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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, DA.4 and BA.5). 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
--
Alpha
(United Kingdom)

B.1.1.7/501Y.V1
del69–70 HV, del144 Y, N501Y, A570D, D614G, P681H, T761I, S982A, D1118H
Beta
(South Africa)
B.1.351
K417N, E484K, N501Y, D614G, A701V
Gamma
(Brazil)
P.1
L18F, T20N, P26S, D138Y, R190S, K417T, E484K, N501Y, D614G, H655Y, T1027I
Delta (India)
B.1.617
L452R, E484Q
Epsilon
(California)
B.1.427
B.1.429
L452R, D614G
SS13I, W152C, L452R, D614G
D614G (--)
--
D614G

Lambda
(Peru)


C.37

(G75V(77) T76I(77) R246del(245) S247del(245) Y248del(250) L249del(250) T250del
P251del(250) G252del(250) D253N(250) L452Q F490S T547I D614G T859N)
Mu
(Colombia)
B.1.621
D614G, D950N, E484K, ins145N, N501Y,e P681H,
R346K, T95I, Y144T, Y145S


Omicron
(Various)



B.1.1.529

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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Fig. 1 Survival after challenge with INFV H1N1 A/Pert/261/2009 (Tamiflu-resistant strain). Inoculum 1xLD90=1.0E+05 PFU/mouse
Survival after challenge with INFV H1N1 A/Pert/261/2009 (Tamiflu-resistant strain) 1.0E+05 PFU/mouse
Survival and weight change in BALB/c mice challenged with INFV A/ Texas/36/91 (H1N1) and treated with antiviral Osletamivir Phosphate (Tamiflu)
Lung viral load and Survival (30 % weight loss cut-off) in BALB/c mice challenged with INFV H3N2 A/HK/1/68.

Alpha (UK) – B. 1.1.7 / 501Y.V1

amino acid mutations: del69–70 HV, del144 Y, N501Y, A570D, D614G, P681H, T761I, S982A, D1118H

Beta (South Africa) – B.1.351

amino acid mutations: K417N, E484K, N501Y, D614G, A701V

Gamma (Brazil) – P.1

amino acid mutations: L18F, T20N, P26S, D138Y, R190S, K417T, E484K, N501Y, D614G, H655Y, T1027I

Epsilon (Ca, USA) B.1.427

amino acid mutations: L452R, D614G

SARS-CoV-2 Parental Strain Wild Type (Wuhan)
SARS-CoV-2 D614G Variant

amino acid mutations: D614G

Epsilon (Ca, USA) B.1.429

amino acid mutations: S13I, W152C, L452R, D614G

SARS-CoV-2 Delta Variant

amino acid mutations: L452R, E484Q

Wishing You a Happy Thanskgiving!

In observance of Thanksgiving our offices will be closed Thursday November 24th through Sunday November 27th. We will resume normal business hours Monday November 28th. Please excuse any delayed responses during this period.

We look forward to assisting you with all your preclinical product and testing needs after the holiday. Happy Thanksgiving!

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