Three questions to Dr. Lei Pei & Dr. Carla Gonzalez, Scientists

1. As a scientist you have been involved in developing and utilizing the VERB assay, what do you appreciate most about the assay?

Dr. Carla Gonzalez: In my opinion, one of the greatest features of the VERB assay is its versatility. It allows not only the isolation of intact SARS-CoV-2 viral particles from different samples, but also the detection of neutralizing antibodies, among others.

Dr. Lei Pei: The VERB platform overcomes the common barriers to efficient detection of intact SARS-CoV-2, enabling to capture, concentrate, and preserve low abundance targets from complex biological or clinical samples.

2. What potential do you see for the VERB assay as a tool in research?

Dr. Carla Gonzalez: As a tool for researchers, the VERB assay has a great potential mainly because it allows the isolation of different SARS-CoV-2 variants. In addition, it enables the development of immunity monitoring research, as well as enabling research based on ACE2 interacting molecules.

Dr. Lei Pei: We are now having more tools for SARS-CoV-2 research, the VERB kit is, for sure, one of them. The potential I see for our assay is to be universal to all SARS-CoV-2 variants, which is very important to monitor the emerging new variants of concern (VOCs).

3. What was your greatest learning during the health crisis of the Coronavirus pandemic?

Dr. Carla Gonzalez: During the pandemic, healthcare systems around the world have been challenged to find diagnostic systems that provide fast and accurate results, allowing them to make quick clinical decisions. Furthermore, another challenge was the need to bring the diagnosis to settings with limited resources. While PCR has been the gold standard of within-the-laboratory testing accuracy, it has its limitations such as time and high cost, the need for qualified personnel, and equipment. That is why the development of accurate point-of-care diagnostic devices could solve clinical issues related to resource/time commitment.

Dr. Lei Pei: A universal tool is very important for the viruses that are constantly evolving and changing.

SARS-CoV-2 infection initiation

The severe acute respiratory syndrome (SARS) like coronaviruses SARS-CoV and SARS-CoV-2 utilize the human cell surface carboxypeptidase angiotensin-converting enzyme 2 (ACE2) as entry receptor (Donoghue et. al. 2000, Li et. al. 2003, Hoffmann et. al. 2020).

Angiotensin-converting enzyme ACE2 is a zinc dependent metalloprotease anchored in the cell membrane. It is part of the Renin-Angiotensin-Aldosterone System (RAAS) and Kinin-Kallikrein System (KKS) and therefore involved in regulation of vasodilation, inflammation, tissue repair and cell proliferation (Cooper et. al. 2021). ACE2 is expressed in intestines, kidney, heart, adipose tissue, lungs, and blood vessels to different levels (Cooper et. al. 2021).

Interaction with the cellular receptor is mediated by the receptor binding domain (RBD) on the S1 subunit of the coronaviral spike (S) glycoprotein (Li et. al. 2003, Du et. al. 2009, Hoffmann et. al. 2020). SARS-CoV-2 infectivity is augmented by the cell surface receptor neuropilin-1, potentially facilitating virus-receptor interactions in respiratory and olfactory cells with low ACE2 expression (Cantuti-Castelvetri et. al. 2020). Beside the main cell surface receptor ACE2, SARS-CoV viruses can also bind to host cell receptors DC-SIGN (dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin) and L (liver/lymph node) - SIGN, promoting the infection of cells with low or absent ACE2 expression (Amraei et. al. 2021, Du et. al. 2009). After establishment of the receptor interaction, the S glycoprotein undergoes priming by the host protease furin at S1/S2 and transmembrane protease serine protease -2 (TMPRSS) at the S2’ site as a prerequisite for the fusion of viral and cellular membranes (Hoffmann et. al. 2020, Vkovski et. al. 2021, Hoffmann et. al. 2020 - 2). SARS-CoV-2 can also be internalized via the clathrin-mediated endocytosis (Jackson et. al. 2022).

Antibodies raised against the spike protein prevent SARS-CoV-2 infection and demonstrate the crucial role of its interaction with the host cell receptor for infection initiation (Hoffmann et. al. 2020).

The Virus Entry Receptor Binding (VERB) assay developed by Covirabio mimics the major initiation step of SARS-CoV-2 infection which is the binding of the virus to ACE2 on the surface of host cells.

References

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