Brucella suis
| Brucella suis | |
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| Brucella suis culture | |
| Scientific classification | |
| Domain: | Bacteria |
| Phylum: | Proteobacteria |
| Class: | Alphaproteobacteria |
| Order: | Rhizobiales |
| Family: | Brucellaceae |
| Genus: | Brucella |
| Species: | B. suis |
| Binomial name | |
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Brucella suis |
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Absent Serologic evidence Confirmed infections |
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Swine brucellosis is a zoonosis affecting pigs, caused by the bacterium Brucella suis. The disease typically causes chronic inflammatory lesions in the reproductive organs of susceptible animals or orchitis, and may even affect joints and other organs. The most common symptom is abortion in pregnant susceptible sows at any stage of gestation. Other manifestations are temporary or permanent sterility, lameness, posterior paralysis, spondylitis, and abscess formation. It is transmitted mainly by ingestion of infected tissues or fluids, semen during breeding, and suckling infected animals.
Since brucellosis threatens the food supply and causes undulant fever,Brucella suis and other Brucella species (B. melitensis, B. abortis, B. ovis, B. canis) are recognized as potential agricultural, civilian, and military bioterrorism agents.
B. suis is a Gram-negative, facultative, intracellular coccobacillus, capable of growing and reproducing inside of host cells, specifically phagocytic cells. They are also not spore-forming, capsulated, or motile.Flagellar genes, however, are present in the B. suis genome, but are thought to be cryptic remnants because some were truncated and others were missing crucial components of the flagellar apparatus. Interestingly, in mouse models, the flagellum is essential for a normal infectious cycle, where the inability to assemble a complete flagellum leads to severe attenuation of the bacteria.
B. suis is differentiated into five biovars (strains), where biovars 1-3 infect wild boar and domestic pigs, and biovars 1 and 3 may cause severe diseases in humans. In contrast, biovar 2 found in wild boars in Europe shows mild or no clinical signs and cannot infect healthy humans, but does infect pigs and hares.
Phagocytes are an essential component of the host’s innate immune system with various antimicrobial defense mechanisms to clear pathogens by oxidative burst, acidificiation of phagosomes, and fusion of the phagosome and lysosome. B. suis, in return, has developed ways to counteract the host cell defense to survive in the macrophage and to deter host immune responses.
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Wikipedia