Pseudotyped S protein screening assay

 

Antibody Analytics is developing a screening assay to characterise the ability of therapeutic antibodies or small molecule inhibitors to block the entry of SARS-CoV-2 into healthy cells. We are establishing an in vitro assay using pseudotyped virus expressing the spike (S) protein of SARS-CoV-2 and human cells expressing ACE2 – the viral entry receptor for SARS-CoV-2. This assay is suitable for the assessment of:

• Therapeutic antibodies which aim to inhibit viral entry
• Small molecule inhibitors, targeted towards ACE2, the S protein or the priming proteases essential for S protein-mediated viral entry
• Assessment of sera for neutralising antibody responses (e.g. from experimental vaccines)

In this in vitro model of the infection process, the pseudotyped virus expresses two reporter genes. The mCherry reporter provides a marker for detailed flow cytometric analysis at a cellular level and the luciferase reporter lends itself to medium-throughput screening of compound/antibody libraries.

This assay provides a complementary, orthogonal approach to our Cell Fusion Screening format.

Cell fusion screening assay

 

Exploiting an observed coronavirus-induced phenomenon, Antibody Analytics is developing a cell fusion assay to assess the ability of molecules or antibodies to interfere with the interaction of the viral spike (S) protein from SARS-CoV-2 and ACE2 (the human receptor essential for viral entry).  Cells expressing ACE2 are co-incubated with cells expressing the viral S protein. Cell-cell fusion occurs, generating a fluorescent signal. Blocking this interaction provides a measurable reduction in fluorescence.

This assay is suitable for the assessment of:

 

• Therapeutic antibodies which aim to inhibit viral entry
• Small molecule inhibitors, targeted towards ACE2, the S protein or the priming proteases essential for S protein-mediated viral entry
• Assessment of sera for neutralising antibody responses (e.g. from experimental vaccines)

This assay provides a complementary, orthogonal approach to our pseudotyped S protein screening assay format.

Flow-based blocking assay

 

Antibody Analytics have developed a pair of complementary cell-based blocking assays which can be used to identify modalities that can block the interaction of the viral S protein of SARS-CoV-2 and the human receptor, ACE2. The interaction of cells engineered to express the viral S protein with soluble ACE2 can be measured by flow cytometry, thus, agents that interfere with this interaction can be identified.

And vice versa. We have genetically engineered cells to express human ACE2, where interference can be measured by the ability to block the interaction of the cells with the soluble S protein.

These assays are also suitable for the assessment of:

• Therapeutic antibodies which aim to inhibit viral entry
• Small molecule inhibitors, targeted towards ACE2, the S protein or the priming proteases essential for S protein-mediated viral entry
• Assessment of sera for neutralising antibody responses (e.g. from experimental vaccines)