On pages 125-126, Dr. Moalem described the first discovery of a vaccine by Dr. Jenner after he noticed that milkmaids with cowpox were more resistant to the deadly disease, smallpox, compared to other people within the same community. This relates to Big Idea 3: Living systems store, retrieve, transmit, and respond to information essential to life processes.
From the information from this experiment, explain what vaccination is in your own words. Determine why Dr. Jenner used a scrape of a cowpox sore for infecting the teenage boys compared to any other body fluid such as saliva. What happened when the boys were injected with the cowpox sore in terms of the ability of the smallpox to affect the boys. Be sure to use words such as antigen, antibodies, and memory cells. Describe how genes change in order to produce new antibodies for a new infection. Find another vaccine which is produced by infecting someone with a mild disease whose virus is similar to a deadly disease.
Prince Morkeh (pmorkeh4@student.d125.org)
A vaccination is a less harmful exposure to a disease in order to prevent full on, and often deadly symptoms. It stimulates the immune system to remember the disease and later fight against it. In the case of Dr. Jenner and the Small pox vaccine, he used the red lesions or sores to scrape because they carried higher counts of the virus. Often times though, these sores would rupture and fill saliva with high amounts of the cowpox virus as well. Cowpox is a less harmful disease than smallpox; it was often passed on to “milkmaids” through “cow udders” (Moalem 125). Once exposed though, the person would become immune to smallpox, which henceforth led to his discovery of vaccine-induced immunity.
ReplyDeleteAccording to an article published in “PubMed,” smallpox and cowpox releases antigens in the bloodstream for the “extracellular enveloped virus” which is then categorized as a non-self antigen or an invader to the human body. Then, the body releases antibodies “specifically tailored” to the cowpox virus, in a sort of lock and key interaction, which kills the antigen (126). As learned in class, the antibody cells or the plasma cells secrete memory cells that survive in the body for years. In the case of cowpox, the memory cells create antibodies for both cowpox and smallpox, thus preventing a later infection. In biological systems, as mentioned in main idea number 3 often times living organisms respond to information involved in life processes. Genes respond to antigens in a similar way. Class switching occurs after the maturing of a B memory cell, which helps create different classes of antibodies; hence why cowpox leads to smallpox immunity and how “genes could change” (126).
The flu shot is a similar vaccine to that of small pox. The injection exposes people to 3 or 4 different types of influenza antigens in order to create antibodies for them. That is why often times people who have just received the flu shot feel minor flu-like symptoms. Though the flu is not deadly most of the time, it can be!
Madeline Merageas (mmerage4@students.d125.org)
A vaccination is the injection of a relatively harmless version of a potentially very harmful virus. The injected version is either weak or killed and split into fragments, so rather than growing to become life-threatening, the virus will be attacked by antibodies and killed off. When the boys were injected with the cowpox sore, the cowpox virus entered their bodies as a pathogen with a non-self antigen, or a foreign substance that stimulates a specific immune response. This antigen generates antibodies to dock to the antigen to makes it easier for macrophages to find and harder for pathogens to effectively infect the boys. Since the virus was injected, the humoral response and cell-mediated response occur as the virus has already gotten past the body’s first and second lines of defense. The humoral response begins with the antigen triggering B lymphocytes to produce antibodies specific to the antigen. Memory B cells are also produced to ensure immunity against the antigen for the rest of the boys’ life (and more importantly, also to the smallpox virus). The cell-mediated response is the killing of cells in the body that are already infected with cowpox. In this response, killer T cells dock next to infected cells and kill them. Memory T cells are also produced. When the boys are exposed to the smallpox virus, their immune system will then already recognize it and be able to react with a secondary immune response in which memory B and T cells can readily make antibodies to combat infected cells.
ReplyDeleteDr. Jenner probably used a scrape of a cowpox sore because it was an infected fluid that, when injected, would stimulate the humoral response in the recipient. Saliva is part of our bodies’ 2nd defense-- the nonspecific internal defense-- and might not stimulate the humoral response in the immune system that would be able to later respond to the smallpox virus. Additionally, I agree with Madeline that the sores of the cowpox virus contain higher counts of the virus than saliva.
According to Discovery Medicine, genetic immunization has recently become more widely used. It involves the customizing and manufacturing of DNA sequences to code for proteins that produce antibodies and is much more cost-effective with better specificity than previous genetic immunization techniques. This relatively new technology is one way genes are manipulated to create antibodies for new infections and is related to Big Idea 3: Living systems store, retrieve, transmit, and respond to information essential to life processes. The animals that benefit from specific antibody-producing proteins are using the essential genetic information from DNA sequences to fight new infections.
(http://www.discoverymedicine.com/Ross-S-Chambers/2009/05/24/antibody-production-using-genetic-immunization/)
Another example of a mild strain of a disease that protects from a deadly disease is the vaccination for tuberculosis, BCG. BCG, Bacille Calmette Guerin, contains a live, but weakened, strain of Mycobacterium bovis originally from cows with tuberculosis. Now several strains of BCG exist throughout the world to protect against tuberculosis.
