Researchers have discovered the enzyme used by SARS-CoV-2 to defeat the body’s innate immune response, which explains its greater contagiousness, compared to other coronaviruses.
- This is due to the effectiveness of an enzyme which allows it to eliminate the ISG15 marker which allows the innate immune system to identify the virus and fight it.
- SARS-CoV, MERS-CoV and SARS-CoV-2 are three coronaviruses causing deadly epidemics.
- Researchers have discovered why SARS-CoV-2 is more contagious than the other two: the virus neutralizes the innate immune response more effectively.
In the 21st century, three emerging coronaviruses are causing serious human respiratory diseases and deadly epidemics according to the National Institute of Health and Medical Research (Inserm): SARS-CoV in 2003, MERS-CoV in 2012 and SARS-CoV-2 in 2020.
SARS-CoV-2 more contagious
Researchers from Kobe Universityin Japan, wanted to understand why SARS-CoV-2 was more contagious than its predecessors. In their research, they discovered that SARS-CoV-2 has an enzyme capable of defeating the innate immune system response.
In humans, there are two types of defense mechanisms: innate immunity and adaptive immunity. The first is constituted, according to the Quebec Ministry of Healthan external line of defense (anything that prevents pathogens from entering the body) and an internal line of defense (cells and proteins that fight against the proliferation of infectious agents once they are in the organism). On the other hand, adaptive immunity strengthens little by little, with exposure to pathogens. This is what vaccination is based on.
“THE [SARS-CoV-2] is so infectious that we wondered what mechanisms the virus used to evade the innate immune system so effectively”, indicates SHOJI Ikuo, one of the authors of the study, in a press release.
An enzyme that hijacks the immune system
In previous work, scientists discovered a molecular marker called ISG15 that allows the innate immune system to identify the virus and fight it. But, in this new study published in the journal Journal of Virologyresearchers discovered that SARS-CoV-2 had an enzyme that removed the ISG15 marker.
SARS-CoV and MERS-CoV also have an enzyme that eliminates the ISG15 marker, but this enzyme is much less effective than that of SARS-CoV-2. It is therefore for this reason, the effectiveness of the enzyme, that SARS-CoV-2 is more contagious.
“These results suggest that the new coronavirus is simply more effective at evading this aspect of the innate immune system’s defense mechanism, which explains why it is so infectious.underlines SHOJI Ikuo. We may be able to develop new antiviral drugs if we can inhibit the function of the enzyme”.
