farm animals. For this reason the studies were conducted to estimate the prevalence of Bordetella avium in wildlife birds in Poland. Tracheal swab samples were collected from 650 birds representing 27 species. The bacterial DNA was isolated directly from the swabs and screened for Bordetella avium by TaqMan real-time PCR. The assay specificity was evaluated by testing DNA isolated from 8 other bacteria that can be present in avian respiratory tract, and there was no amplification from non-Bordetella avium agents. Test sensitivity was determined by preparing standard tenfold serial dilutions of DNA isolated from positive control. The assay revealed to be sensitive, with detection limit of approximately 4.07x10^2 copies of Bordetella avium DNA. The genetic material of Bordetella avium was found in 54.54% of common pheasants, in 9.09% of Eurasian coots, in 3.22% of black-headed gulls and in 2.77% of mallard ducks. The results of this study point to low prevalence of Bordetella avium infections in wildlife birds. The results also show that described molecular assay proved to be suitable for the rapid diagnosis of bordetellosis in the routine diagnostic laboratory.

Biofilm formation and cellulose expression by Bordetella avium 197N, the causative agent of bordetellosis in birds and an opportunistic respiratory pathogen in humans.

Although bacterial cellulose synthase (bcs) operons are widespread within the Proteobacteria phylum, subunits required for the partial-acetylation of the polymer appear to be restricted to a few γ-group soil, plant-associated and phytopathogenic pseudomonads, including Pseudomonas fluorescens SBW25 and several Pseudomonas syringae pathovars. However, a bcs operon with acetylation subunits has also been annotated in the unrelated ß-group respiratory pathogen, Bordetella avium 197N. Our comparison of subunit protein sequences and GC content analyses confirms the close similarity between the B. avium 197N and pseudomonad operons and suggests that, in both cases, the cellulose synthase and acetylation subunits were acquired as a single unit. Using static liquid microcosms, we can confirm that B. avium 197N expresses low levels of cellulose in air-liquid interface biofilms and that biofilm strength and attachment levels could be increased by elevating c-di-GMP levels like the pseudomonads, but cellulose was not required for biofilm formation itself. The finding that B. avium 197N is capable of producing cellulose from a highly-conserved, but relatively uncommon bcs operon raises the question of what functional role this modified polymer plays during the infection of the upper respiratory tract or survival between hosts, and what environmental signals control its production.

Immuno-enhancement of Taishan Pinus massoniana pollen polysaccharides on recombinant Bordetella avium ompA expressed in Pichia pastoris.

Bordetellosis, caused by Bordetella avium, continues to be an economic problem in the poultry industry of China. Vaccines with good protective ability are lacking. Thus, developing a novel vaccine against the B. avium infection is crucial. Here, we constructed a recombinant Pichia pastoris transformant capable of expressing the outer membrane protein A (ompA) of B. avium to prepare the recombinant ompA subunit vaccine and then evaluated its immune effects. To further investigate the immunomodulation effects of Taishan Pinus massoniana pollen polysaccharides (TPPPS) on this subunit vaccine, three concentrations (20, 40, and 60 mg/mL) of TPPPS were used as the adjuvants of the ompA subunit vaccine respectively. The conventional Freund's incomplete adjuvant served as the control of TPPPS. Chickens in different groups were separately vaccinated with these vaccines thrice. During the monitoring period, serum antibody titers, concentrations of serum IL-4, percentages of CD4(+) and CD8(+) T-lymphocytes in the peripheral blood, lymphocyte transformation rate, and protection rate were detected. Results showed that the pure ompA vaccine induced the production of anti-ompA antibody, the secretion of IL-4, the increase of CD4(+) T-lymphocytes counts and lymphocyte transformation rate in the peripheral blood. Moreover, the pure ompA vaccine provided a protection rate of 71.67% after the B. avium challenge. Notably, TPPPS adjuvant vaccines induced higher levels of immune responses than the pure ompA vaccine, and 60 mg/mL TPPPS adjuvant vaccine showed optimal immune effects and had a 91.67% protection rate. Our findings indicated that this recombinant B. avium ompA subunit vaccine combined with TPPPS had high immunostimulatory potential. Results provided a new perspective for B. avium subunit vaccine research.

Epidemiological situation of turkey coryza (bordetellosis) in Poland.

The present study investigated the prevalence of Bordetella avium (BA) infections in turkey flocks of different production type in Poland, based on serological examination of blood samples collected between 2012 and 2014. The results of our study indicate that BA infections are very common in turkey flocks, they are possible during the whole production cycle and that probability of the past infection increases with age. This situation is causing high level of specific anti-BA maternally derived antibody transfer to hatching poults.

Co-adjuvant effects of plant polysaccharide and propolis on chickens inoculated with Bordetella avium inactivated vaccine.