(http://www.who.int/vaccine_research/diseases/tb/vaccine_development/bcg/en/)
Stephanie Li (steli4@students.d125.org)
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ReplyDeleteA vaccination is a prepared substance that contains a less harmful version of an otherwise harmful virus. A vaccine is injected into a patient to stimulate a specific immune response. The reason why a patient is not sickened by this is because the virus is, “weakened or killed and broken up into pieces or a relative close enough to the harmful virus that our bodies will recognize it, but distance enough that it doesn’t cause serious disease” (Moalem 126). In Edward Jenner’s case, the boys were injected with a cowpox virus from a cowpox sore. I agree with Stephanie that this generated a specific immune response since the pathogen got past the first and second line of defense due to the nature of the injection. Macrophages recognize the cowpox pathogens as foreign substances, and they engulf the pathogens. These macrophages break down the pathogen, but at the same time, they present the antigen, or identification, of the pathogen on the cell surface. This MHC then corresponds with helper T cells, a type of lymphocyte or specific white blood cell. Helper T cells recognize the antigen and cytokines, a chemical signal, is released to activate killer T cells or B cells. The humoral and cell-mediated, both specific immune responses, then follow. The humoral response is intiated as helper T cells release cytokines to cause proliferation of B cells. Some of these B cells become plasma B cells, which act as antibody producing factories. These antibodies mark the pathogen for destruction by macrophages or other lymphocytes, and these antibodies have a specific shape for a specific pathogen. Other B cells will become memory B cells which ensure an immunity (secondary immune response) against that specific pathogen, in this case cow pox. Memory B cells allow for a quicker response and antibody production if cow pox was to enter the body again. Since cow pox is similar to small pox, these memory B cells also provide a degree of immunity to small pox. Similarly, helper T cells can also release cytokines to activate killer T cells. The cell mediated response is then initiated as is utilized when normal cells are already infected. As a pathogen infects a cell, the cell presents the antigen on its surface for recognition. Activated killer T cells recognize the antigen and release perforin to cause the infected cell to lyse. At the same time, memory T cells can be created to ensure a secondary immune response if infected by the same pathogen again.
ReplyDeleteI agree with the previous comment that Dr. Jenner probably used a scrape sample directly from a cowpox sore, because it probably had higher accounts of the virus. Although it is true that saliva is a second line of defense (nonspecific internal defense), Stephanie did not mention specifically why saliva wasn’t beneficial when trying to obtain a high concentration sample of the cow pox virus. Saliva has lysozymes and other chemicals that trap and kill harmful bacteria. At the same time, mucus can also play an important role. Mucus traps bacteria and inhibits its spread and growth. Cilia comes and washes away the mucus, bacteria and all, until it is coughed or sneezed out. Saliva would not be a beneficial source to try to obtain a high concentration of the cowpox virus because of its many bacterial fighting agents. The cowpox sore, on the other hand, has already been infected and has a clear and present virus concentration. This relates to Big Idea 3: Living systems store, retrieve, transmit, and respond to information essential to life processes, because this non specific defense system is essential in eliminating pathogens.
ReplyDeleteSince each specific infection requires specific antibodies, genes are always being regulated and activated in order to produce those specific antibodies when the body is exposed to new and foreign diseases. At the same time, pathogens are always evolving to combat the specific immune response. By using antibodies and other forms of treatment to fight off pathogens, medicine has forced an “antibody arms race” with pathogens. Over time, these pathogens evolve and are able to develop a new strain that is resistant to that specific antibiotic. One example of another vaccine would be the hepatitis B vaccine. There are five recombinant hepatitis B vaccines approved by the FDA: Engerix-B; Recombivax HB; Twinrix; Comvax; and Pediarix. The recombinant hepatitis B vaccine is created through genetic engineering of DNA by inserting a segment of the viral gene in a yeast cell. This creates a weakened strain, but it still triggers an immune response to create memory cells for that pathogen.
http://www.nvic.org/vaccines-and-diseases/Hepatitis-B.aspx
Weilly Tong (wtong4@students.d125.org)
Vaccine is the substance that will stimulate specific immune response and ultimately the production of memory cells that have the antigen of the injected vaccine. This is to prepare for the future infection of such disease, and vaccine usually used a dead strain of pathogen or the weaker version of pathogen; in the case of Dr. Jenner, cowpox served as the weaker strain of smallpox virus and since they have very similar antigens, the antigen acquired from cowpox can evoke immune response to the smallpox virus and allow body to store its information using memory cells (memory T and B cells). The vague representation of this process is defined in 126 of the book Survival of the Sickest.
ReplyDeleteThis is known as the artificial active immunity since production of antibody for such antigen is undergone and the body will store that information in the memory cells. Dr. Jenner scrape a bodily fluid of cow that contain cowpox to the sore of boys to put virus directly into the body and allow it to circulate around the body through bloodstream. The another example of vaccine that uses the weaker version of pathogen as the substitute for actual pathogen, along with hepatitis B vaccine suggested by Weilly and BCG suggested by Stephanie, is the Measles vaccine; measles is the deadly disease which is highly contagious disease. In many countries, Measles is almost extinct, but in some countries such as Japan still have many cases of Measles infections. Because of Measles vaccine, almost 99% of the infection has been prevented according to CDC (Centers for Disease Control and Prevention). Most of the time, the vaccine for measles is given with combination of other vaccines, and it is recommended to be taken periodically in young age. (http://www.cdc.gov/measles/vaccination.html). This is related to the concept 3 about the response of organisms to the outside stimuli since the immunity os one of the response to the foreign organisms invading to the body.
Makoto Seita (e-mail: mseita3@students.d125.org)