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7/26/2019 Serologi-1

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Precipitation tests

Agar immunodiffusion

Lab 5


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Serological Tests

Precipitation tests

Antigen/Ab conjugation

Neutralisation tests Agglutination tests

ELISA tests

Complement Fiation !ests "CF#


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Precipitation tests

%ne of t&e properties of some antibod'

classes is t&e abilit' to precipitate from

solution (&en combined (it& multi)alent

antigens* suc& reactions can be )isuali+ed

!&is be&a)ior is called precipitation


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Agglutination tests

Antibodies can agglutinate multi)alent

particulate antigens- suc& as red blood

cells or bacteria

!&is be&a)ior is called agglutination.

Serological tests based on agglutination

are usuall' more sensiti)e t&an t&ose

based on precipitation


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Neutralisation tests

suall' used for )iral or bacterial/toin

identification

Antibod' neutralises t&e toin andpre)ents its action "antitoins#

0e1uires an indicator s'stem e.g. lab animals-

tissue culture- etc


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Antigen/Ab conjugation

Antigens "or immunoglobulins# can beconjugated (it& ot&er molecules"radioisotopes- en+'mes or fluorescent

d'es# so t&at antigen3antibod' binding canbe detected at etremel' lo(concentrations.

Eamples are radioimmunoassa' oren+'me3immunoassa'- Fluorescentantibod' tests "FA!#.


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Guide to the use of Serological Tests

&ic& test6

Consider 7

t&e organism

t&e most accurate test "sensiti)it'/specificit'# 1uantitati)e )s 1ualitati)e

t&e legal status of t&e test

t&e material "sample# submitted


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Precipitation Tests

sed for soluble antigen &en soluble antigen reacts (it& its specific

antibod' in solution- t&e antigen3antibod'

comple ma' become insoluble and precipitate

0elati)el' less sensiti)e

Eamples 0ing precipitation test

Lancefield grouping

Agar gel immunodiffusion "A9I:#

%ptimal proportions of antigen andantibod' causes precipitation

Ecess antibod' or antigen ; noprecipitation


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Ring precipitation test


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Lancefield grouping


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Agar gel in plates or on microscope slides

?a@e (ells in agar for bot& antigen and

antibod'

!(o reactants diffuse into agar and form

immunoprecipitates (&ere optimal

proportions occur

Agar Gel Immunodiffusion


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Reaction of identity


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Reaction of partial identity


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Reaction of nonidentity


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Radial Immunodiffusion

Antiserum Antigen

Decreasing AntigenConcentration


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LogAg

conc.

Diameter of the precipitation ring

Prepare a standard curve

Allows exact quantification of antigen

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