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Coronavirus Assays for Variants of Concern

Due to amino acid changes that occur during their life cycle viruses change over time. While most changes have little to no effect changes to the coronavirus spike (s) protein have led to the emergence of new variants identified as “variants of concern.”  Initially there were 4 “variants of concern” (Alpha, Beta, Gamma and Delta variants) on the  World Health Organization  (WHO) and the CDC watchlist.  The “variants of concern” designation is assigned based on increased transmissibility, resistance to public health measures and/or virulence.  Thanks to public health and safety measures the previous variants have been downgraded.  In 2022 the dominant circulating “variants of concern” are Omicron and its subvariants (BA.1, BA.2, BA.4, BA.5, BA.2.86, EG.5.1, XBB.1.9.1, BQ.1.1 to name a few). The ongoing evolution of SARS-CoV-2 requires continuous research and development to create a pipeline of effective therapies against COVID-19.

IBT Bioservices offers Coronavirus assays to support research and development challenges to identifying broadly neutralizing candidates to stem the ongoing pandemic. Our recombinant rVSV-SARS-CoV-2 platform can be used to determine the neutralization potency (IC50 value) of anti-infectives against spike-mediated infectivity of Coronavirus variants, including Omicron subvariants. IBT also offers pseudotyped assay for evaluating anti-infectives against Ebolavirus and Marburgvirus.The platform can be used to evaluate proteins, antibodies, as well as small or large molecules.  If you would like to screen your antiviral candidates in our pseudotyped coronavirus assay, use the form below to contact IBT Bioservices.

Fig. 1. Relative light units (luciferase activity) recorded upon infection of Vero cells using IBT’s rVSV-pseudotype SARS-CoV2 Spike.

                    Fig. 1. Luciferase activity (RLU) in Vero cells infected with rVSV-pseudotype SARS-CoV2 Spike.

Key advantages: The spike protein is a key determinant of host and cell tropism, antigenicity and immunogenicity, interspecies transmission as well as pathogenesis1. These traits make the S protein an attractive target for antiviral inhibitors and vaccines2,3,4. Recombinant VSV pseudotyped with the coronavirus spike  (S) proteins are efficient tools for evaluating mechanisms of virus entry and efficacy of anti-infective  candidates. 

Common Name (Origin)
Pango Lineage
Spike Amino Acid Mutations
Wild-type (Wuhan)
Parental Strain
(United Kingdom)

del69–70 HV, del144 Y, N501Y, A570D, D614G, P681H, T761I, S982A, D1118H
(South Africa)
K417N, E484K, N501Y, D614G, A701V
L18F, T20N, P26S, D138Y, R190S, K417T, E484K, N501Y, D614G, H655Y, T1027I
Delta (India)
L452R, E484Q
L452R, D614G
SS13I, W152C, L452R, D614G
D614G (--)



(G75V(77) T76I(77) R246del(245) S247del(245) Y248del(250) L249del(250) T250del
P251del(250) G252del(250) D253N(250) L452Q F490S T547I D614G T859N)
D614G, D950N, E484K, ins145N, N501Y,e P681H,
R346K, T95I, Y144T, Y145S



A67V H69del V70del(69) T95I G142D V143del Y144del(143) Y145del(143) N211del L212I ins214EPE G339D S371L S373P S375F K417N N440K G446S S477N T478K E484A Q493R G496S Q498R N501Y Y505H T547K D614G H655Y N679K(674) P681H(674)N764K D796Y N856K Q954H N969K L981F
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