Variants and Neutralizing Antibodies for SARS-CoV-2 from Sino Biological

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During the last few months, many new variants of the SARS-CoV-2 virus have emerged. The U.K. variant B.1.1.7, the South Africa variant B.1.351, the Brazil variant P.1, and the most recent Indian variant B.1.617 are specifically concerning due to their high prevalence.

A subset of the mutations detected in the RBD domain of the spike protein takes place in more than one strain. Such convergent mutations are of major interest because they could be responsible for causing increased transmissibility. Sino Biological has now introduced RBD and Spike proteins of these variants.

See More Reagents for SARS-CoV-2 Research

Furthermore, the mutations in these strains take place in the nucleocapsid protein, which is generally utilized as the biomarker in rapid antigen tests. It is crucial to evaluate whether the present commercial antigen tests could identify the mutated N proteins with the same level of specificity and sensitivity as their WT counterpart.

A panel of recombinant RBD or Spike and nucleocapsid protein variants designed by Sino Biological can now be used to assess the efficacy of the vaccination and antibodies.

Recombinant SARS-CoV-2 variants (Partial)

**B.1.617 (India*)**

Table 1. Source: Sino Biological Inc.

Lineage	Catalogue	Antigen	Mutations	Tag
B.1.617	40588-V07E16	N	D377Y	His
B.1.617	40589-V08B13 (under development)	S1+S2 ECD	D614G, E154K, E484Q, G142D, H1101D, L452R, P681R, Q1071H	His
B.1.617	40591-V08H19	S1	D614G, E154K, E484Q, L452R, P681R	His
B.1.617	40592-V08H28	RBD	L452R	His
B.1.617 / B.1.617.1 / B.1.617.3	40592-V08H88	RBD	L452R，E484Q	His

**Epsilon | B.1.427/B.1.429 (U.S.A*)**

Table 2. Source: Sino Biological Inc.

Lineage	Catalogue	Antigen	Mutations	Tag
B.1.429/B.1.427	40591-V08H17	S1	W152C, L452R, D614G	His
B.1.429/B.1.427	40588-V07E9	N	T205I	His

**Alpha | B.1.1.7 (U.K.*)**

Table 3. Source: Sino Biological Inc.

Lineage	Catalogue	Antigen	Mutations	Tag
B.1.1.7	40588-V07E1	N	R203K, G204R	His
B.1.1.7	40588-V07E17	N	E378Q	His
B.1.1.7	40588-V07E4	N	I292T	His
B.1.1.7	40589-V08B6	S1+S2 ECD	H69del, V70del, Y144del, N501Y, A570D, D614G, P681H, T716I, S982A, D1118H	His
B.1.1.7	40592-V08H18	RBD	S494P	His

**Beta | B.1.351 (South Africa*)**

Table 4. Source: Sino Biological Inc.

Lineage	Catalogue	Antigen	Mutations	Tag
B.1.351	40588-V07E9	N	T205I	His
B.1.351	40589-V08B11	S1+S2 ECD	D80A, L242del, A243del, L244del, R246I, E484K, K417N, N501Y, D614G, A701V	His
B.1.351	40589-V08B7	S1+S2 ECD	L18F, D80A, D215G, LAL242-244 deletion, R246I, K417N, E484K, N501Y, D614G, A701V	His
B.1.351	40591-V08H10	S1	K417N, E484K, N501Y, D614G	His
B.1.351	40592-V08H85	RBD	K417N, E484K, N501Y	His
B.1.351	40592-V31H2	RBD	E484K	rFc

**Gamma | P.1 (Brazil*)**

Table 5. Source: Sino Biological Inc.

Lineage	Catalogue	Antigen	Mutations	Tag
P.1	40588-V07E11	N	P80R	His
P.1	40589-V08B10	S1+S2 ECD	L18F, T20N, P26S, D138Y, R190S, K417T, E484K, N501Y, D614G, H655Y, T1027I, V1176F	His
P.1	40591-V08H5	S1	T20N, D614G	His
P.1	40592-V08H86	RBD	K417T, E484K, N501Y	His
P.1	40592-V31H5	RBD	K417T, E484K, N501Y	rFc

Neutralization efficacy assay against SARS-CoV-2 variants

A few of the aforementioned mutations could have enabled the virus to evade the neutralizing antibodies. To define these variants, a new panel of monoclonal antibodies has been recently introduced.

Such antibodies reveal the differential neutralizing activities against various variants verified by Competitive ELISA Assay. Most significantly, the B.1.351 and P.1 variants appear to be impervious to a subset of the antibodies.

Table 6. Source: Sino Biological Inc.

Neutralizing Antibodies	WT RBD	Recombinant RBD				Recombinant S1
Neutralizing Antibodies	WT RBD	B.1.1.7	B.1.351	P.1	B.1.617	B.1.617	B.1.429
40150-D001	++	+	++	++	++	++	++
40150-D002	++	+	+	++	++	++	++
40591-MM43	++	++	++	++	++	++	++
40592-MM57	+	+	-	-	+	+	+
40592-R001	+++	+++	-	-	+++	+++	+++
40592-R118	+++	+++	-	-	+	+	+
40592-R117	+++	+++	-	-	+++	+++	+++

+: Neutralizing capacity

The aforementioned recombinant RBD:

WT: 40592-V08B
B.1.1.7 | U.K. variant: 40592-V08H82 (N501Y)
B.1.351 | South Africa variant: 40592-V08H85 (K417N, E484K, N501Y)
P.1 | Brazil variant: 40592-V08H86 (K417T, E484K, N501Y)
B.1.617 | India variant: 40592-V08H88 (L452R, E484Q)

The aforementioned recombinant S1 :

B.1.617 | India Variant: 40591-V08H19 (E154K, E484Q, L452R, D614G, P681R)
B.1.429 | California Variant: 40591-V08H17 (W152C, L452R, D614G)

40150-D001. Image Credit: Sino Biological Inc.

40592-MM57. Image Credit: Sino Biological Inc.