Research Solutions for Coronavirus – Genetex

On 26 November 2021, the WHO designated the SARS-CoV-2 variant B.1.1.529 to be the fifth Variant of Concern (VOC) and assigned it the name “Omicron”. Of the more than 50 mutations in its genome, at least 32 are in the spike protein with fifteen point mutations in the RBD (Figure 1), including several found in other VOCs linked to increased transmissibility and immune evasion. Like other VOCs, mutations are also found in Omicron’s nucleocapsid protein (Figure 2). Omicron is widely distributed and is outcompeting Delta. Though it appears to cause more mild disease, it nevertheless has driven increased hospitalizations.

Figure 1. Spike mutation sites in Omicron

Figure 2. Nucleocapsid protein mutation sites in Omicron

GeneTex has a wide range of recombinant antibody and protein reagents for Omicron research. Notably, nucleocapsid antibodies whose immunogens do not contain any Omicron mutation sites are shown in Figure 2.

Highlighted Antibodies

Lateral Flow Assay (Recommended Antibody Pairs)

Omicron Spike RBD and Nucleocapsid Recombinant Proteins

Recombinant Antibodies that detect Omicron

Sandwich ELISA that detects Omicron variants

Table 1. SARS-CoV-2 Variant Detection by GeneTex Spike Antibody Clones

Recombinant nucleocapsid proteins derived from different SARS-CoV-2 variants were assayed by ELISA (either indirect or sandwich ELISA) using the specified GeneTex monoclonal antibodies.

Lateral Flow Assay (Recommended Antibody Pairs)

GeneTex continues to expand and validate its comprehensive catalog of outstanding antibodies and reagents for SARS-CoV-2 (COVID-19) research. This includes ongoing assessment of our antibodies’ ability to detect important viral variants, particularly the WHO-designated Variants of Concern (VOCs). For more information, please see Tables 1-2 below.

In GeneTex’s SARS-CoV-2 spike antibody portfolio, the anti-spike RBD [HL1014] and anti-spike S1 [HL13402] recombinant rabbit clones exhibit high affinity for all SARS-CoV-2 spike proteins, including those of the B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma), and B.1.617.2 (Delta) variants (Table 1). Clone [HL13402] also performs exceptionally well when paired with the widely published mouse clone [1A9] (against the S2 subunit) for sandwich ELISA.

GeneTex’s recombinant rabbit nucleocapsid antibodies display high affinity for the WIV04/2019 (reference sequence) human cell-expressed full-length SARS-CoV-2 nucleocapsid protein, with EC50 values ranging from 0.006-0.074 nM. Importantly, one matched nucleocapsid antibody pair (i.e., GTX635689 and GTX635686) demonstrates superior sensitivity in sandwich ELISA and lateral flow assays. This pair also recognizes the nucleocapsid protein of the B.1.617.2 (Delta) variant, as do several other individual recombinant clones (Table 2).

Taken together, GeneTex’s large selection of SARS-CoV-2 antibodies virtually guarantees that you will find a reagent appropriate for your desired application.

There are multiple SARS-CoV-2 variants currently spreading across the planet, with four of them being designated “Variants of Concern” (VOC) by the World Health Organization (WHO). Several nomenclature systems for these variants exist, and the Greek alphabet designation introduced by WHO is the latest (Table 1). All four of these viruses have mutations (~seventeen to twenty-three) at different points in their genomes, with eight to eleven of these alterations occurring in their respective spike proteins (all have D614G, Figure 1). At this point, most experts think the present vaccines will have efficacy against these variants though there is some unease among scientists and physicians about increased transmissibility and virulence, particularly in regions with low vaccination rates. As the greatest interest has focused on the spike mutations, we offer the following images to illustrate their location in these genomes.

Table 1. VOC Nomenclature

Figure 1. Identified Mutations in VOC Spike Proteins

Table 2. Key VOC Spike Protein Mutations

B.1.1.7 (SARS-CoV-2 Alpha)

In late 2020, the United Kingdom reported the B.1.1.7 variant (aka Alpha) that appears to be significantly more transmissible and perhaps more virulent. Eight of its twenty-three mutations are in the spike protein, with N501Y in the receptor binding domain (RBD) being of most concern as it may be involved in increased ACE2 affinity.

B.1.351 (SARS-CoV-2 Beta)

In January of 2021, the B.1.351 variant (aka Beta) was found in South Africa. It has twenty-one mutations, with eight being in the spike protein. As with the other two variants, it includes the N501Y mutation but also has two additional RBD mutations (E484K, K417N). It appears to be more transmissible, and the E484K mutation is worrisome as it was shown to reduce antibody recognition.

P.1 (SARS-CoV-2 Gamma)

Near the end of January 2021, Japanese authorities reported a new SARS-CoV-2 virus variant obtained from four Brazilian travelers. This variant is designated P.1 (aka Gamma) and has seventeen mutations, with eleven in spike. Some evidence suggests that this virus may also be more transmissible and have some immune escape capability. It has mutations at the same three RBD residues that are altered in the Beta genome.

B.1.617.2 (SARS-CoV-2 Delta)

B.1.617 was first detected in Maharashtra, India in December 2020. There are three sublineages categorized, with B.1.617.2/Delta being designated a VOC due to reports that it is now dominant in many countries, including India and the UK. The B.1.617.2 variant carries ten mutations in spike protein and may be more resistant to neutralization by vaccines and certain monoclonal antibody therapies.

