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Antigenic variation or antigenic alteration refers to the mechanism by which an infectious agent such as a protozoan, bacterium or virus alters the proteins or carbohydrates on its surface and thus avoids a host immune response, making it one of the mechanisms of antigenic escape. It is related to phase variation. Antigenic variation not only ...
The process of V(D)J recombination is mediated by VDJ recombinase, which is a diverse collection of enzymes. The key enzymes involved are recombination activating genes 1 and 2 (RAG), terminal deoxynucleotidyl transferase (TdT), and Artemis nuclease, a member of the ubiquitous non-homologous end joining (NHEJ) pathway for DNA repair. [4]
The classical pathway is distinct from the other complement pathways in its unique activation triggers and cascade sequence. Activation of the complement pathway through the classical, lectin or alternative complement pathway is followed by a cascade of reactions eventually leading to the membrane attack complex.
The alternative pathway is a type of cascade reaction of the complement system and is a component of the innate immune system, a natural defense against infections. The alternative pathway is one of three complement pathways that opsonize and kill pathogens. The pathway is triggered when the C3b protein directly binds a microbe. It can also be ...
Memory T cells also make use of this pathway and have higher levels of Lck expressed and the function of Csk is inhibited in these cells. [ 14 ] The binding of the antigen-MHC to the TCR complex and CD4 may also help the APC and the T h cell adhere during T h cell activation, but the integrin protein LFA-1 on the T cell and ICAM on the APC are ...
The Wnt pathway is involved in all stages of differentiation, and the ligand Wnt3a can substitute for the overexpression of c-Myc in the generation of induced pluripotent stem cells. [40] On the other hand, disruption of β-catenin , a component of the Wnt signaling pathway, leads to decreased proliferation of neural progenitors.
Some antigens may even target pathways different from those the vaccine had originally intended to target. [4] Recent research on many vaccines, including the malaria vaccine, has focused on how to anticipate this diversity and create vaccinations that can cover a broader spectrum of antigenic variation. [5]
Antigenic drift occurs in both influenza A and influenza B viruses. (Confusion can arise with two very similar terms, antigenic shift and genetic drift. Antigenic shift is a closely related process; it refers to the more dramatic changes in the virus's surface proteins when the genetic material from two or more viruses mix together.