Project description:Bordetella avium is thought to be strictly an avian pathogen. However, 16S rRNA gene sequencing identified 2 isolates from 2 humans with respiratory disease as B. avium and a novel B. avium-like strain. Thus, B. avium and B. avium-like organisms are rare opportunistic human pathogens.
Project description:Bordetella avium causes an upper respiratory tract disease (bordetellosis) in avian species. Commercially raised turkeys are particularly susceptible. Like other pathogenic members of the genus Bordetella (B. pertussis and B. bronchiseptica) that infect mammals, B. avium binds preferentially to ciliated tracheal epithelial cells and produces similar signs of disease. These similarities prompted us to study bordetellosis in turkeys as a possible nonmammalian model for whooping cough, the exclusively human childhood disease caused by B. pertussis. One impediment to accepting such a host-pathogen model as relevant to the human situation is evidence suggesting that B. avium does not express a number of the factors known to be associated with virulence in the other two Bordetella species. Nevertheless, with signature-tagged mutagenesis, four avirulent mutants that had lesions in genes orthologous to those associated with virulence in B. pertussis and B. bronchiseptica (bvgS, fhaB, fhaC, and fimC) were identified. None of the four B. avium genes had been previously identified as encoding factors associated with virulence, and three of the insertions (in fhaB, bvgS, and fimC) were in genes or gene clusters inferred as being absent or incomplete in B. avium, based upon the lack of DNA sequence similarities in hybridization studies and/or the lack of immunological cross-reactivity of the putative products. We further found that the genotypic arrangements of most of the B. avium orthologues were very similar in all three Bordetella species. In vitro tests, including hemagglutination, tracheal ring binding, and serum sensitivity, helped further define the phenotypes conferred by the mutations. Our findings strengthen the connection between the causative agents and the pathogenesis of bordetellosis in all hosts and may help explain the striking similarities of the histopathologic characteristics of this upper airway disease in avian and mammalian species.
Project description:Bordetella avium causes an upper-respiratory-tract disease called bordetellosis in birds. Bordetellosis shares many of the clinical and histopathological features of disease caused in mammals by Bordetella pertussis and Bordetella bronchiseptica. In this study we determined several parameters of infection in the domestic turkey, Meleagris galapavo, and compared these in vivo findings with an in vitro measure of adherence using turkey tracheal rings. In the in vivo experiments, we determined the effects of age, group size, infection duration, and interindividual spread of B. avium. Also, the effect of host genetic background on susceptibility was tested in the five major commercial turkey lines by infecting each with the parental B. avium strain and three B. avium insertion mutants. The mutant strains lacked either motility, the ability to agglutinate guinea pig erythrocytes, or the ability to produce dermonecrotic toxin. The susceptibilities of 1-day-old and 1-week-old turkeys to B. avium were the same, and challenge group size (5, 8, or 10 birds) had no effect upon the 50% infectious dose. Two weeks between inoculation and tracheal culture was optimal, since an avirulent mutant (unable to produce dermonecrotic toxin) persisted for a shorter time. Communicability of the B. avium parental strain between confined birds was modest, but a nonmotile mutant was less able to spread between birds. There were no host-associated differences in susceptibility to the parental strain and the three B. avium mutant strains just mentioned: in all turkey lines tested, the dermonecrotic toxin- and hemagglutination-negative mutants were avirulent whereas the nonmotile mutants showed no loss of virulence. Interestingly, the ability of a strain to cause disease in vivo correlated completely with its ability to adhere to ciliated tracheal cells in vitro.
Project description:Bordetella avium continues to be an economic issue in the turkey industry as the causative agent of bordetellosis, which often leads to serious secondary infections. This study presents a broad characterization of the antibiotic resistance patterns in this diverse collection of B. avium strains collected over the past thirty years. In addition, the plasmid basis for the antibiotic resistance was characterized. The antibiotic resistance pattern allowed the development of a novel enrichment culture method that was subsequently employed to gather new isolates from diseased turkeys and a healthy sawhet owl. While a healthy turkey flock was shown to seroconvert by four weeks-of-age, attempts to culture B. avium from healthy turkey poults were unsuccessful. Western blot of B. avium strains using pooled serum from diseased and healthy commercial turkey flocks revealed both antigenic similarities and differences between strains. In sum, the work documents the continued exposure of commercial turkey flocks to B. avium and the need for development of an effective, inexpensive vaccine to control spread of the disease.
Project description: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.
Project description:Bordetella avium is the etiologic agent of turkey coryza or bordetellosis, a respiratory disease responsible for substantial economic losses to the turkey industry. At present, identification of this bacterium relies on isolation and biochemical testing. Although a PCR for the detection of B. avium was proposed a number of years ago, lack of analytical verification precludes its use as a diagnostic tool. Furthermore, a number of details pertaining to the reaction conditions used are missing or unclear. In the present study we have identified an optimal set of PCR conditions for use with the previously described primer pair and determined the limit of detection under these conditions to be approximately 20 pg. Assay sensitivity is 100%, based on an analysis of 72 B. avium isolates from diverse geographic locations and covering a time span of at least 25 years. Evaluation of a separate group of 87 bacterial isolates from poultry, comprising both gram-positive and gram-negative commensals and pathogens representing 11 genera, demonstrated an assay specificity of 98.8%. Reproducibility is 100% using either purified genomic DNA or boiled cell lysates less than 3 days old. Sequence analysis of the B. avium PCR amplicons identified only three occasional sequence polymorphisms. These data indicate the B. avium PCR assay can provide clinically significant results.