We previously validated a multiplex, ECL-based assay to quantify serotype-specific IgG to 15 serotypes included in an investigational PCV. To address challenges of maintaining the clinical assay for measurement of vaccine-induced antibodies in Phase 3 and beyond, we established a proficiency panel, the first of its kind for Merck serology assays.
The proficiency panel consists of 32 biobroker serum samples selected for antibody concentrations that span the quantifiable range for all vaccine serotypes. Baseline values were established across 12 months and were utilized in reagent stability and technology transfer protocols.
Stability results support use of critical reagents for 2 years, extending expiry for plates and secondary antibody and allowing for flexible storage temperatures for secondary antibody. The technology transfer passed pre-specified acceptance criteria using manual methods, when compared against baseline values established using automation, enabling assay validation using both manual and automated methods.
Establishing a proficiency panel requires selection of appropriate samples, in large volume, and at least one year of testing to establish baseline values. This upfront investment enabled (1) expiry extension for critical reagents, resulting in overall time and cost savings, and (2) successful technology transfer and partial validation in another laboratory using both manual and automated methods.