A virtual ELISA to quantitate COVID-19 antibodies in patient serum.

Enzyme-linked immunosorbent assays (ELISAs) are used widely in biotechnology, pharmaceutical, and clinical medicine labs. At the same time, they appear to be underrepresented in chemistry and biochemistry curricula, even though their sensitivity, selectivity, and ease of use would argue for their widespread use. We describe here an online ELISA activity suitable for stand-alone use or in conjunction with an actual wet lab ELISA. Specifically, we offer real and mock data for a hypothetical ELISA to detect plasma antibodies to COVID-19 in infected patients who have had the disease. Much of the activity focuses on chemical and mathematical models to fit ELISA or any macromolecule/ligand binding data, a skill that addresses perhaps the most relevant and difficult learning goal of an ELISA experiment.

We describe a virtual online enzyme‐linked immunosorbent assay (ELISAs) lab experience used with 12 junior/senior chemistry majors in April 2020 in a half‐semester advanced biochemistry techniques lab course. The lab was scheduled to meet twice a week (2 × 4 hr) before all classes moved online due to the COVID pandemic. In a 4‐h virtual lab, students screened hypothetical human sera samples for antibodies against SARS‐CoV‐2 (COVID‐19) and studied the chemical and mathematical bases for ELISA data fitting.

ELISAs have detection limits varying between 0.01 pg/ml and 100 ng/ml. Given their robust use in health fields, they are neither widely used in undergraduate biochemistry or chemistry courses, nor are they mentioned in the ACS's Guidelines and Supplements for either Analytical Chemistry or Biochemistry. Few papers have been published involving purely educational uses of ELISAs , , and those that do often center on a specific research project or for use in biotechnology programs. One report documents a hybrid wet‐simulated lab ELISA. Most of the wet‐lab steps in ELISAs involve pipetting skills and can be replaced by a virtual laboratory exercise. Understanding the underlying chemical equilibria and mathematical analyses does not require a wet lab.

Perhaps the most challenging learning goals for ELISAs for students involve understanding the chemical and mathematical equations, choice and use of modeling and analysis software, and test validity/reliability. These goals are consistent with ASBMBs “process of science” skills and the results from the NEEDED MATH Conference, a NSF Advanced Technological Education initiative.

All written materials in support of this lab are found in Data S1–S6. Students were asked to complete prelab activities (videos, , prelab quiz and survey, and reading materials). A brief introduction was given at the start of a 4‐h Zoom class. Students were separated into meeting rooms with a lab partner. The instructor was available through the 4‐h scheduled time to address questions. A POGIL ‐like laboratory introduction and data analysis activity was used (see Data S1–S6). We used actual ELISA plate data developed previously for another activity. In addition, we used simulated data made with a four‐parameter logistic equation to show how changes in parameters affect data fitting. Data analysis was performed using free web software and commercial software available through a 30‐day free license.

The same prequiz was given to students during finals week. The average score improved from a small amount 67.5–70%, but we do not pretend that we have done a rigorous assessment of this online virtual lab activity. Likert scale self‐report surveys show that students understood the chemical principles and each step of the ELISA but still struggled with the math. Most felt that they would have liked a wet lab experiment. In a way these results are not unexpected given it was the last lab of a trying online semester.

This virtual lab should provide a practical and translatable skillset needed in a real‐world lab environment. The provided materials are scalable for future development to address additional concepts including long‐term validation of the assay using statistical analyses of low and high controls and use of ELISA data to make final recommendations for a company or lab.

Data S1 ELISA procedure

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Data S2 COVID‐19 student project 2020

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Data S3 Mock ELISA data

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Data S4 Instructor data graphs

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Data S5 Supplementary quiz ELISAs

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Data S6 Supplementary survey ELISAs

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