Multi-site analytical validation of an assay to detect anti-JCV antibodies in human serum and plasma

Background: JC virus (JCV) infection is a prerequisite for development of progressive multifocal leukoencephalopathy (PML). We previously described the development of a novel, two-step enzyme-linked immunosorbent assay (ELISA) that detects anti-JCV antibodies in human serum or plasma, and the potential clinical utility of anti-JCV antibody status for PML risk stratification.

Objectives: To validate the anti-JCV antibody ELISA at multiple clinical laboratories in order to demonstrate the robustness of the method.

Study design: Analytical validation of the ELISA was performed at four laboratories by evaluation of intra- and inter-assay precision, analytical specificity and sensitivity, matrix interference, robustness, sample and reagent stability.

Results: Analytical validation demonstrated that the assay is sensitive, specific, and precise. The assay sensitivity was estimated at 1.7ng/mL using a humanized anti-JCV monoclonal antibody control. The sensitivity to detect JCV infection was estimated to be 97.5%. The specificity of the assay to discriminate JCV-specific antibodies from antibodies directed to BK virus, a related polyomavirus, was also demonstrated. The inter- and intra-assay precision was ≤6.0% and 9.8% for the screening step and 2.6% and 11.3% for the confirmation step. Results obtained for plasma and serum were highly congruent, and assay robustness was demonstrated by the highly concordant results generated by four laboratories testing a common panel of 100 blinded samples.

Conclusions: The novel, two-step ELISA to detect anti-JCV antibodies in human serum and plasma is robust, and assay performance is consistent and reproducible in multiple laboratories, making it suitable to support testing for global clinical studies.