Taishan Pinus massoniana pollen polysaccharide (TPPPS), propolis (PP) and aloe polysaccharide (AP), used as adjuvants, have been proven to possess immunity-enhancing functions. However, their collaborative immunomodulatory effects are largely unknown. To determine which combination can induce the best effects, the three adjuvants were separately or conjointly added into Bordetella avium inactivated vaccines to investigate their co-adjuvant effects on vaccinated chickens. We found that, among all six adjuvant-treated vaccine inoculated groups (TPPPS, PP, AP, TPPPS-PP, PP-AP and TPPPS-AP), the chickens inoculated with TPPPS, PP or TPPPS-PP adjuvant vaccines showed significantly higher levels of antibody titre, cytokine, lymphocyte transformation and peripheral blood T-lymphocyte count than those of non-adjuvant vaccine inoculated groups (P < 0.05), indicating the good immune-enhancing effects of TPPPS and PP. The TPPPS-PP group showed the highest levels of antibody titres and interleukin-2 (IL-2) at 14-28 days post the first inoculation (dpi), lymphocyte transformation rates (LTRs) at 14-35 dpi, CD4(+) T-lymphocyte counts at 14-42 dpi, and CD8(+) T-lymphocyte counts at 28 dpi. The results revealed that B. avium inactivated vaccine used conjointly with TPPPS and PP induced the strongest humoral and cellular immune responses. Thus, there was a synergistic effect between TPPPS and PP on enhancing immunity, which suggests that they can be used as a novel adjuvant formulation for the development of poultry vaccines.

Effects of polysaccharide on chicks co-infected with Bordetella avium and Avian leukosis virus.

Chicks' co-infection with immunosuppressive virus and bacteria seriously threaten the development of the poultry industry. In this study, a model was established in which chicks were injected with either subgroup B ALV (ALV-B)+Bordetella avium (B. avium), or ALV-B+B. avium+Taishan Pinus massoniana pollen polysaccharide (TPPPS), or B. avium only, or B. avium+TPPPS. The data showed that the group injected with ALV-B and B. avium exhibited significant inhibition of the immune function and therefore increased pathogenicity compared with the group injected with B. avium-only. Application of TPPPS effectively alleviated immunosuppression, and body weights increased sharply in the TPPPS groups compared with non-TPPPS groups. To some extent, TPPPS may reduce the proliferation of ALV-B. These results suggest that Pinus pollen polysaccharides are beneficial treating co-infections with immunosuppressive virus and bacteria and therefore have potential for development into safe and effective immunoregulator.

Immunoregulatory effects of Taishan Pinus massoniana pollen polysaccharide on chicks co-infected with avian leukosis virus and Bordetella avium early in ovo.

In recent years, co-infection of chicken embryos with immunosuppressive viruses and bacteria occurs with an annually increasing frequency. Consequently, studies on new and safe immunoregulators, especially plant polysaccharides, have become a popular topic in the poultry industry. In the present study, we selected 300 specific pathogen free embryonated eggs, which were injected with subgroup B avian leukosis virus (ALV-B) and Bordetella avium (B. avium) to establish an artificial co-infection model. The chicks that hatched from these co-infected embryonated eggs were treated with Taishan Pinus massoniana pollen polysaccharide (TPPPS). Results indicated that relevant indices in the co-infection group were significantly lower than that in B. avium-only group. Furthermore, pathogenicity of B. avium was exacerbated, with the chicks exhibiting decreased body weights. The TPPPS groups exhibited gradual improvements in immune function and developmental status. Therefore, in terms of improving immunologic function and production performance, TPPPS could be used as immunoregulator for immune responses.

Complete Bordetella avium, Bordetella hinzii and Bordetella trematum lipid A structures and genomic sequence analyses of the loci involved in their modifications.

Endotoxin is recognized as one of the virulence factors of the Bordetella avium bird pathogen, and characterization of its structure and corresponding genomic features are important for an understanding of its role in pathogenicity and for an improved general knowledge of Bordetella spp virulence factors. The structure of the biologically active part of B. avium LPS, lipid A, is described and compared to those of another bird pathogen, opportunistic in humans, Bordetella hinzii, and to that of Bordetella trematum, a human pathogen. Sequence analyses showed that the three strains have homologues of acyl-chain modifying enzymes PagL, PagP and LpxO, of the 1-phosphatase LpxE, in addition to LgmA, LgmB and LgmC, which are required for the glucosamine modification. MALDI mass spectrometry identified a high amount of glucosamine substituting the phosphate groups of B. avium lipid A; this modification was absent from B. hinzii and B. trematum. The acylation patterns of the three lipid As were similar, but they differed from those of Bordetella pertussis and Bordetella parapertussis. They were also found to be close to the lipid A structure of Bordetella bronchiseptica, a mammalian pathogen, only differing from the latter by the degree of hydroxylation of the branched fatty acid.

Taishan Pinus massoniana pollen polysaccharides promote immune responses of recombinant Bordetella avium ompA in BALB/c mice.

