IMMUNOLOGIC AND MOLECULAR DIAGNOSTICS Flashcards
The entry, invasion and multiplication of disease causing organisms (pathogens) in a host’s body in which usually prompts an immune response.
Infection
Is the process/practice of determining the nature of a disease or disorder
Diagnostics
How is an infection diagnosed?
- Physical examination to check for signs and symptoms
- Detect the presence pathogen/causative agent via tests/assays/culture methods (direct)
- Detect the immunologic reaction of our body due to the presence of the pathogen/causative agent (indirect)
- deals with the response of an organism to antigenic (foreign bodies) challenge
- its recognition of what is self and what is not.
- properties of the organism that help it to combat itssusceptibility to foreign organisms, material, etc.
Immunology
The adaptive immunity relies on the specific interaction of
antigens and antibodies
specific portions/parts of the pathogen that could elicit an immunologic response.
Antigen/Immunogen
In response to the presence of antigens our bodies will make _________ that neutralizes these antigens
antibodies
Y-shaped glycoproteins produced by B-cells that identify and neutralize pathogens
Antibodies or Immunoglobulins
How does our immune system “remember”?
● Specific antibodies are created by B-cells in response to a specific antigen.
● During our first encounter with the antigen our bodies prompts a response via antibody production but can be slow.
● On our next encounter with the same antigen, the same antibodies will respond so symptoms are significantly reduced.
ELISA acronym meaning
Enzyme-linked immunosorbent assay
● Diagnostic examination of blood serum with
regards to the immune response.
Serology
is blood plasma without the clotting factors
such as fibrinogen
Typically obtained via centrifugation of the blood plasma and used for diagnostic purposes
Serum
- An indirect detection of the pathogen
- Can detect past infection because antibodies can be present even after infection subsides (post infection)
Antibody Detection
can create false positives due to the detection of antibodies present in the body
Antibody Detection
- A form of direct detection of the pathogen
- Conducted on the onset of symptoms
- Better in detecting on-going infection
Antigen Detection
________ levels in the body decreases after the infection subsides
Antigen
Most HIV rapid self test kits (lateral flow) used within the 23-90 day period after exposure are
antibody tests
detects delayed-type hypersensitivity response mediated by T lymphocytes and, in patients with prior mycobacterial exposure
Tuberculin test
Secreted into mucous, saliva, tears,colostrum. Tags pathogens for destruction.
IgA
B-cell receptor. Stimulates release of IgM.
IgD
Binds to mast cells and basophils. Allergy and antiparasitic activity.For allerggies and antihistamine
IgE
Binds to phagocytes. Main blood antibody for secondary responses. Crosses placenta. stays after the first infection
IgG
Fixes complement. Main antibody of primary responses. B-cell receptor. Immune system memory, used for the first encounter of the virus. indicative of newly getting infected with the virus
IgM
Antibodies bind to and inactivate viruses and toxins. These antibodies are called
neutralizing antibodies
immune process where Antibodies recognize, bind to and inactivate viruses and toxins.
neutralization
an immune process that helps the body identify and destroy pathogens and old cells. It involves coating pathogens with opsonins, which are specific serum proteins, to help phagocytes recognize and engulf them.
Opsonization
Opsonization process
immune process where antigen-antibody complexes activate the complement system (the classical pathway), triggering its antibacterial activity.
Phagocytic cells grab the antibodies bound to the surface of foreign substances, for efficient phagocytosis.
Techniques for Antibody/Antigen Detection:
the binding of antigen and antibody is indicated by a colorimetric reaction of an enzyme and substrate in a microplate.
ELISA
in ELISA, The intensity of color can be measured via ____________ w/c is correlated to the titers of antigen or antibody present in the sample
spectrophotometry
ELISA types
Direct, Indirect, Sandwich, Competitive ELISA
ELISA types:
Detects the presence of antigen, uses only the pirmary antbody conjugate
direct elisa
ELISA types:
Detects the presence of antigen, uses only the pirmary antbody conjugate. a two-step ELISA which involves two binding process of primary antibody and labeled secondary antibody. The primary antibody is incubated with the antigen followed by the incubation with the secondary antibody.
Detects the presence of he antibody
indirect elisa
ELISA types:
the well is coated with capture antibody along with sample antigen, then 2 antibodies willl connect in top of it with the enzyme that allows a colometric reaction
detects the antigen
sandwich elisa
ELISA types:
helps to detect antigen concentration in a sample. sample with antigens are coatd in the wells, then the inhibitor antigen and antigen of intrest fight to attach to the sample. inhibitor antigen allows colorimetric reaction
decreases in color when positive for antigens, and prevents false positives
competitive elisa
Techniques for Antibody/Antigen Detection:
● Filter paper-based platform
● Detection is expressed qualitatively (+) or (-).
● Work based on affinity chromatography (relies on specific biochemical interaction e.g. antigen-antibody).
● A color reaction is observed when the target analyte reacts with biomolecule in the test.
Lateral Flow Assay
Techniques for Antibody/Antigen Detection:
formation of clumps (blood or latex beads) due to presence of an antigen or antibody.
Agglutination test
Agglutination test mechanism
latex beads with antigen yield the presence of antibodies
latex beads with antibodies yield the presence of antigen
detection of a protein antigen immobilized on the protein-retaining membrane support
The detection of the protein of interest relies on the binding of an antibody that specifically recognizes the protein of interest exposed on the membrane
This uses two sets of antibodies (primary and secondary)
allows the detection of several targets
Immunoblot or Western blot
Immunoblot or Western blot membrane suppport material
such as nitrocellulose or polyvinylidene fluoride (PVDF).
main difference between traditional diagnosis of infection methods vs molecular methods
traditional methods still need AST to determmine resistance vs molcular methods that are considered to determine whether the infectious disease is resistant using nucleic acid and proteins
two major parts of the immune system
adaptive vs innate immune system
two major parts of the immune system:
rapid
broad target
no memory
no specific target
innate immune system
innate immune system example that serve as physical barriers
skin, mucosal layer of organs
innate immune system example that serve as chemical barriers
stomach acid, lysozome in eye
two major parts of the immune system:
cell-mediated response, humorla response
first infection response does not ellicit a response, but the infection has a response due to memory of the cell
has memory
specific
slow
adaptive immune system
example of pathogens with serial codes
H1N1 or E. coli O157:H7
Important strains of pathogens are usually designated with a _______
represent _________ for antigen
serial code
in a lateral assay flow result, IgM is inidicative of
early infection stage
in a lateral assay flow result, IgG is inidicative of
post infection stage
in a lateral assay flow result, IgM/IgG is inidicative of
Late infection stage
