Targeting the spike protein

The vaccine is aimed at the part of the COVID spike (S) protein that is resistant to mutations and is common for almost all types of coronaviruses.

During the experiment, the vaccine was used to vaccinate pigs infected by two types of coronaviruses — COVID-19 and porcine epidemic diarrhea virus (PEDV). These two coronaviruses are related, but they are distant relatives. The researchers have assumed that if the vaccine against COVID-19 can also protect a pig from PEDV, it will also be capable of protecting a wide range of various coronavirus strains.

The vaccine has not prevented infection but has prevented a severe form of the disease. It has also made the pigs' immune system develop a stronger response to future infection.

For the moment, the researchers will have to find an optimal dose, the best route of administering the vaccine, and an optimal dosage schedule. They also plan to experiment with other substances that can be added to further increase the immune response.

Different vaccine approaches

Modern vaccines work by tricking human cells into producing incomplete versions of the COVID spike (S) protein. The immune system reacts to it by building a defense against future attacks. The Pfizer and Moderna (mRNA) vaccines do this by entering genetic information directly into the cells through the messenger RNA. The Johnson & Johnson vaccine uses modified adenovirus for harmless infection of the cells. Both of these types of vaccines get into the cells and make them develop vaccine antigens.

The experimental vaccine uses another approach. The researchers genetically engineered E. coli (Escherichia coli) bacteria, destroying those of their components that cause disorders and adding a coronavirus target protein. After that, the bacteria are killed and introduced into the human body, where the immune system identifies them as an aggressor and develops a response.

In this case, the immune response is caused by bacteria instead of what is produced by body cells. The bacteria-based vaccines are referred to as inactivated (dead) whole-cell vaccines. They have been known for a hundred years and need only a cold chain for transportation. This requirement makes their mass application much simpler than, for example, mRNA vaccines requiring a deep freeze.

Cheaper means better

The mRNA vaccines used today against COVID-19 cost around $10 per dose, which can be too expensive for developing countries. However, bacteria-based vaccines can be produced on a large scale at very low prices. In the past, a South Korean company produced 6 million doses of cholera vaccine in one year at less than $1 per dose. If the developers of the universal coronavirus vaccines succeed, the price would be approximately the same.

Source: https://medicalxpress.com/news/2021-04-cheap-universal-coronavirus-vaccine.htm

02 July 2021