SARS-CoV-2 diagnostics: Towards a more comprehensive approach to routine patient testing

By: Dave Lowe

Key Takeaways

• Assessment of the SARS-CoV-2 response at the structural level was performed using the One Lambda COVID Plus Assay.
• The study indicates that the antibody response is shown to be both quantitatively and qualitatively different between individuals.
• A memory response involving the T-cell compartment has been demonstrated, which shows variation between individuals.

Summary Statement

Assessment of the antibody response to SARS-CoV-2 at the structural level using the COVID Plus assay demonstrated significant differences between individuals.

Summary

This study by Carter et al. explores a major gap in our understanding of SARS-CoV-2 infection, namely the generation of protective immunity following exposure. To investigate this further, the group adapted a well-established approach to assess cellular immunity post SARS-CoV-2 infection, and they utilized the LABScreen™ COVID Plus assay to provide a semi-quantitative readout of antibody reactivity at the viral structural level.

By studying 12 staff members from their own institution that had previously reported symptoms consistent with COVID-19 with diagnosis confirmed clinically or by PCR, the group initially measured the presence of SARS-CoV-2 IgG antibodies with commercial ELISA assays. Those individuals who tested positive for antiviral responses were then assessed for virus specific functional T-cell immunity and a more detailed analysis of their SARS-CoV-2 antibody response was conducted using the LABScreen COVID Plus multiplex assay.

With an antigenic re-stimulation with SARS-CoV-2 specific peptides, the researchers observed that in the majority of antibody positive individuals, an in-vitro T-cell response could be generated. Results of testing with the LABScreen COVID Plus assay showed good correlation with the ELISA based assays which detect IgG directed against Spike (S) and nucleocapsid (N) proteins respectively.

Importantly, the authors showed that the LABScreen COVID Plus assay was able to provide additional information on antibody specificity with observed reactivity towards individual components of the S protein. The authors also showed the contribution of antibody directed against the distinct viral structural components as detected by the assay and this revealed significant intra-individual differences in reactivity. Additionally, marked inter-individual differences were observed in total anti-SARS-CoV-2 antibody levels.

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