Use of a Microfluidic Platform To Evaluate and Predict Reagent Performance in Microtiter Plate-Based Immunoassays.

Selection and characterization of antibodies are critically important in establishing robust immunoassays to support the development efforts of vaccines. Plate-based ELISA can be time- and resource-intensive to select initial antibody clones or characterize downstream resupply lots while providing limited information regarding the binding characteristics of the antibodies beyond concentration-response curves. This work applied the microfluidic Gyrolab to holistically evaluate immunoassay reagents through analyses of concentration-response curves as well as antibody-antigen interactions visualized in column images and affinity estimates. We exploited the automation capability of the Gyrolab to reduce the resources (time, reagents, and scientists) required for screening and evaluating antibody reagents. Using a flexible semi-universal assay format, we compared antibody clones for selection and resupply lots of sera and monoclonal antibodies in a simple "plug-and-play" manner without antibody modifications. We found that the performance of antibodies in the Gyrolab correlated well with the trends observed in traditional ELISAs, while the Gyrolab provided additional advantages over plate-based assays such as column images of antibody binding and affinity measurements.

Evaluation of a digital dispenser for direct curve dilutions in a vaccine potency assay.

Dilutions are a common source of analytical error, both in terms of accuracy and precision, and a common source of analyst mistakes. When serial dilutions are used, errors compound, even when employing laboratory automation. Direct point dilutions instead of serial dilutions can reduce error but is often impractical as they require either large diluent volumes or very small sample volumes when performed with traditional liquid handling equipment. We evaluated preparation of dilution curves using a picoliter digital dispenser, the HP, Inc. / TECAN D300 which is capable of accurately delivering picoliter volumes directly into sample wells filled with assay diluent. Dilution linearity and variability of the direct dilutions were similar to or less than those generated with a traditional liquid handler as measured using a fluorophore assay and an ELISA used to measure vaccine potency. Minimum concentrations for detergent in the dispensed sample were identified but no correlation with detergent characteristics was observed. The tolerance to protein in the sample was evaluated as well with up to 5% BSA having no impact on dispense linearity and precision. We found the digital dispenser to reduce automation complexity while maintaining or improving assay performance in addition to facilitating complex plate lay-outs.

A semi-universal assay platform to quantitate vaccines with potential applications for biotherapeutics.

AIM: Biologics development often requires multiple immunoassays to evaluate both assay reagents and potential drug candidates resulting in extensive analytical development. METHODOLOGY: We developed a semi-universal, 5-layer platform assay on Gyrolab using secondary antispecies or anti-isotype-specific capture and detection antibodies. We applied the assay to several multivalent vaccines. RESULTS: Method performance exhibited a median accuracy of 110%, reproducibility of 9% CV and intermediate precision of 11% CV. System suitability criteria were met for 92.5% of the samples and only one out of 31 replicate samples exhibited a %CV greater than 20%. CONCLUSION: The semi-universal Gyrolab assay allowed assay development without reagent labeling. The format could also be translated into a plate-based assay.

Quality by design for a vaccine release immunoassay: a case study.

BACKGROUND: As quality by design (QbD) for pharmaceutical product development is being expanded to include analytical methods, we applied QbD to the development of antigenicity assays measuring in vitro relative potency of a quadrivalent vaccine candidate. RESULTS: After establishing development targets together with customers, immunoassays were developed to meet objectives. Statistical design of experiments was used to optimize method parameters and establish a design space. Systematic risk analysis enabled identification of potential risks to method performance that were mitigated by investigating the available design space around risk factors and by establishing appropriate control strategies. CONCLUSION: We found QbD-based method development was a more efficient and systematic approach that could also potentially facilitate assay transfers and life cycle management.

Pharmacokinetic immunoassay methods in the presence of soluble target.

Soluble targets represent a special challenge when employing ligand binding assays to support pharmacokinetic analysis of monoclonal therapeutics. Target-engaged antibody is not available for binding in immunoassays employing anti-idiotype-specific antibodies or target for capture. We investigated several formats of total antibody assays that show reduced interference of soluble targets: direct target capture, indirect target capture and acid dissociation. While indirect target capture worked well for a regular affinity antibody against DKK1, a high affinity antibody against PCSK9 required an additional acid dissociation step. The choice of a suitable format was antibody and target dependent. Our results offer several choices to approach immunoassay development for soluble targets.