Precipitation TEST WORD PDF

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VETERINARY IMMUNOLOGY DVM 3RD SEMESTER

FARHAN QURESHI

PRECIPITATION TEST: 

It is a rapid, inexpensive & reliable test.

MATERIALS REQUIRED: For every test, we require    

Vehicle (petri dish, test tube, slide) Reaction mixture (PBS or Normal saline) Reactants (antigen, antibody) Markers/Identifiers (enzymes, dyes)

PROTOCOL: i. ii. iii. iv. v. vi.

Take a slide Put a drop of Rose Bengal Agent Add one drop of sera/whey/milk Mix with sterile wooden stick Wait for some time (2-3 minutes) After some time visible precipitates will be formed

OBSERVATIONS: 

White precipitates will be formed with pink surroundings

RESULT:  

If precipitates are formed, result of the test is +ve If precipitates are not formed, result of the test is –ve

INFERENCE: Animal is Brucella abortus +ve

LOGIC: Rose Bengal is a dye pink in color. Brucella abortus is taken, cultured, digested, some protein antigens are left behind. We covalently bind them & it becomes a pink solution. Take 3-5 ml of blood without anticoagulant. Keep the tube at 45º angle, serum will get separated at top above the blood.Try that serum should not be pink in color. When you mix, reaction takes place between antigens in RBS & antibodies in serum. Antigenantibody complex will be shown as precipitates.

 Precipitation test is a screening test which is inexpensive, rapid (within 5 minutes), efficient but not 100% accurate.

AGAR GEL PRECIPITATION TEST: PROTOCOL: i. ii. iii.

iv. v. vi.

Take noble agar in 90mm plate. If noble agar is not available, take nutrient agar. Make a hole of 3mm size. Make another hole of 3mm size 4mm away from the first hole. Similarly make 3 or 5 or 7 holes. In case of 5 holes, central hole is the deciding hole, it will have antigens or antibodies (known thing). Out of remaining 4 holes, 3 holes will contain flock sera while one hole will act as a control (known antisera is present) Each well is filled to full. Incubate at 25-30℃ for 48 hours. It should be placed in humid chamber. Read after 24 hours & then 48 hours.

OBSERVATIONS: 

Spur will be formed where antigen & antibody react.

RESULT:  

If spur is formed test is +ve If spur is not formed test is –ve.

LOGIC:  

Antigen-antibody reaction Specificity...