Bacterial pathogens have evolved a variety of strategies to colonize and invade human organs, despite the presence of multiple host defense mechanisms. A final mechanism that pathogens can use to protect themselves towards the immune system known as antigenic variation, which is the alteration of floor proteins so that a pathogen is now not acknowledged by the host’s immune system. For example, the bacterium Borrelia burgdorferi, the causative agent of Lyme illness, contains a surface lipoprotein known as VlsE. Because of genetic recombination during DNA replication and restore, this bacterial protein undergoes antigenic variation. Each time fever happens, the VlsE protein in B.
It isn’t clear how this cytotoxic enterotoxin causes hypersecretion of water and electrolytes from the intestinal epithelium. These enterotoxins differ from those secreted by V. cholerae and E. coli in that the Shiga toxins are cytotoxic and deadly, whereas the cholera toxin-like enterotoxins are not. The latter enterotoxins trigger no structural injury to cells, and are described as cytotonic. The ensuing inflammatory response to the invading micro organism and/or their toxins appears to activate neurologic control mechanisms (e.g., prostaglandins, serotonin) that usually regulate water and electrolyte transport. Bacteria have evolved numerous structural and metabolic virulence components that improve their survival fee in the host.
Although viral pathogens aren’t similar to bacterial pathogens by way of construction, some of the properties that contribute to their virulence are comparable. Viruses use adhesins to facilitate adhesion to host cells, and sure enveloped viruses depend on antigenic variation to avoid the host immune defenses. These virulence elements are mentioned in more element in the following sections.
Salmonella is ranked among the many most important initiators of cases of food poisoning. The WHO estimates more than sixteen million international infections per 12 months, and more than half a million instances are fatal. Salmonella are present in raw food similar to eggs, meat and milk. The hazard potential is excessive, particularly in food that ought to only be barely heated or by no means heated (e.g. raw milk cheese, raw sausage, chocolate, ice cream).