Agglutination immunoassay and kit for determination of a multivalent immune species using a buffered salt wash solution

Claim 1

An agglutination method for the determination of a multivalent immune species comprising: (a) contacting an aqueous liquid containing said species in free form with a reagent comprising water-insoluble particles having tracer molecules associated therewith and receptor molecules reactive with said species bound to a surface thereof, so as to form an agglutinate of a reaction product of said species and said receptor molecules, (b) simultaneously or subsequent to said contacting step (a), contacting said agglutinate with a microporous water-insoluble membrane having an average pore size which is at least 5 times greater than the average diameter of said water-insoluble particles, (c) washing unagglutinated residual materials through said membrane while leaving said agglutinate thereon, said washing accomplished with a wash solution having a pH of from about 5 to about 10 and an ionic strength of at least about 0.25, and (d) determining the amount of tracer molecules either in said agglutinate remaining on said membrane or said residual materials.

Claim 19

A method for detecting Streptococcus A comprising: (i) providing an applicator including an applicator stick and a fibrous swab and collecting a biological sample with said swab, (ii) providing an extraction composition comprising sodium nitrite and citric acid for effecting release of Streptococcus A antigen from said swab, dipping said swab in said extraction composition and incubating said swab within said extraction composition for a period of time sufficient to release antigen from said swab, (iii) neutralizing the solution of said extracted antigen, (iv) contacting said neutralized solution of said extracted antigen with an agglutination indicator reagent comprising water-insoluble, polymeric core-shell latex particles having an average diameter of from about 0.1 to about 0.7 micrometer, and having molecules of a colorimetric dye distributed substantially in particle cores and comprising antibodies reactive with said antigen bound to the surface thereof, so as to form an agglutinate of a reaction product of said antigen and said antibodies, said contacting being carried out in the presence of a microporous water-insoluble membrane mounted in a disposable test device, said membrane having an average pore size which is at least 5 times greater than an average diameter of said water-insoluble particles (v) washing unagglutinated residual materials through said membrane while leaving said agglutinate thereon, said washing accomplished with an aqueous wash solution having a pH of from about 6 to about 9 and an ionic strength of from about 0.5 to about 3, and (vi) determining the amount of colorimetric dye molecules in said agglutinate remaining on said membrane.

Claim 20

A method for detecting Streptococcus A comprising: (i) providing an applicator including an applicator stick and a fibrous swab and collecting a biological sample with said swab, (ii) providing an extraction composition comprising sodium nitrite and citric acid for effecting release of Streptococcus A antigen from said swab, dipping said swab in said extraction composition and incubating said swab within said extraction composition for a period of time sufficient to release antigen from said swab, (iii) neutralizing the solution of said extracted antigen, (iv) contacting said neutralized solution of said extracted antigen with an agglutination indicator reagent comprising water-insoluble, polymeric core-shell latex particles having an average diameter of from about 0.1 to about 0.7 micrometer, and having molecules of a colorimetric dye distributed substantially in particle cores and comprising antibodies reactive with said antigen bound to the surface thereof, so as to form an agglutinate of a reaction product of said antigen and said antibodies, said contacting being carried out in the presence of a microporous water-insoluble membrane mounted in a disposable test device, said membrane having an average pore size which is at least 5 times greater than an average diameter of said water-insoluble particles (v) washing unagglutinated residual materials through said membrane while leaving said agglutinate thereon, said washing accomplished with an aqueous wash solution having a pH of from about 6 to about 9 and an ionic strength of from about 0.5 to about 3, and (vi) determining the amount of colorimetric dye molecules in said agglutinate remaining on said membrane.