Thread by @jbloom_lab

We've written detailed protocol on neutralization assays for #SARSCoV2 at biosafety-level-2 using lentiviral pseudotype, and put key reagents (293T-ACE2 cells, plasmids) in BEI Resources repository. Most labs should be able to perform these assays (1/9).
biorxiv.org/content/10.110…

Why is this useful? Most serology assays (e.g. ELISA) measure antibodies that *bind* virus. But for many viruses, including coronaviruses (e.g., Table 3 of ncbi.nlm.nih.gov/pubmed/2991366), neutralizing antibodies correlate more w protection from disease than binding antibodies. (2/9)

So for purposes like convalescent sera transfer and studying immunity, neutralization assays probably more informative than binding assays. Unfortunately, neutralization assays harder to perform as they require using an infection-capable virus. (3/9)

The gold standard is to use actual #SARSCoV2, but that has to be done at biosafety-level-3 which precludes most labs. A second option is to pseudotype #SARSCoV2 Spike on a "safer" virus like a lentivirus, retrovirus, or VSV to enable assays. (4/9)

Several groups have done this (we did *not* invent approach!). But surprisingly difficult to get it working well, and many labs want to perform assays ASAP. So we've written above protocol and put reagents in BEI Resources. (5/9)

Plasmids express codon-optimized Spike on surface of stripped-down HIV-based lentiviral particles expressing luciferase or fluorescent protein, these infect 293T cells engineered to express ACE2. No modified Spike tail, luciferase "titers" of 1e6-1e7 RLUs /ml. (6/9)

Plasmids / cells are deposited with BEI Resources, should be available to anyone soon. If you want them sooner, e-mail us exactly what you want + address + FedEx code and we will mail them. (7/9)

Note this is just one of several approaches for #SARSCoV2 neut assays. Others (e.g., @VirusWhisperer) developing assays with more throughput + standardization. So use this system to start now, but keep eyes open for improvements--and share if you find a way to improve. (8/9)

Most credit goes to @khdcrawford (@HutchBasicSci @uwgenome @UW_MSTP grad student) who got this working and was enthusiastic about making it share-able. Help from Rachel, @AdamDingens, Andrea, Keara in our lab, plus @BalazsLab @HelenChuMD @KingLabIPD @veeslerlab. (9/9)