The Evolution and Mechanism of Immunological Memory and its Impact on Immunology Research.
Recently, the Center for Disease and Control reported that it has discovered a super bug, a bacteria, that has the capability of resisting almost any antibiotic known to human. In addition to resisting antibiotics, these superbugs are deadly. Not only do the bugs cause death to half of the patients with serious infectious diseases, but they also spread their genes that make the bugs resistant to other bacteria cells (USA TODAY, 2013). This class of superbugs is known as carbapenem-resistant enterobacteriaceae (CRE). Currently, CRE are found mainly in hospitals and nursing homes. However, if these bacteria escape into the environment, the results can be devastating. For instance, the bacteria may cause small diseases, such as the common cold, to become untreatable because the CRE alters the small disease genetics in a way where it is resistant to vaccination and other medicines (USA TODAY, 2013). Although this type of bacteria is new and deadly, it is not the first time that the world has encountered something similar to CRE. For instance, Staphylococcus aureus is one of the well-known examples of bacteria that are resistant to antibiotics. One reason doctors use antibiotics is because bacteria are often resistant to the immune system of a body. The resistance of bacteria to the immune system is due to natural selection and genetic mutation. Because bacteria reproduce at a rapid rate, some bacteria that contain the adaptive, resistant traits survive and reproduce offspring that contains the resistant genes. They produce immune-resistant genes through genetic mutation. The alteration made by the genetic mutation can create a trait that is resistant to the immune system. As a result, the genetically mutated bacteria will be able to reproduce without interference from the host’s defense system. As a powerful tool that the body uses to protect itself from pathogens and bacteria, the immune system consist of several parts, and the immunological memory is one of the most important. Understanding the evolution and the mechanism of both the immune system and immunological memory, new research areas can be developed and new vaccines can be created that target the immune systems of pathogens or that alter the immune system to make it more efficient in combating pathogens. Evolution of the innate immune system and the innate memory Organisms of the same species’ innate memory are almost the same. This memory comes from millions of years of evolution (Sompayrac, 2008). The immunological innate memory is based on pattern recognition receptors. Pattern recognition receptors are the main components that allow the innate immune system to recognize the pathogens and activate antigens (Kurtz, 2004). These receptors have gone through millions of years of evolution. One of the main receptors is the Toll-like receptors (TLRs) (Sompayrac, 2008). Instead of studying the body’s defense to pathogens, current research investigate the evolution of the innate immune system through observing the examples of specific receptors in simple organisms. Wu and Huan (2011) are studying the Toll/interleukin-1 receptor (TIR) and the leucine-rich repeat (LRR), which are the two domains that make up the TLR. TIR and LRR are connected by a transmembrane helical starch that is 20 amino acids long. TIR plays an important role in activating the innate immune system by detecting lipopolysaccharide from gram-negative bacteria. The interaction between the receptors of both the innate immune system and bacteria is handled by LRR.
Figure 1: Illustration of evolutionary tree of invertebrates. Amphimedon came before Cnidarians. (Wu and Huan 2011)
To understand the evolution of TLR, scientists have to discover when the TIR and LRP first appeared. One research conducted by Dr. Wu and coworkers (2011) attempted to create a phylogenetic tree of the TLR. After comparing the...
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