To study the effects of Taishan Pinus massoniana pollen polysaccharides (TPPPS) on Bordetella avium outer membrane protein A (ompA) recombinant protein vaccine, ompA was expressed, confirmed by Western blotting and mixed with TPPPS. Female BALB/c mice were randomly divided into six groups (I-VI). Groups I, II, and III were treated with TPPPS-ompA at doses of 200, 400, and 800 mg/ml, respectively. Groups IV, V, and VI were treated with Freund's adjuvant-ompA, pure ompA, and physiological saline, respectively. On days 3, 7, 14, 21, 28, 35, 42, and 49 after the first vaccination, antibody titers, interleukin-2 (IL-2) levels, peripheral blood CD4+ and CD8+ levels, and T lymphocyte proliferation rates in peripheral blood, as well as secreting-type immunoglobulin A (SIgA) levels in the duodenum, were measured. The antibody titers against ompA, IL-2, T lymphocyte proliferation rate, CD4+, and CD8+ in Group II were significantly (P<0.05) higher than those in other groups. However, little difference in SIgA content was observed among Groups I, II, and IV. These results indicated that TPPPS strengthened humoral and cellular immune response against recombinant ompA vaccine and 400 mg/ml TPPPS showed significance (P<0.05) compared with Freund's adjuvant. Therefore, TPPPS can be developed into an adjuvant for recombinant protein vaccines or plant-derived medicine for animal husbandry.

Monoclonal antibodies directed against the outer membrane protein of Bordetella avium.

Bordetella avium is the etiologic agent of coryza and rhinotracheitis in poultry. This respiratory disease is responsible for substantial economic losses in the poultry industry. Monoclonal antibodies (MAbs) were produced against the outer membrane proteins (OMPs) of B. avium isolated from diseased chickens. BALB/c mice were immunized with the extracted B. avium OMPs. Then the splenocytes from immunized mice and SP2/0 myeloma cells were fused using PEG 4000. Three stable hybridoma clones (designated as 3G10, 4A3, and 4E8) were produced via indirect ELISA and three rounds of subcloning. The MAbs were classified as IgG1, and can recognize the 58 kDa OMP band by Western blot assays. No MAb cross-reactivity with chicken Proteus mirabilis, Escherichia coli, and Salmonella was observed. A double antibody sandwich ELISA (DAS-ELISA) was developed using the rabbit polyclonal antibodies as the capture antibody and MAb 4A3 as the detection antibody. Under the DAS-ELISA, the minimum detectable concentration of B. avium was 1 × 10(4) CFU/mL, and no cross-reactivity occurred with chicken Proteus mirabilis, Escherichia coli, and Salmonella. Results showed that the DAS-ELISA has good sensitivity and specificity. Clinical application showed the DAS-ELISA was more sensitive than the plate agglutination test. This study may be used to develop a quick and specific diagnostic kit, analyze epitopes, and establish systems for typing B. avium.

Pathogenicity of Bordetella avium under immunosuppression induced by Reticuloendotheliosis virus in specific-pathogen-free chickens.

Multiple infections of Bordetella avium (B. avium) with virus, especially immunosuppressive virus, have become more and more severe in chickens in China. The increasing morbidity and mortality of its complications have amplified concerns about the impact of B. avium on animal health. To evaluate the pathogenicity of B. avium under immunosuppression status, we developed four types of Reticuloendotheliosis virus (REV) infection models. After a comparison of body weight, relative immune organ index, Newcastle disease virus antibody titers and lymphocyte ratio, we chose the early age with low dose infection as our immunosuppressive model. To investigate the pathogenicity of B. avium under this model, a study was completed in which chickens were inoculated with REV-only, B. avium-only, both agents (REV -B. avium) or first inoculated with REV and 5 d later with B. avium (REV/B. avium). Results revealed that antibody titers to B. avium, concentrations of IFN-γ and SIgA were decreased in coinfected chickens when compared to the B. avium-only chickens, but the changing trend was similar between REV/B. avium and B. avium-only groups. Overall, REV did enhance the pathogenicity of B. avium. However, B. avium-only did not cause severe immune dysfunction unless chicks were coinfected with REV. REV preceding infection with B. avium showed mild impairment, which needs further exploration.

Virulence and molecular aspects of Bordetella avium isolated from cockatiel chicks (Nymphicus hollandicus) in Brazil.

Bordetella avium is an opportunistic pathogen that presents tropism for ciliated epithelia, leading to upper respiratory tract disease in turkeys. This agent has also been associated with Lockjaw Syndrome in psittacine birds, but literatures describing the importance of this agent in such species are rare. The purpose of the present study was to report the first outbreak of B. avium infection in juvenile cockatiels demonstrating the Lockjaw Syndrome in Brazil and to investigate the antimicrobial resistance profile and phenotypic and genotypic characteristics of these strains. Surprising, the strains obtained from five infected cockatiel chicks from three different breeders from different Brazilian states showed a clonal relationship using the Pulsed Field Gel Electrophoresis and Single Enzyme Amplified Fragment Length Polymorphism techniques. The virulence potentials of the B. avium strains were assessed using tracheal adherence and cytotoxic effects on a VERO cell monolayer.