- Are there many different types of coronaviruses?
- Does Coronavirus change easily?
- Are there particular regions more or less prone to mutation?
These are the questions asked by two Italian researchers, Federico Giorgi and Carmine Ceraolo, in a study that was recently published in the Journal of Medical Virology.
Comparison of Coronavirus strains
As a basis for their study, the two Italian researchers took all 56 different Coronaviruses extracted from Coronavirus infected patients that have so far been isolated and sequenced since the outbreak: 43 from China, 2 from Thailand, 5 from the USA, 2 from Italy, 2 from France, 1 from Germany, and 1 from Australia.
The results of this analysis of a large number of data tell us that all these genomes are very similar to each other even if they’re from different regions; so much so that their code sequences overlap more than 99%.
The resemblance to the bat virus
This discovery made it possible to conduct an analysis of the Coronavirus genome with that of the other animal Coronaviruses. This was important to understand which it most closely resembles, and therefore probably which animal virus it is related to. The human Coronavirus genome shares 96% of the bat coronavirus sequence. On the other hand, it has a similarity of only 80% when compared to the SARS virus. Therefore, it is better to confirm what has already been hypothesized regarding the origin of the virus, that it developed as a variant of the bat virus capable of affecting the human species.
The fact that the virus is not very heterogeneous and not very mutable authorizes us to be rather confident that the potential therapies that will be used will be effective against all or almost all viral strains.
A point of high variability
The Bologna study also identified a single point of high variability of virus proteins. In particular, there is a virus-type protein in which the change of a single amino acid (from leucine to serine) can change the structure of the protein itself. Currently, two subtypes of this protein have been identified but a model that tries to understand which structural modifications of the protein correspond to these modifications of the genomic sequence is not yet available.
This study is of great interest because it has made us understand that currently the viral strains, at least all those identified so far, are substantially similar to each other and there are no extensive variabilities that can make us fear high mutagenicity. This is important because any future therapies and vaccines, given the substantial uniformity of the virus, should be effective on a large scale rather than, as can sometimes happen, only on some viral strains.
Marco De Nardin M.D.