Methods of use of one step immunochromatographic device for streptococcus a antigen

Abstract

A method to determine the presence or absence of Streptococcus Group A antigen in a sample, comprising the following steps: extracting the antigen from the sample in an assay chamber with two or less extraction reagents, wherein the two reagents may be added to the assay chamber in no particular sequence; introducing a lateral flow immunochromatographic assay device into the extraction reagents containing the extracted antigen without further addition of reagents or manipulation of the sample; forming an antigen-indicator labeling reagent complex; and determining the presence or absence of the antigen in the sample by the presence or absence of a signal formed by the binding of the antigen-indicator labeling reagent complex to an indicator capture reagent specific for said antigen-indicator labeling reagent complex.

1 . A method to determine the presence or absence of Streptococcus Group A antigen in a sample, comprising the following steps: 
 (a) extracting the antigen from said sample in an assay chamber with one or more extraction reagents wherein the sample and one or more extraction reagents are in the assay chamber;    (b) introducing a lateral flow immunochromatographic assay device having a buffer thereon into said separate assay chamber in operative contact with the sample and one or more extraction buffers contained in said separate assay chamber and having said extraction reagents and said extracted antigen contact said buffer on said assay device to neutralize said extraction reagents;    (c) forming an antigen-indicator labeling reagent complex on said assay device; and    (d) determining the presence or absence of said antigen in the sample by the presence or absence of a signal formed by the binding of said antigen-indicator labeling reagent complex to an indicator capture reagent specific for said antigen-indicator labeling reagent complex on said assay device.    
     
     
         2 . The method of  claim 1  further comprising the step of: 
 (a) determining the presence of a positive control signal on said assay device.    
     
     
         3 . The method of  claim 1  wherein said sample is a throat swab and said extracting further comprises mixing said throat swab in said extraction reagents for at least 10 seconds in said assay chamber.  
     
     
         4 . The method of  claim 1  wherein said extraction reagents further comprise a sodium nitrite solution.  
     
     
         5 . The method of  claim 1  wherein the extraction reagents comprise a sodium nitrite solution having a concentration of 2M that is formed by mixing an acetic acid solution that has a concentration of 0.3 M, and a solution of 2M sodium nitrite, and wherein the color of the liquid changes from pink to light yellow as said 0.3 M acetic acid solution as said 2M sodium nitrite solution are combined.  
     
     
         6 . The method of  claim 1  wherein said lateral flow immunochromatographic assay device has a sample receiving region and a discrete analyte detection region.  
     
     
         7 . The method of  claim 1  wherein said lateral flow immunochromatographic assay device further comprises a test strip without a plastic housing.  
     
     
         8 . The method of  claim 1  wherein said lateral flow immunochromatographic assay device further comprises a test strip with a plastic housing.  
     
     
         9 . The method of  claim 1  wherein said assay device further has a sample receiving region thereon and said sample receiving region includes said buffer therein to neutralize the extraction reagents.  
     
     
         10 . The method of  claim 1  wherein said assay device further has a sample receiving region thereon and said sample receiving region includes a buffer, detergents and blocking agents therein.  
     
     
         11 . A method to determine the presence or absence of an antigen in a sample, comprising the following steps: 
 (a) extracting the antigen from said sample in an assay chamber with one or more extraction reagents,    (b) introducing a lateral flow immunochromatographic assay device having a buffer thereon into said separate tube-shaped assay chamber and having said extraction reagents and said extracted antigen in contact with said buffer to neutralize said extraction reagents following the insertion of said assay device in said assay chamber;    (c) forming an antigen-indicator labeling reagent complex on said assay device; and    (d) determining the presence or absence of said antigen in the sample by the presence or absence of a signal formed by the binding of said antigen-indicator labeling reagent complex to an indicator capture reagent specific for said antigen-indicator labeling reagent complex on said assay device.    
     
     
         12 . The method of  claim 11  wherein said extraction reagents cleave a carbohydrate antigen from a target analyte.  
     
     
         13 . The method of  claim 11  wherein said extraction reagents to disrupt cell walls or membranes to expose membrane bound analytes or intracellular analytes.  
     
     
         14 . The method of  claim 11  wherein said extraction reagents cleave a carbohydrate antigen from the cell wall of Group A  Streptococcus.    
     
     
         15 . The method of  claim 11  wherein said sample is a throat swab and said extraction reagents cleave an antigen from the cell wall of an analyte.  
     
     
         16 . The method of  claim 11  wherein said extraction reagents further comprise an acidic solution.  
     
     
         17 . The method of  claim 16  wherein said assay device further has a sample receiving region thereon and said sample receiving region includes a buffer therein to neutralize the extraction reagents.  
     
     
         18 . The method of  claim 11  wherein the extraction reagents comprise a sodium nitrite solution having a concentration of 2M that is formed by mixing an acetic acid solution that has a concentration of 0.3 M and a solution of 2M sodium nitrite, and wherein the color of the liquid changes from pink to light yellow as said 0.3 M acetic acid solution as said 2M sodium nitrite solution are combined.  
     
     
         19 . The method of  claim 11  wherein said lateral flow immunochromatographic assay device has a sample receiving region and a discrete analyte detection region and wherein the analyte detection region includes a discrete labeling reagent at a discrete labeling situs and an immobilized capture reagent at a discrete capture situs.  
     
     
         20 . The method of  claim 11  wherein said assay device is inserted into said separate assay chamber into contact with said extraction reagent and extracted antigen to allow said extracted reagent and extracted antigen to laterally flow along said assay device.  
     
     
         21 . The method of  claim 11  wherein said method can detect Group A Streptococcus cells when present at a concentration as low as 4×10 5  cells per sample.  
     
     
         22 . The method of  claim 11  wherein said assay device further has a sample receiving region thereon and said sample receiving region includes detergents and blocking agents therein to assist in the flow of the antigen-indicator labeling reagent complex.