Shiga toxins (Stx) play an important role in the development of hemolytic uremic syndrome (HUS), a life-threatening complication, caused by pathogenic Stx-producing Escherichia coli (E. coli). Stx have to enter into the circulatory system before they are delivered to target organs and cause damage. The presence of Stx in sera could be a risk indicator for HUS development. However, detection of Stx, particularly Stx2, has been difficult due to the presence of Stx2-binding components in human serum. Here, we report new ELISA-based methods for the detection of Stx1 and Stx2 in human serum. The recovery rate for Stx2 was 62% when Stx2-spiked serum samples were treated with guanidinium chloride at a concentration of 200 mM, in contrast to 17% without guanidinium chloride treatment and Stxs were detected in all serum samples obtained from STEC-infected patients using the new methods. A specific physical interaction between Stx2 and human serum amyloid P component (HuSAP) in human sera was demonstrated by pull-down assays. However, our results suggested that HuSAP was not the only inhibitory factor for detection of Stx2 in human serum. This study demonstrates that treatment of serum samples with guanidinium chloride may be useful for laboratory diagnosis of STEC infections.

Improvement of immunoassays for detection of Shiga toxins in human serum

256th National Meeting (2018)

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