B.1.1.529 (SARS-CoV-2 Omicron)

On 26 November 2021, B.1.1.529 was designated by WHO as a VOC named Omicron. This variant has more than thirty mutations, with three small deletions and one insertion in the spike S1 region, and fifteen point mutations in the RBD. Infection of Omicron variant increased steeply, raising the concerns whether the combination of these mutations may lead to increased transmissibility and immune escape properties.

GeneTex is now developing reagents to support research into these SARS-CoV-2 variants, beginning with recombinant spike/RBD proteins that include many of these key mutations.

RBD of the South Africa variant (501Y.V2 / B.1.351)

GTX136022-pro

RBD of the UK variant (501Y.V1 / B.1.1.7)

GTX136014-pro

Spike RBD (K417T, E484K, N501Y Mutant) Brazil variant
GTX136043-pro

SARS-CoV-2 (COVID-19) nucleocapsid antibody

(GTX135357)

SARS-CoV / SARS-CoV-2 (COVID-19) ORF7a antibody [3C9]

(GTX632602)

SARS-CoV / SARS-CoV-2 (COVID-19) NSP8 antibody [5A10]

(GTX632696)

TMPRSS2 antibody [N2C3]

(GTX100743)

SARS-CoV / SARS-CoV-2 (COVID-19) spike antibody [1A9]

(GTX632604)

SARS-CoV / SARS-CoV-2 (COVID-19) nucleocapsid antibody [6H3]

(GTX632269)

ACE2 antibody [N1N2], N-term

(GTX101395)

SARS-CoV-2 (COVID-19) spike antibody

(GTX135356)

Additional Antibodies

SARS-CoV-2 (COVID-19) nucleocapsid protein

(GTX135357-pro)

Human ACE2 protein (active)

(GTX01179-pro)

SARS-CoV-2 (COVID-19) Spike S1 protein, His and Avi tag (active)

(GTX01548-pro)

SARS-CoV-2 (COVID-19) Spike RBD protein, His tag (active)

(GTX01546-pro)

The GeneTex SARS-CoV-2 (COVID-19) Nucleocapsid Protein Sandwich ELISA Kit (GTX535824) is a ready-to-use in vitro assay for the quantitative measurement of SARS-CoV-2 nucleocapsid (N) protein. It allows highly specific, ultrasensitive detection of SARS-CoV-2 N protein with an average lowest detection limit of 18 pg/ml (Figure 1). The assay can be completed in less than four hours.

Figure 1. GeneTex’s SARS-CoV-2 (COVID-19) Nucleocapsid Protein Sandwich ELISA Kit demonstrates superior sensitivity for SARS-CoV-2 nucleocapsid protein compared to a competitor’s kit.

A key feature of this kit is a low background when testing plasma samples and a significantly decreased rate of false positives (Table 1). In addition, the optimized reaction formula generates a reliable recovery value for plasma samples, highlighting this kit’s outstanding performance when compared to similar products on the market (Table 2).

Table 1. GeneTex’s SARS-CoV-2 (COVID-19) Nucleocapsid Protein Sandwich ELISA Kit produces very low noise signal for control plasma samples.

Table 2. GeneTex’s SARS-CoV-2 (COVID-19) Nucleocapsid Protein Sandwich ELISA Kit generates a reliable recovery value* for human plasma compared to a competitor’s kit.

* The recovery rate is utilized to determine the differences in percent recovery between samples and standard diluent. The ideal recovery rate is 100%.

The SARS-CoV-2 (COVID-19) N protein is abundantly expressed during infection. It is one of four viral structural proteins, and binds the virus’s genomic RNA to form a helical ribonucleocapsid complex. N protein functions in viral genome protection, replication, virion assembly, and immune evasion. Through scrupulous design, production, and stringent testing, GeneTex has successfully developed a panel of recombinant monoclonal antibodies against SARS-CoV-2 (COVID-19) nucleocapsid protein and other antigens. The GeneTex SARS-CoV-2 (COVID-19) Nucleocapsid Protein Sandwich ELISA Kit (GTX535824) is composed of an antibody pair carefully selected to provide the highest signal-to-noise ratio for nucleocapsid detection in various sample types. This product represents another important addition to GeneTex’s growing catalog of SARS-CoV-2 reagents created to accelerate your COVID-19 research.

This kit is for research use only and not for use in diagnostic or therapeutic applications.

A neutralizing RBD antibody for all four variants!

Neutralizing Spike RBD antibody [HL1002] GTX635692

Rabbit Monoclonal

Inhibition analysis tested

Inhibits RBD protein binding to human ACE2.

– WT

– 2 UK variants

– South Africa variant

– Brazil variant

RBD ACE2 Binding Activity / Neutralization Assay Panel (GTX300122)

A handy panel to set up neutralization assay for neutralizing antibodies detection and inhibitory activity of test factors (e.g., small compounds).

• 5 SARS-CoV-2 RBD proteins are provided, including four current major variants
• Human ACE2 protein
• Recombinant proteins are expressed by HEK 293
• A control neutralizing antibody is provided