Sensitive and accurate diagnostic test of COVID-19 using high quality SARS-CoV-2 protein

The coronavirus pandemic has a major impact on our daily lives. As of September 20, more than 30 million people have the disease and about 100,000 have died worldwide.¹

This virus has several important characteristics. The incubation period is up to 14 days and can be transmitted before the onset. Coupled with the slow mobilization of diagnostic tests, the relatively small asymptomatic population has led to some countries imposing national blockades to limit the spread of the virus.^1,2

These measures helped reduce the number of cases and the number of reproductions, and many of these countries later lifted the blockade restrictions.

Unfortunately, there are no vaccines currently available SARS-CoV-2, Removing these restrictions can actually lead to new outbreaks. This scenario has already been seen in Germany.³

Therefore, an accurate diagnosis of SARS-CoV-2 is essential for identifying new outbreaks and implementing timely quarantine measures to limit the spread of the infection and ultimately eliminate the virus.^4,5

Diagnostic test for COVID-19

Three major diagnostic tests are available to identify SARS-CoV-2: molecular testing, antibody testing, and antigen testing. Both molecular and antigen tests can identify the presence of an active coronavirus infection, and antibody tests can determine if a patient has previously been infected with SARS-CoV-2.¹¹

Due to the body’s immune response, the antibody test was able to diagnose the patient up to 35 days after the onset of COVID-19 symptoms.⁷ The following table shows a comparison of these three different tests.

Many existing test methods, including reverse transcription-polymerase chain reaction (RT-PCR), employ RNA templates for the detection of the SARS-CoV-2 gene, but many of these approaches are inconvenient and time-consuming. ..

Detection of antibodies and antigens of COVID-19 infection is more efficient, and some kits approach instant detection for faster diagnosis.¹¹

Important role of antigens and antibodies in rapid diagnosis of SARS-CoV-2

By August 28, the FDA had approved 194 diagnostic tests for emergency use. These tests employ three different detection methods, including four antigen tests and 40 antibody tests.^4,6,8 Unfortunately, due to the combination of urgent demand and relaxation of FDA guidelines, some of these tests show poor performance.^7,8

One of the major interferences in immunoassay performance is cross-reactivity.Two major proteins used in SARS-CoV-2 Serological tests – spike (S) glycoprotein and nucleocapsid (N) protein – contain immunogenic domains that are conserved in other β-coronavirus strains. Some of them are known to cause colds.²

Therefore, highly specific antibodies and antigen reagents are essential and kit tests should be performed with high purity control antibodies to ensure accuracy while avoiding false results.^9,15

Zhao et al. Utilized the biotin-labeled S1 protein from ACRO Biosystems for the development of the COVID-19 chemiluminescent immunoassay. Rather than investigating immunoglobulin (Ig) G or IgM levels, this test successfully evaluated the antibody as a whole, achieving 93.2% sensitivity and 100% specificity.

The kit was also able to detect SARS-CoV-2 in some patients with undetectable viral RNA levels in the early stages of the disease (within a week). Combined with molecular testing, the kit was able to increase the sensitivity for detecting COVID-19 (p <0.001).^Five

Due to the global impact of COVID-19, as well as protein reagents, these tests need to be rapidly extensible while providing high-throughput analysis. It also needs to be effectively distributed around the world.

In April, scientists based at Polyclinico San Matteo Hospital in Italy were able to develop a fully automated test that could analyze up to 170 samples per hour. This chemiluminescent assay detected SARS-CoV-2 IgG antibodies against the S1 and S2 domains of the S protein and was highly specific.^Ten

ACRO Biosystems provides high quality antigens and antibodies

ACROBiosystems is at the forefront of recombinant protein production and has already developed over 100 products to support research aimed at combating SARS-CoV-2.

These products contain a range of high quality antibodies and antigens, SARS-CoV-2 Serological diagnostic test. Table 1 provides a summary of these products.⁹

table 1. ACRO Biosystems SARS-CoV-2 product.⁹

Hot products

Matched antibody pair for antigen detection:

• 10 pM level super affinity (BLI)
• High sensitivity of 12 pg / mL (ELISA)
• High specificity: no cross-reactivity with other coronaviruses
• It is suitable for various antigen detection methods such as CLIA, ELISA, and GICA.
• High consistency between batches and bulk ordering possible

Antigen for antibody detection:

• Customized prescriptions and bulk orders are possible
• Verified features
• High purity and consistency between batches

These products are scalable and can be distributed globally.⁹

References and references

1. ECDC.eu (2020). COVID-19 Situation Update Worldwide, as of June 28, 2020. https://www.ecdc.europa.eu/en/geographical-distribution-2019-ncov-cases..
2. Welssleder R., et al. (2020). COVID-19 diagnosis according to the situation. Scientific translation medicine.
3. BBC.co.uk. (2020). Coronavirus: The outbreak in Germany has caused a new regional blockade. https://www.bbc.co.uk/news/world-europe-53149762..
4. ACROBiosystems.com (2020). COVID-19 A protein specially designed for the development of serological tests. https://www.acrobiosystems.com/A1126-Specially-Designed-Proteins-for-COVID-19-Serological-Test-Development.html..
5. Zhao J., et al.. (2020). Antigen-antibody response to SARS-CoV-2 in patients with new coronavirus disease in 2019. Clinical infection.
6. ACROBiosystems.com (2020). Is the serological test unreliable? Protein reagents are the key. https://www.acrobiosystems.com/A1127-Serological-tests-are-unreliable-The-protein-reagents-are-the-key.html..
7. Dikes JJ, et al. (2020). Antibody tests to identify current and past infections with SARS-CoV-2. Cochrane database of systematic reviews.
8. ACROBiosystems.com (2020). How does the COVID-19 antibody ELISA test work? https://www.acrobiosystems.com/A1125-How-does-the-COVID-19-antibody-ELISA-test-function.html..
9. ACROBiosystems.com (2020). SARS-CoV-2 related products. https://www.acrobiosystems.com/A1111-2019-nCoV-Proteins.html
10. Younes N., et al. (2020). Challenges in laboratory diagnosis of the novel coronavirus SARS-CoV-2. Virus.
11. FDA.gov (2020). The basics of coronavirus testing. https://www.fda.gov/media/138094/download

About ACRO Biosystems

ACRO Biosystems Is a leading manufacturer of recombinant proteins and other important reagents that support the development of targeted therapeutics. The company employs an application-oriented development strategy with a particular focus on product design, quality control, and solution-based support. Our products and services allow anyone in the field of drug development to have a more intuitive and streamlined process.

To address the coronavirus pandemic, ACRO Biosystems has developed SARS-CoV-2 antigens specifically designed and optimized for serological test kits such as spike-derived antigens S1, RBD, and nucleocapsid proteins. .. Protein has been supplied in large quantities to diagnostic companies.

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