N-acetyl-d-glucosamine for enhanced specificity of strep a immunoassay

Abstract

Methods, compositions and kits for detecting Group A streptococcus in a biological sample are described. More particularly, the present disclosure provides an immunoassay in which the specificity of detection of Group A streptococcus is enhanced by addition of N-acetyl-D-glucosamine. These methods, compositions and kits are useful in convenient, reliable and early diagnosis of streptococcal infection in a human subject.

What is claimed is: 
     
         1 . A device, comprising:
 a matrix comprising (i) a sample receiving zone, (ii) a labeling zone comprising a labeled antibody with specific binding to Group A  streptococcus  antigen, to form a labeled antibody-bound antigen, and (iii) a capture zone comprising a capture antibody that binds the labeled antibody-bound antigen, wherein the sample receiving zone, the labeling zone and the capture zone are arranged on the matrix in a liquid flow path, and   wherein at least one of the sample receiving zone and the labeling zone comprise N-acetyl-D-glucosamine (NAG) monomer to reduce the rate of false positives associated with detection of Group A  streptococcus  infection.   
     
     
         2 . The device of  claim 1 , wherein the labeled antibody with specific binding to Group A  streptococcus  antigen is a polyclonal antibody. 
     
     
         3 . The device of  claim 2 , wherein the polyclonal antibody is fluorescently labeled. 
     
     
         4 . The device of  claim 1 , wherein the labeled antibody with specific binding to Group A  streptococcus  antigen is a monoclonal antibody. 
     
     
         5 . The device of  claim 4 , wherein the monoclonal antibody is fluorescently labeled. 
     
     
         6 . The device of  claim 1 , wherein the capture antibody is a polyclonal antibody. 
     
     
         7 . The device of  claim 1 , wherein the capture antibody is a monoclonal antibody. 
     
     
         8 . A device, comprising:
 a matrix comprising (i) a sample receiving zone, (ii) a labeling zone comprising a labeled antibody with specific binding to Group A  streptococcus  antigen, to form a labeled antibody-bound antigen, and (iii) a capture zone comprising a capture antibody that binds the labeled antibody-bound antigen, wherein the sample receiving zone, the labeling zone and the capture zone are arranged on the matrix in a liquid flow path, and   wherein at least one of the sample receiving zone and the labeling zone comprise a reagent that blocks binding of the labeled antibody with specific binding to Group A  streptococcus  antigen with human epithelial cell wall glycoproteins, to reduce the rate of false positives associated with detection of Group A  streptococcus  infection.   
     
     
         9 . The device of  claim 8 , wherein the labeled antibody with specific binding to Group A  streptococcus  antigen is a polyclonal antibody. 
     
     
         10 . The device of  claim 9 , wherein the polyclonal antibody is fluorescently labeled. 
     
     
         11 . The device of  claim 8 , wherein the labeled antibody with specific binding to Group A  streptococcus  antigen is a monoclonal antibody. 
     
     
         12 . The device of  claim 11 , wherein the monoclonal antibody is fluorescently labeled. 
     
     
         13 . The device of  claim 8 , wherein the capture antibody is a polyclonal antibody. 
     
     
         14 . The device of  claim 8 , wherein the capture antibody is a monoclonal antibody. 
     
     
         15 . The device of  claim 8 , wherein the reagent is selected from the group consisting of N-acetyl glucosamine (NAG), glucosamine, acetyl-galactosamine, galactosamine, mannosamine, acetyl-muramic acid, chitin, chitosan and hyaluronic acid. 
     
     
         16 . A method for detecting the presence or absence of Group A  streptococcus  in a biological sample, comprising:
 providing a device according to  claim 8 ;   placing a biological sample on the device; and   determining the presence or absence of Group A  streptococcus.      
     
     
         17 . The method of  claim 16 , further comprising:
 providing an instrument for collecting the biological sample; and   collecting a biological sample on the instrument.   
     
     
         18 . The method of  claim 16 , further comprising:
 providing instructions for use, wherein the instructions do not caution to not touch the tongue, sides or top of mouth with the instrument when collecting the sample.   
     
     
         19 . A kit, comprising:
 a device according to  claim 1 ;   a container comprising an extraction reagent;   an instrument for collecting a biological sample; and   instructions for use.   
     
     
         20 . The kit of  claim 19 , wherein the instrument is a swab.