High Throughput ELISA Testing With Hamilton

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The emergence of COVID-19, the disease caused by the novel coronavirus SARS-CoV-2, has challenged the world to rapidly develop testing infrastructure in an unprecedented way. Part of the need for testing is to detect anti-SARS-CoV-2 antibodies. The reasons why serological testing is important are numerous, including but not limited to:

Determining the infection fatality rate
Identifying potential donors of convalescent plasma
Understanding whether previous infection confers immunity

Many SARS-CoV-2 antibody test kits have entered the market but some have unfortunately underperformed with regard to sensitivity and specificity of the presence of antibodies. Now, more than ever, high throughput ELISA testing has changed the speed and accuracy of results, helping speed up testing during a public health emergency.

ELISA Testing for the Detection of Anti-SARS-CoV-2 IgG

Immunoassays are ideal for addressing the need for effective SARS-CoV-2 antibody specific testing. These tests, known as Enzyme-Linked ImmunoSorbent Assays (ELISAs), are widely used and trusted by research and diagnostic laboratories around the world. They demonstrate high sensitivity and specificity for the target analyte which is essential to having a meaningful impact on controlling COVID-19 infection.

Performing this type of test manually opens the possibility for human error and can increase the turnaround time for crucial results, especially considering the current need to process large numbers of antibody testing samples. For this reason, Namida Lab has developed an automated system for high-throughput processing of thousands of serology samples per day to meet the testing demand of employers and large population studies. The system utilizes the Hamilton Microlab® STARplus and integrated devices to fully automate a commercially available anti-SARS-CoV-2 ELISA.

Materials and Methods for Serological Testing

Automated SARS-CoV-2 ELISA

Human serological samples were analyzed for the presence of anti-SARS-CoV-2 IgG using Eagle Biosciences (Nashua, NH) EDI™ Novel Coronavirus COVID-19 IgG ELISA kit per the manufacturer’s recommendation on the Hamilton (Reno, NV) Microlab STARplus automated liquid handling platform. Briefly, serological testing samples were diluted 100-fold and 100 μL of samples and controls were plated according to the plate map on the next page. Assay plates were washed using an integrated Biotek® 405™ LS microplate washer. Final absorbance measurement was taken at 450 nm using an integrated Biomed plate reader.

Results and Discussion of Serum ELISA Testing

Namida Lab’s automated platform utilizes the Eagle Bioscience EDI™ Novel Coronavirus COVID-19 IgG ELISA kit on a Hamilton STARplus liquid handling robot with integrated peripheral devices. This ELISA is a qualitative test that detects the presence of anti-SARS-CoV-2 IgG through human serum ELISA testing with positive and negative controls included in each assay plate (Figure 1).

The assay is fully-automated from loading serological samples through reading assay plate absorbance. Using Hamilton’s Venus Dynamic Scheduler, assay plates are processed in parallel under continuous operation of the system to yield the highest throughput possible (Figure 2). The technician loads samples and consumables onto the system when prompted to enable the uninterrupted flow of sample dilution and assay plate processing.

As a comparison, intra-plate precision was analyzed for positive and negative control samples using both the automated system and manual preparation by a trained technician. Automated ELISA processing yielded less variability as compared to data generated from manual preparation (Table 1).

When the ELISA is performed manually by a technician, approximately six assay plates can be processed per shift as compared to 18 plates on the automated platform (Table 2). When considering that a single technician can operate the liquid handling instrument, the throughput benefits become clear. Another benefit of using liquid handling robotics is the improvement in assay sensitivity and specificity. When performed manually the ELISA demonstrated 94% sensitivity and 100% specificity, where the automated platform achieved 100% sensitivity and 100% specificity.

Conclusion

The data reported here demonstrates the efficiency of automation and the ability of liquid handling robotics to meet the demand for high-throughput antibody testing during the COVID-19 pandemic. Namida lab is able to process up to 3,000 patient samples per day and can report results within 24 hours using their STARplus ELISA platform. The system is operated by a single technician, which enables physical distancing among laboratory technicians and the safe operation of the instrument. Furthermore, liquid handling automation delivers highly reproducible pipetting and assay plate processing that yields lower variability in results and reduces the possibility for human error.

Authors: Mike Rutherford¹, Jen Morio¹, Lindsay Rutherford¹, Adan Orta², Steve A Smith², John Tipton², Cole Yancey², Casey Snodgrass² ¹Namida Lab, Fayetteville, AR, USA. ²Hamilton Company, Reno, NV, USA