Defense Against Infectious Diseases Test Flashcards
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Identifying Blood Types
-Anti-A antibodies bind to A proteins (if causes “clumping” in a blood sample, shows that A proteins ARE PRESENT)
-Anti-B antibodies bind to B proteins (if causes “clumping” in a blood sample, shows that B proteins ARE PRESENT)
-Anti-D antibodies bind to Rh proteins (if causes “clumping” in a blood sample, shows that Rh proteins
ARE PRESENT)
-Note: no clumping = that protein is NOT present
HIV
-Surface proteins on HIV are highly specific, as are all viral proteins, and can ONLY interact with SPECIFIC proteins on SPECIFIC cells in the body to infect them.
-The cells that HIV infects are T-lymphocytes (CD4+).
Helper-T cells, remember, activate B cells to produce antibodies to “tag” infections in the body and to create memory B cells to protect a person from secondary infections
-When HIV infects helper-T cells it becomes “latent”/ dormant (symptoms of the disease do not show up for a long period of time after the infection)
-When HIV becomes active, helper-T cells begin to die off, causing B cells to remain inactivated during infection (no antibodies and no memory cells)
-This causes the symptoms of AIDS to develop (final stages of the infection), as a person is no longer able to fight off pathogens the same way they did before. Because of this, secondary infections usually kill individuals with AIDS, as they have no long-term immunity anymore.
-HIV is transmitted through the exchange of bodily fluids (unprotected sex (latex condoms provide barrier to HIV), blood-to-blood contact – needle sharing, breastfeeding, childbirth etc.)
-HIV RNA injected into helper-T cells, copied into DNA (reverse transcriptase), incorporated into helper-T cell DNA.
-Helper-T cells divide, spreading the infection – eventually results in symptoms of AIDS due to lowered numbers of healthy helper-T cells
-Small number of people are immune to HIV infection (they do not have the CD4+ protein receptor on their helper-T cells, so the virus has no way to get in)
Monoclonal Antibodies and Treatments
-Used in injections given to patients who have been bitten by rabid or venomous animals
-Used in cancer treatments: Cancer cells produce cancer-cell-specific antigens. Monoclonal antibodies to these antigens can be produced in a lab and attached to toxins or radioisotopes.
-When they are injected into cancer patients, the toxins will target the cancer cells, or the radioisotopes will identify exact locations of cancer cells for pin-point radiation therapy
Monoclonal Antibodies and Pregnancy Tests
-Monoclonal antibodies to HCG (human chorionic gonadotropin) are produced in a lab. HCG is ONLY produced by an embryo, so only a pregnant woman will have HCG in her bloodstream (and urine).
-In a pregnancy test, HCG antibodies are attached to a color-changing enzyme and these are placed in a well (or on a test strip etc.).
-IF HCG is present in a woman’s urine, a color change will occur when the HCG antibodies bind with the HCG antigens present in her urine!
Monoclonal Antibodies and Disease Detection
ELISA wells are coated with antigens from a specific pathogen and a color-changing enzyme. A sample of the patient’s blood is placed in the wells. If a color change occurs, their body is producing the antibody to that specific antigen – showing that they have the infection (malaria/ HIV etc.)
Monoclonal Antibodies Production
-A particular antigen is injected into a lab animal
-A primary immune response is allowed to occur in the animal (polyclonal)
-The animal’s spleen is harvested (blood cells collected)
-Lymphocytes (B cells) are identified/ isolated and removed and grown with cancerous cells (myelomas – divide forever)
-SOME of the B cells (which produce antibodies) and myelomas fuse as they are growing together, creating cells called hybridomas
Individual hybridomas are identified and grown in their own SEPARATE containers
-An ELISA (enzyme-linked immunosorbent assay) test is used to identify which hybridoma cultures are producing the ONE desired antibody
-The cells in these cultures continue to divide (mitosis) and produce a large amount of the ONE (monoclonal) desired antibody (which can be purified and used to treat or diagnose patients)
Monoclonal Antibodies Overview
Monoclonal (mono = one, clonal = copy): all of the antibodies that are produced are the exact SAME (typically, this is done in a lab – NOT in the body!)
Understand that monoclonal antibodies are produced by hybridoma cells and that fusion of a tumor cell with an antibody-producing plasma cell creates a hybridoma cell.
Monoclonal antibodies are produced in labs for treatments (such as a rabies shot, antivenom, to treat Covid-19 etc.) or diagnoses (such as a pregnancy test)
Vaccines
Understand that vaccines contain antigens that trigger immunity but do not cause the disease (trigger active immunity).
-Vaccines are developed by “weakening” a pathogen (heating it, chemical treatments (attenuation)), or selection of a weak strain and injecting it (or its parts) into the body to purposefully trigger a primary immune response (to develop memory B cells without actually having to contract the full blown infection itself)
-The body recognizes the weakened pathogen as “non-self” and begins the process of a primary immune response, which will eventually result in memory B cell formation (long-term immunity)
-Memory cells begin producing antibodies to the pathogen RIGHT away upon subsequent exposures, causing a quicker, more effective response (you may not even have symptoms of the infection!)
-Vaccines do NOT prevent infection by the pathogen, but rather provide the body with its own memory cells to cause a faster, more intense response to the pathogen should it be encountered again
Immunity
The ability to resist infection is either innate (genetic – you are born with it) or acquired (you develop it over time)
Acquired immunity is either active or passive, and both active and passive immunity can be conferred to an individual through natural means or artificial means
Active Immunity
The immune system is “challenged” by an antigen (naturally or artificially), responds, and produces memory cells, leading to long-term immunity (an individual organism produces its own antibodies)
Passive Immunity Overview
One organism receives antibodies from another organism/ source. This confers SHORT-term benefit only (antibodies target antigens and pathogens are destroyed). NO memory cells are produced in the organism who receives the antibodies though (no long-term immunity)
Passive Immunity Examples
-Antibodies from mother to fetus (placenta)
-Antibodies from mother to baby (colostrum – first milk production after a baby is born)
-Injections of antibodies (when bitten by snakes, spiders etc.) to prevent massive tissue damage/ death (as a primary immune response in these instances would take too long)
B-Cell Cloning
produces TWO types of cells:
1. Antibody-secreting plasma cells: make and secrete antibodies (~2000 secreted into the bloodstream every second) immediately to “target” the (primary) infection for destruction
2. Memory cells: long-lived cells which do not secrete antibodies initially. Instead, they remain in the bloodstream and will secrete antibodies if a subsequent (secondary) infection occurs (providing your body with immunity from the same pathogen should it invade again)
Steps of Antibody Production in the Body
-In a PRIMARY INFECTION : Macrophages identify “non-self” antigens and engulf/ ingest pathogens
-Antigens (or pieces of them) from the pathogen remain in the macrophage and are “displayed” on the macrophage cell membrane to WBC’s called helper-T cells (TH cells) which “activates” the TH cells
-Helper-T cells release cytokines to activate specific B cells (lymphocytes – produced in bone marrow – millions of different types) in the body that are able to produce the specific antibody that is needed for that specific pathogen
-Because B cells exist in VERY small numbers in the bloodstream, once they are activated, B cells begin to divide rapidly (mitosis – exact copies) so that there are enough of them to produce the proper antibody in large enough amounts to be effective – this is called B cell cloning