Method of recovering shiga-like toxins and vaccines comprising inactivated shiga-like toxin

DETAILED DESCRIPTION This invention provides a facile, efficient and reproducible method for recovering biologically active Shiga-like toxins from a sample using an affinity ligand covalently attached to an affinity support.
The method is based on specific elution conditions required to recover the biologically active Shiga-like toxins from the affinity support thereby avoiding the problems associated with the prior art.
The affinity ligand is covalently bound to the support obviating concerns that the ligand may leach from the solid support.
Further, the methods do not utilize any glycoconjugate to effect recovery of the SLT eliminating possible contamination and safety concerns in the preparation of the vaccine.
Accordingly, in one of its method aspects, this invention is directed to a method for recovering shiga-like toxins (SLT) from a sample comprising said toxins which method comprises: i) contacting said sample with an affinity support having an affinity ligand comprising the disaccharide subunit .
alpha.
Gal(1.
fwdarw.
4).
beta.
Gal covalently linked to the affinity support through a compatible linker arm to form a SLT-affinity support complex; ii) separating the SLT-affinity support complex from the sample; iii) recovering free SLT from the complex under basic non-denaturing conditions; wherein the purified SLT is essentially free of glycolipids.
In another of its method aspects, this invention is directed to a method for recovering shiga-like toxin I (SLT-I) from a sample comprising said toxins which method comprises: i) contacting said sample with an inert solid affinity support having a disaccharide subunit .
alpha.
Gal(1.
fwdarw.
4).
beta.
Gal covalently linked to the affinity support through a non-peptidyl compatible linker arm to form a SLT-I/affinity support complex; ii) separating the SLT-I/affinity support complex from the sample; iii) recovering free SLT-I from the complex by contacting the complex with an aqueous solution having a pH of from about 8 to 11 to provide SLT-I in the aqueous solution and the affinity support; iv) separating the aqueous solution from the affinity support