User:Ziyaan Lokhandwalla/M protein (Streptococcus)

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M proteins, causes and effects.

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M protein is a virulence factor that can be produced by certain species of Streptococcus.[1] Viruses, parasites and bacteria are covered in protein and sugar molecules that help them gain entry into a host by counteracting the host's defenses. One such molecule is the M protein produced by certain streptococcal bacteria. At its C-terminus within the cell wall, M proteins embody a motif that is now known to be shared by many Gram-positive bacterial surface proteins. The motif includes a conserved hexapeptide LPXTGE, which precedes a hydrophobic C-terminal membrane spanning domain, which itself precedes a cluster of basic residues at the C-terminus.[2][3] M protein is strongly anti-phagocytic and is the major virulence factor for group A streptococci (Streptococcus pyogenes). They go by many names, as stated by Sharon Liao[1], “You may hear your doctor call them "monoclonal " proteins. They're also called monoclonal immunoglobulin, mylenoma, M spike, or paraprotein”. It binds to serum factor H, destroying C3-convertase and preventing opsonization by C3b. However plasma B cells can generate antibodies against M protein which will help in opsonization and further the destruction of the microorganism by the macrophages and neutrophils. Cross-reactivity of anti-M protein antibodies with heart muscle has been suggested to be associated in some way with rheumatic fever. Another disease more commonly caused by Streptococcus pyogenes is pharyngitis or also known as strep throat. According to Lisa Coon[2] on an article about Preventive Health, strep throat is mostly spread through droplets of contamintated person’s bodily fluids such as the saliva from a sneeze. This makes the bacteria easily transmitable from person to peson by physicial contact with these droplets. This illness can affect people in various manners, some people develop, in more severe cases, scarlet fever or scarlatina. This is expressed through the form of a rash and it can last for about a week. This can also develop with side effects such as strawberry tongue[3]. These illnesses can be considered more on the short term side of diseases that can arise. Too many M proteins present within the body and disrupting the immune system can throw off how the body defends itself therefore exposing the host to illnesses. M proteins do not have the ability to fight off infections so having an abudnace of them is not beneficial. It can lead to some long term diseases and even cancer. Long term effects can occur such as chronic infections and ​​autoimmune disorders from a disrupted immune system. This often times is why a doctor suggests patients to take urine tests for comparisons of the present population within the body and link the results to health concerns. M proteins are mimickers of the hosts’s own proteins making M proteins tricky to work with. When the immune system does manage to detect the presence of M proteins by the exposure to bacteria, the plasma B cells activate. With this plasma B cells set out to produce antibodies[4] against the M proteins. The antibodies recognize and proceed to attach to M proteins marking them for elimination by the immune cells. This can occur through a process called opsonization. The process enhances the recognition and consumption of bacteria by phagocytes, leading to their destruction. Plasma B cells are involved in the production of antibodies against M proteins produced by Streptococcus bacteria. Diseases that disguise themselves well within the host take longer to treat as it is a survival mechanism that allows for a stealthy attack. In the early 1900’s, M proteins were originally identified by Rebecca Lancefield, who also formulated the Lancefield classification system for streptococcal bacteria. Bacteria like S. pyogenes, which possess M protein are classified in group A of the Lancefield system.