COVID-19, which first surfaced in Wuhan, China in December 2019, roams the world relentlessly. The scale of the epidemic has caused chaos and led to the World Health Organization declare a pandemic in March 2020.
Understanding the virus is the concern of scientists trying to unravel its mysteries as a first step in finding ways to stop the spread of the disease and to find a vaccine. Every day, scientists discover new things about SARS-CoV-2, the virus behind the rapidly spreading disease COVID-19.
One area of research is the relationship with other coronaviruses. For example, it has been identified as part of the same family of coronaviruses that caused it Severe acute respiratory syndrome (SARS) and Middle East Respiratory Syndrome (MERS). SARS was first identified in 2002. It caused serious respiratory illnesses that were fatal in about 10% of cases. MERS, on the other hand, came from the Middle East and caused death, although less contagious, in about 37% of cases.
Scientists to investigate SARS-CoV-2 has found that the structure is very similar to the SARS-CoV. But there are also a number of clear differences. For example, one of the most surprising differ from COVID-19 is the rapid spread around the world.
Closing the gap in understanding these differences and similarities is what stands between scientists and a solution to the rapidly spreading disease. An essential line of research on how the body can fight and overcome the infection is how blood types – and the associated antibodies – can affect the immune response.
Similarities and differences
SARS-Cov-2 is round in shape and has a number of proteins called spikes on the surface. These peaks attach to the same human cell receptor (angiotensin converting enzyme 2) as the SARS-CoV. This information is important because it suggests that the virus uses the same mechanism to cause the viral genes to enter, replicate, and infect other cells. Scientists can use this to develop drugs that inhibit the binding of the spike protein, thereby slowing the virus's ability to replicate.
Another similarity is the structure of the spike protein called NSP15. Scientists from a number of universities in the US have studied the structure of this protein and found it to be so 89% similar to the NSP15 protein in SARS-CoV.
Like COVID-19, SARS was highly contagious. But there was one quirk: Not everyone exposed to people who were already infected developed the disease.
An area of Research whether blood groups and naturally occurring antibodies may affect the spread or severity of infection.
The distribution of the four major blood groups (A, B, AB and O) varies between population groups and geographic regions due to natural selection, the environment and disease. Until recently, blood types were widely known for their role in blood transfusion. If patients received incompatible blood, potent naturally occurring anti-A or anti-B antibodies could cause a blood transfusion reaction.
But research has shown that blood types can also play a role in infection and how the body's immune system responds. One theory is that blood group antigens can act as binding receptors that allow viruses or bacteria to attach and enter the body's cells.
An example of this is the norovirus causing severe vomiting and diarrhea. This virus can bind to ABO antigens on mucosal surfaces of the gut, and once this happens it can enter the host cell and then replicate. On the other hand, anti-A and anti-B antibodies can be part of the body's natural defenses and can limit or even prevent infection.
What about coronaviruses?
Doctors in a hospital in Hong Kong studied this phenomenon and reported that individuals who were blood group O were found to be less prone to SARS-CoV than those who were group A, B or AB. Investigators shown that the virus could express antigens on the surface, similar to those in the ABH blood group. She also reported that naturally occurring anti-A antibodies could inhibit or even block the binding of the virus to the host cell.
This led to the theory that group O individuals, who have both anti-A and anti-B antibodies, may have some protection against infection.
The fact that blood groups and their associated antibodies influence the immune response is one of the lines of research into how the body can fight and overcome the infection. How this happens in COVID-19 requires even more research to build on the work that has already been done.
Another discovery is that the SARS-CoV-2 spike protein is unique and attaches 10-20 times more to human cells. This could explain the increased and faster spread across populations.
The structure of these unique spike proteins is extremely important because they will form the basis for the development of a vaccine.
The ABO blood type has evolved over thousands of years in response to disease. The antigens and antibodies that make up this system interact with cells of the immune system and can affect the way they respond. As we learn more about SARS-CoV-2, the role of any blood types may become clearer.
Updated Date: 26 March 2020 09:22:44 IST