Salmonella is one of the leading causes of food poisoning across the world. The bacteria are also responsible for typhoid fever, which affects around 20 million people each year.
When disease-causing bacteria infect our bodies they are met with two lines of defence. The first, called the innate immune system, acts immediately, ready to fight many invaders. These locations include water, soil, insects, factory and kitchen surfaces, animal feces, and raw meats, poultry, and seafood. The bacteria can be isolated from these sources and grown. Approximately 40, salmonellosis cases with deaths are reported yearly in the U.
The number of actual cases may be 30 times higher, or more, since milder cases may not be reported or diagnosed. There are cases of typhoid fever recorded in the U. Most salmonella species infect the small intestines upon ingestion.
Illness can be caused by as few as cells. The bacteria pass through the interior lining of the small intestines and into its middle layer, causing inflammation. Identifying and understanding these phage defence systems at a molecular level could ultimately help scientists to use phage therapy approaches to cure disease. The BstA protein system has several intriguing features that have not previously been found to drive phage immunity. The aba element allows the BstA defence protein to be deactivated when the prophage needs to find a new host.
The discovery of the BstA system weaves into a tapestry of knowledge on the molecular innerworkings of viruses and cells. The findings suggest that BstA may protect Salmonella from attack by phages in the African environment, which opens up a new avenue of research for scientists.
Previous work led by Professor Jay Hinton at the University of Liverpool has provided fundamental understanding of the epidemiology, transmission and virulence of African Salmonella to drive forward the development of new treatments and vaccines.
Salmonella has the ability to punch through the tight links of cells that make up the intestinal wall, using an arsenal of proteins and toxins it can inject into cells. Sun said scientists always thought AvrA was one of these, but, as her team reported June 4 in the online journal PloS One , AvrA actually has an opposite function.
The study found that AvrA can maintain the tight structure of cell junctions in the intestinal cells, she said. AvrA temporarily stops salmonella from breaking apart the cell links.
Because the bug doesn't damage tissue during this phase, there's no inflammatory response. Instead, salmonella is mostly left alone, free to grow and multiply into a formidable invasion force.
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