Week 6 - Immunoassays Flashcards
Purpose of Staphaurex test
Differentiate between Staph that possesses coagulase or Protein A
Indirect Agglutination - need bead for visibilty
Reagent - IgG and Fibrinogen
Bound coagulase - slide test
Free coagulase - tube test
Staphaurex POS and NEG control
POS - S. aureus
NEG - S. epidermidis
Direct Agglutination
Ag is naturally present on cell surface
ABO, Rh, Lancefield (Strep)
Indirect Agglutination
Particulate is coated with foreign Ag or Ab
RBC, latex bead
Hemagglutination
RBC agglutination
Med-Strep Testing
Identification of Streptococci on Lancefield groups A, B, C, D, F, G CARBOHYDRATE GROUPS
Latex particles are coated in rabbit Ab
Direct
What is an Immunoassay
Tests for the binding of Ab to their specific targets (complementary Ag)
Heterogenous Immunoassay
Physical separation step of Ab-bound Ag from remaining free Ag
Homogenous Immunoassay
Does not involve physical separation of Ab-bound Ag from Ag molecules that remain free
Competitive Immunoassay
Reactants are added together at the same time
Labelled Ag competes with unlabelled Ag for binding site
Non-competitive Immunoassay
sandwich assay
Pregnancy Test
Immobilized Ab
Control - sideways bound between immobilized Ab and gold complex Ab
Sandwich
Analyte between 2 Ab
Direct
Label Ag and unlabelled Ag
Inversely Proportional
Doesn’t use secondary Ab
Indirect Immunoassay
Ag - Ab - Ab
Secondary Ab, antigen specific
