Lab mice are immunized with a measles vaccine. When the mice are challenged with the measles virus to test the strength of their immunity, the memory cells do not completely prevent replication of the measles virus. The virus undergoes a few rounds of replication before the immune response is observed. You have developed a strain of mice with a much faster response to a viral challenge, but these mice often develop an autoimmune disease. Discuss the connection between the speed of response and an autoimmune disease.© BrainMass Inc. brainmass.com December 24, 2021, 10:42 pm ad1c9bdddf
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The immune system of mammals, in particular mice, have a few mechanisms for ensuring that the whatever is being attacked is supposed to be attacked. The reason why a normal strain of mice will at first experience a few rounds of replication of a virus is because a systemic response to the infection doesn't occur until a large number of antigens are detected. This provides a better sample for the immune system to accurately identify the infectious agent. Various immune cells will basically collect data about the invading pathogen. Multiple antigen-presenting cells present the antigens found on viruses, which are then recognized by various cell types such as B-cells and T-cells, and when enough of these antigens have been presented and processed, a systemic response is initiated. The more antigens are presented, the larger the sample size, the more likely the immune response will be specific to that particular antigen that stems from the virus.
If a target is identified too quickly and a response mounted to it is equally quick, there is a possibility that the immune system recognizes an antigen which isn't very specific. By that I mean, the antigen it's looking for is, indeed, the same as what viruses may present, but it is also similar enough to some membrane proteins of the organism's own cells. The immune response is therefore, looking for a non-specific target, giving it the opportunity to attack "antigen"-presenting cells which it shouldn't attack, such as it's own blood cells, let's say. This then causes systemic autoimmune diseases.
A second, similar possibility is that antigen-presenting cells will also present a number of antigens from the virus which are closely related or common to the host organism's body. If these are recognized as the target by a few immune cells, but the overall population of immune cells recognize the correct, specific antigens, then the majority of the immune response will target the virus. Contrast this to if a few immune cells target this wrong antigen, then a systemic response is initiated based on this target, then the majority of the immune system will be working to attack anything with the wrong antigen.
Hope that helps!© BrainMass Inc. brainmass.com December 24, 2021, 10:42 pm ad1c9bdddf>