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

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.

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)
D614G, E154K, E484Q, G142D,
H1101D, L452R, P681R, Q1071H
B.1.617 40591-V08H19 S1 D614G, E154K, E484Q, L452R,
B.1.617 40592-V08H28 RBD L452R His
B.1.617 /
B.1.617.1 /
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
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
D80A, L242del, A243del, L244del, R246I,
E484K, K417N, N501Y, D614G, A701V
B.1.351 40589-V08B7 S1+S2
L18F, D80A, D215G, LAL242-244 deletion,
R246I, K417N, E484K, N501Y, D614G, A701V
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.

WT RBD Recombinant RBD Recombinant S1
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.