Written Exam 3 Slide groups 1-3 Flashcards
What is immunodiagnosis?
Using antibody-antigen interactions to identify pathogens and diagnose infection
What is an in vitro diagnostic test of serum
Serological test

What is plasma with all clotting factors removed; the blood fraction that contains antibodies?
Serum

How are serological tests used to identify antibodies in sample?
- Patients serum antibody content unknown is taken and placed on a slide
- A prepared known antigen is added to the serum
- A positive Ab-Agn interaction is usually evident as some visible sign, such as a color change or clumping

How are serological tests used to identify antigen in a sample?
- Isolated colony identify unknown from an agar plate and then placed on a slide
- Antibodies of known identity added to the slide with the unknown colony
- A positive Ab-Agn interaction is usually evident as some visible sign, such as a color change or clumping

Explain the Latex agglutination test
Pathogen-specific antibody cross-links antigen-coated latex particles, forming complexes that settle out and form visible clumps
**When more concentrated serum is added, there are more agglutinated particles since the antigen-coated particles are bound to the antibody -> creating a clump

Explain Hemagglutination Inhibition Test
- Uses red blood cells (RBC) as indicators instead of latex particles
- Some viruses bind to antigen on RBCs and agglutinate RBCs
- Mumps, measles, influenza
- Antibodies to the virus will block the virus’ ability to agglutinate RBCs
- Inhibition of agglutination indicates the presence of antibodies to the virus

Explain Labeled Antibody Tests and list examples
Uses antibody molecules that are linked to some molecular “label” that enables them to be easily detected
- Used to detect either antigens or antibodies
Examples:
- Fluorescent antibody tests (immunofluorescence)
- ELIZA
- Western blot to detect proteins
Explain Immunofluorescence and describe the steps
- Antigen is attached to slide and flooded with patient’s serum (serum includes IgG from patient)
- Fluorescent-labeled anti-IgG antiglobulin is added
- Fluorescent label is attached to the anti-IgG (antiglobulin)
- Allowing it to fluoresce
- Fluorescent label is attached to the anti-IgG (antiglobulin)

What does ELISA stand for?
Enzyme Linked Immunosorbent Assay
Explain the process of ELISA
- A patient’s _antibodies bind to known antigen_ that is attached to a well in 96 well plate
- Patients antibodies are detected by a secondary antibody that is labeled with an enzyme
- When substrate is added, the enzyme-antibody complex hydrolyzes the substrate, which releases a dye
- Wells that develop color are positive for the antibody; colorless wells are negative

Explain how ELISA is used to detect an antigen
- Specimen is coated with antibodies, NOT ANTIGEN
- Antigen washed over the sample and antigen binds to the antibodies
- Secondary antiviral antibody binds and the Antiimmunoglobuilin enzyme is then added and bound to the second antiviral antibody
- Enzyme-antibody complex hydrolyzes the substrate and releases a die.

When using ELISA, what is used to detect HIV?
p24 Antigen (colored wells indicate reactivity)
Explain Western blots and how the work
- Used to identify presence of antigen
- Run gel electrophoresis on proteins isolated from a clinical sample
- Transfer proteins to a nitrocellulose membrane
- Incubate membrane with primary antibody
- Primary antibody binds to its antigen protein
- Add secondary antibody that is labeled with an enzyme
- Visualize the protein

Explain Immunochromatography tests and how they work
**Rapid diagnostic tests
- Prepared antigen extracted from patient (in beaker)
- Movement of fluid containing complexes of antibodies bound to antigen
- Anti-antibodies stop movement of antibody-antigen complexes. Color becomes visible because of density of complexes

What is a major example (common) of immunochromatography tests?
Pregnancy tests (at home method) = Rapid diagnostic tests

Explain the relationship between Normal Microbiota and the Host
- Microbiota (aka normal flora): The microorganisms that normally colonize various sites on/within the body without causing disease
What is the difference between resident and transient microbiota?
- Resident Microbiota = inhabit sites for extended periods
- Transient microbiota = inhabit temporarily
What is the ability of a microbe to stay affixed to a body surface and replicate? and how is this achieved?
Colonization
Achieved by:
- Adhesins
- Environmental factors
- susceptibility to pathogens
Where do the normal microbiota colonize in the host?
- Conjunctiva, Nasal mucosa, Oral mucosa, Pharynx, Skin, Large intestine (colon), Rectum, Urethra, Vagina

What spots in the body are normally free of microbes (sterile)?
Blood, CSF and internal organs
What does our microbiota do?
- Part of our first line of defense against infection – competitively exclude pathogens
- Covering of blinding sites prevents attachment
- Consumption of available nutrients
- Production of compounds toxic to other bacteria
- Aid in digestion, in vitamin production, drug metabolism
- Many other functions that are just now learning about (the Human microbiome project)
How do we acquire the microbes that make up our normal microbiota?
- From mother to baby
- Oral (pre-mastication of food)
- Mammary, through breastfeeding (selection)
- Cutaneous (contact with skin)
- Vaginal (passage through birth canal)
- Mom’s oral hygiene is important as it influences the baby oral microbiota

What can perturb the normal microbiome of a person?
- By age three, a child’s microbiome looks a lot like an adult’s, and it becomes much more stable
- It continues to change in response to events like illness, disease, antibiotic treatment, fever, stress, injury, and changes in diet
























