Summary BoD (Biology of Disease, Pathology) Practical Notes

BoD (Pathology) Practical Notes
Michaelmas
Agglutination
● Complete precipitation will only occur at an optimal ratio of antibody
and antigen. This ratio defines the volume of undiluted antibody which
is equivalent with one volume of undiluted antigen of known
concentration
● There is neither antibody nor antigen left in solution after removing the
precipitate.
● Coombs test
○ Many of the antibodies to Rhesus antigens e.g., anti-Rh D, are

non-agglutinating
○ Need additional anti antibody antibody


LFT
● Sandwich
○ Conjugate pad
◆ Has antibody that binds antigen
○ Test line
◆ Has antibody that binds antigen
○ Control line
◆ Has antibody that binds antibody
○ Process
◆ So test line shows positive result
● Antigen inhibition
○ Conjugate pad
◆ Has antibody that binds antigen
○ Test line
◆ Immobilised antigen
○ Control line
◆ Has antibody that binds antibody
○ Process
◆ If antigen is present in sample, conjugate pad mAbs will be

saturated and won’t bind at test line
◆ So test line shows negative result


Bacteria need to be in logarithmic growth phase for virus to replicate