First Cell-Free NAb Assay with Superior Sensitivity and Precision Analyzes COVID-19 Immune Response

By LabMedica International staff writers
Posted on 26 Aug 2022

Image: NAB-Sure SARS-CoV-2 Assay quantifies wild type SARS-CoV-2 virus neutralizing antibodies using qPCR workflows (Photo courtesy of Spear Bio)

Pharmaceutical drug developers and healthcare researchers need innovative tools to understand COVID-19 immune response and validate vaccines and therapeutics critical to managing the pandemic. Neutralizing antibody (NAb) assays are useful for understanding individual and population immunity against SARS-CoV-2. Study of the antibody response to SARS-CoV-2 provides invaluable data for clinical trials and the development of vaccines to fight the spread of the virus. NAb assays are required components of the clinical trials that identify the effectiveness of a new vaccine against a virus or its compatibility with existing drugs and treatment. Now, a new SARS-CoV-2 NAb test allows labs to work with diverse types of biospecimens and sizes of samples, including serum, plasma, and micro-sampling techniques like dried blood spots (DBS), providing consistent laboratory-to-laboratory results even when comparing different sample types.

The NAB-Sure SARS-CoV-2 Neutralizing Antibody Test Kit from Spear Bio (Woburn, MA, USA) that has been developed by former Harvard University scientists based at the Wyss Institute for Biologically Inspired Engineering (Cambridge, MA, USA) provides a surrogate virus neutralization assay with much higher sensitivity than standard ELISA test formats and cell-based approaches. The NAB-Sure SARS-CoV-2 test kit simplifies testing for SARS-CoV-2 NAbs, producing qualitative and quantitative NAb titer measurements using real-time polymerase chain reaction (PCR). The assay has the accuracy of cell-based assays like the plaque-reduction neutralization testing (PRNT), the gold standard for NAb detection, without the safety concerns and long, complicated workflows. What's more is the assay's capability to analyze small volumes of serum or plasma enables new micro-sampling techniques to be leveraged during collection.

The NAB-Sure SARS-CoV-2 Assay provides an inter-laboratory coefficient of variation (CV) of 4.8% even for extremely small test sample sizes such as a DBS from a finger prick. The test results can help researchers validate vaccines and develop predictive models for antibody durability. Automation compatibility combined with industry-leading accuracy for small volumes promotes high throughput and reduces cost at every stage of testing: sample collection, detection, and analysis.

"Conventional cell-based methods for SARS-CoV-2 neutralizing antibody measurement have poor lab-to-lab consistency," said Spear Bio CTO and co-founder, Feng Xuan. "NAB-Sure SARS-CoV-2 Assay is the first cell-free NAb assay with superior sensitivity and precision. This performance combined with simplified workflows is an opportunity to standardize neutralizing antibody measurements, which is essential for the vaccine validation needed at this stage of the pandemic."