Assays for shiga toxin and shiga-like toxins

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a substantially pure antigenic or peptide protein related to Shiga toxin (ST) or Shiga-like toxins I or II (SLT-II, SLT-II) or SLT-II variants.
The term "related to" refers to a peptide or protein that have the same biological activity as ST, SLT-I, SLT-II or SLT-II variants which have been altered by the substitution of one or more amino acid residues within the sequence by another amino acid of a similar polarity which acts as a functional equivalent thus resulting in a silent alteration.
Provided herein are antibodies to SLT-II, which may or may not cross-react with ST and SLT-I.
ST, SLT-I, SLT-II and SLT-II variants are obtained by the methods of the present invention and may be used in subunit vaccine formulations.
The invention is also directed to methods for removing ST, SLT-I, SLT-II or SLT-II variants from a sample, preferably a biological fluid, comprising binding the toxin to P1 glycoprotein (P1gp) and removing the resulting toxin-P1gp complex from the sample.
In one embodiment, the method of the present invention may be used to obtain substantially pure ST, SLT-I, SLT-II or an SLT-II variant for use in a vaccine formulation by obtaining the toxin in pure form from a culture supernatant.
In another embodiment, the method of the invention may be used to remove the toxin from a biological sample, preferably a body fluid such as saliva, nasal secretion, mucus, blood, pleural fluid, peritoneal fluid, cerebrospinal fluid, or a gastric aspirate.
The present invention is further directed to methods and kits for detecting ST, SLT-I, SLT-II or an SLT-II variant using a sandwich ELISA.
Specifically, a solid phase matrix or carrier with a bound ligand for the toxin, preferably P1gp, is employed to form a complex with the toxin molecules, resulting in the toxin being bound to the carrier.
The toxin is then detected using: a first antibody specific for the toxin (i.
e.
, ST, SLT-I, SLT-II, or an SLT-II variant), followed by a detectably labeled reporter molecule, preferably a labelled second antibody capable of reacting with the first antibody