User:Schuylerjones

From MicrobeWiki, the student-edited microbiology resource

Ex. [[]]

Characteristics of the symbiont/pathogen

Bordetella bronchiseptica, stain RB50, is a small (0.4 by 8.0 um), gram negative, rod shaped beta-proteobacteria belonging to the Bordetellae family. B. bronchiseptica is nonsporeforming and pleomorphic, with or without flagella depending on the environment for which motility is needed. The average diameter of the flagella when present is 13.9 nm. B. bronchiseptica bacteria colonize within the respiratory tracts of mammals, commonly canines and felines, causing tracheobronchitis also known as "kennel cough". B. bronchiseptica is closely related to Bordetella pertussis and Bordetella parapertussis, which causes pertussis or whooping cough in humans [2]. B. bordetella does not express the pertussis toxin, the virulence factor of B. pertussis. However, B. bordetella has the genes to express the toxin which shows that B. bordetella is very closely related to B. pertussis [4].


B. bronchiseptica consists of 5,339,179 base pairs with 5,011 coding sequences. Its average gene size is 982 bp and it has 18 pseudogenes. The gene responsible for virulence is BvgAS [6].

Characteristics of the host

Bordetella bronchiseptica [1]

"Bordetella bronchiseptica" can infect a wide range of hosts causing different diseases and is most commonly found in canines, pigs, and laboratory animals [2]. B. bronchiseptica infects its host by attaching to hamster lung fibroblasts when inhaled [4]. The bacterium is capable of living outside of a host most likely in areas where animals are kept in close confinement. B. brochiseptica causes swine atrophic rhinitis and pneumonia in pigs, deforming and stunting the growth of the turbinates in the snout. B. brochiseptica is the primary pathogen of swine. B. bronchiseptica causes acute tracheobronchitis, otherwise known as kennel cough, in cats and dogs. It is unknown whether B. bronchiseptica is passed from farm to companion animals [2] and humans are rarely infected [4].

Host-Symbiont Interaction

The interaction between B. bronchiseptica and its host is pathogenic. Infection of B. bronchiseptica causes kennel cough in canines and is of high morbidity and low mortality [2]. The bacterium is characterized as a facultative parasite in which it is capable of surviving for an extensive amount of time outside of a host. The host acquires B. bronchiseptica when exposed to an infected surface, specifically where an already infected host has been. Usually canines come in contact with the bacterium when boarded in a close confined area such as a kennel. The host inhales B. bronchiseptica and colonizes on the muccous membranes lining the respiratory tract and produces factors that counteract the host's defense mechanisms. B. bronchiseptica infects healthy ciliated epithelial cells whereas most respiratory pathogens cannot. A host transmits the symbiont by coughing and therefore infected a surface. As the host's defenses become weak, they are vulnerable to other infections. [5].

Molecular Insights into the Symbiosis

Describe molecular/genetic studies on the symbiosis.

B. bronchiseptica expresses many protein factors, such as filamentous haemagglutinin (FHA), pertactin and fimbriae. Moreover, cultivating toxins such as bifunctional adenylate cyclase and dermonecrotic toxins. All of these factors allow for B. brochiseptica to weaken the host's immune defenses, leading to infection. BvgA and BvgS regulate these virulence factors [5].

Ecological and Evolutionary Aspects

What is the evolutionary history of the interaction? Do particular environmental factors play a role in regulating the symbiosis?

Recent Discoveries

Describe two findings on the symbiosis published within the last two years.

References

[[2] Binns, S. H., Corkill, J. E., Dawson, S., Gaskell, R. M., Hart, C. A., Kariuki, S., Osborn, A. M., Saunders, J. R., and Speakman, A. J. 1997. Characterization of antibiotic resistance plasmids from "Bordetella bronchiseptica". Journal of Antimicrobial Chemotherapy. 40: 811-816.]

[[3] Appel J. G. M., Bemis, A. D., and Greisen, A. H. 1977. Pathogenesis of canine bordetellosis. The Journal of Infectious Diseases. 135: 753-762.]

[[4] Goodnow, R. 1980. Biology of "Bordetella bronchiseptica". Microbiological Reviews. 44: 722-738.]

[[5] Roberts, M., and Stevenson, A. 2003. Use of "Bordetella bronchiseptica" and "Bordetella pertussis" as live vaccines and vectors for heterologous antigens. FEMS Immunology and Medical Microbiology. 37: 121-128.]

[[6] Arico, B. and Rappuoli, R. "Bordetella parapertussis" and "Bordetella bronchiseptica" contain transcriptionally silent pertussis toxin genes. 1987. Journal of Bacteriology. 169: 2847-2853.]

Edited by [Schuyler Jones], students of Grace Lim-Fong