Vaccines work by exposing the body to molecules of the target pathogen to trigger an immune response. But the method of exposure varies.

Against SARS-CoV-2, there are so far four types of vaccine platforms: virus-based, vector-based, nucleic acid-based and protein-based.

On Monday, December 27, 2021, the United Arab Emirates approved CNBG Sinopharm’s COVID-19 vaccine using the recombinant protein subunit platform. It would be used as a booster for people previously inoculated with two doses of Sinopharm’s inactive jab, according to the United Arab Emirates Department of Health and Prevention (MoHAP). Here is the truth about this class of vaccines:

In a nutshell, a protein subunit vaccine exploits tiny particles containing several artificial spikes grown in cell cultures and then uses them as a vaccine against an illicit immune response in the recipient’s body. Sinopharm’s new recombinant protein vaccine uses the Spike (S) protein that surrounds the SARS-CoV-2 virus. This helps the body to identify the virus and then fight it off if exposed. The technology makes it possible to avoid several variations.

It is generally made by recombinant synthesis of protein “antigens” (molecules that trigger an immune response), as well as by methods of protein isolation and purification, Nature Explain. “Recombinant” means to use genetic engineering to produce the new vaccine. This is usually done by inserting genetic material of protein S into the genetic material of another organism (yeast, bacteria).

This is achieved by culturing large amounts of the pathogen (disease causing agent i.e. virus / bacteria, in this case SARS-CoV-2). The genetically modified organism produces the S protein, which is then extracted, purified and introduced as an active ingredient in the vaccine.

Today, the best-known example of this vaccine development strategy are the subunit influenza vaccines.

It is a proven vaccine platform. It is also quite common. Currently, the WHO lists at least about 70 candidate subunit protein vaccines against SARS-CoV-2.

Each exploits a different immunogen – primarily various forms of the entire Spike (S) protein or its receptor binding domain (RBD), the region of the S protein that mediates viral binding to the ACE2 receptor of target host cells.

Upon binding to the ACE2 receptor of the host cell, the pre-fusion conformation of protein S undergoes an extensive conformational change to a highly stable post-fusion conformation which allows fusion between the viral particle and the membranes of the host cell.

Write for Nature, Nikolaos C. Kyriakidis of One Health Research Group, Universidad de Las Américas (UDLA), Quito, Ecuador, and colleagues explained, “As a general rule, pre-fusion stabilized viral glycoproteins are generally more immunogenic, making them more attractive vaccine targets. “

The first forms of protein subunit vaccines developed aimed to harness the ability of protein antigens to trigger immunoglobulins (aka antibodies). In the 1960s, one of the earliest examples of an “acellular vaccine” was the protective anthrax antigen.

The technique, developed in the 1960s, gained ground in the 1990s with the explosion of genetic engineering, allowing the cloning and acceleration of the production of antigens in vitro (in a test tube, box or elsewhere outside of a living organism).

This led to the production of large amounts of the hepatitis B surface antigen in yeast cells – a breakthrough that led to the production of the hepatitis B vaccine.

An “adjuvant” (enhancement of efficacy / potency) is usually added to elicit a robust immune response.

So far, the development of a high-speed COVID vaccine has relied on inactivated virus (Sinopharm, Sinovac), nucleic acid (Pfizer, Moderna mRNA) or vectors (AstraZeneca, Sputnik V) strategies. Today, there are at least 10 other PS-based vaccines approved in at least one state / territory:

1. Anhui Zhifei Longcom ZF2001 (approved in [3]: China, Indonesia, Uzbekistan)

2. Novavax NVX-CoV2373 (approved in [30]: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Liechtenstein, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal , Romania, Slovakia, Slovenia, Spain and Sweden)

3. Instituto Finlay de Vacunas Cuba: Soberana Plus (approved in [1]: Cuba)

4. Instituto Finlay de Vacunas Cuba: Soberana 02 (approved in [4]: Cuba, Iran, Nicaragua, Venezuela)

5. Razi Vaccine and Serum Research Institute: Razi Cov Pars (approved in [1]: Iran)

6. Serum Institute of India: COVOVAX / Novavax formulation (approved in [2]: Indonesia, Philippines)

7. FBRI: EpiVacCorona (approved in [2]): Russian Federation, Turkmenistan)

8. Center for Genetic Engineering and Biotechnology (CIGB): CIGB-66 (approved in [4]: Cuba, Nicaragua, Venezuela, VietNam)

9. Vaxine / CinnaGen Co .: COVAX-19 (approved in [1]: Iran)

10. Medigen: MVC-COV1901 (approved in [1]: Taiwan)

Protein subunit vaccines offer a number of advantages:

They are specifically selected for their ability to stimulate immune cells, according to Gavi, the global vaccine alliance. These fragments are incapable of causing disease – as such, subunit vaccines are considered inherently safe.

Another big advantage is the logistics: vaccines based on protein subunits do not need supercooling, especially compared to mRNA injections.

Rather than injecting a whole pathogen (disease causing virus / bacteria) to trigger an immune response, PS vaccines – also known as “acellular vaccines” – contain purified pieces of it.

Protein subunit vaccines are already widely used (i.e. hepatitis B vaccine and acellular pertussis). In terms of manufacturing, a PS vaccine is based on a factory-grown protein, which does not require a live (attenuated) or inactivated virus. Attenuated or inactivated vaccines must first grow the virus in huge quantities in stainless steel containers located inside a highly biosecure facility. in vaccine vials.

PS vaccines are much easier to produce than attenuated or inactivated virus vaccines because facilities with high biosafety levels are not required. However, they must be produced according to the regulations of Current Good Manufacturing Practices (CGMP). This could potentially change the cost equation as well as the distribution.

In theory, this could make COVID vaccines more accessible to poor countries. Currently, only 6% of Africa’s 1.216 billion people have been fully vaccinated against COVID-19 so far, the lowest rate among the world’s 7 continents.

A damper : He frequently raises the need to increase booster doses and optimize the added “adjuvant” to achieve stronger and longer lasting immunization.

No. Laboratory (animal) testing is done before clinical testing (human testing). On April 10, 2021, CNBG obtained regulatory approval for the human testing stage in China for its PS vaccine.

A month earlier, on March 17, 2021, the Recombinant Protein Subunit Vaccine from the Institute of Microbiology of the Chinese Academy of Sciences against COVID-19 was approved by the Beijing government for use in emergency. It was developed by the institute and Anhui Zhifei Longcom Biopharmaceutical, and is the first vaccine using the RPS technique approved by the country for emergency use against COVID-19.

In contrast, Sinopharm’s BBIBP-CorV (Vero cells) has been approved in 80 countries (including the United Arab Emirates); The inactivated vaccine (Vero cells) from Sinopharms (Wuhan) has been approved in 2 countries: China and the Philippines.