Along with the emergence of the highly infectious delta variant, Japan saw a massive rise in cases, reaching its largest wave yet with no less than 26,000 positive tests every day.
This was, shockingly and concerningly enough, four times the number of cases during the wave before it.
But just as quickly as it peaked, it also fell once more, with seemingly no explanation!
Cases are now at around 140 a day, which is very curious since the rest of the world is struggling more than ever because of the delta variant.
Now, it finally appears that we may have an answer as to why this happened.
According to researchers from Japan’s National Institute of Genetics, the delta variant might have mutated into something else within the country – a new version that can only fail and lead to its own extinction.
As per the Japan Times, Ituro Inoue and other members of the team are convinced the virus has gained a mutation in its error-correcting protein that allows for genetic errors to gather to the point that it cannot replicate anymore.
This is not the first time that a virus self-destructs as a result of its rapid evolution but it still is a phenomenon very little documented as well as a lucky situation for the country of Japan.
During an interview, Inoue told The Japan Times that “We were literally shocked to see the findings. The delta variant in Japan was highly transmissible and keeping other variants out. But as the mutations piled up, we believe it eventually became a faulty virus and it was unable to make copies of itself. Considering that the cases haven’t been increasing, we think that at some point during such mutations it headed straight toward its natural extinction.”
It all started when the scientists looked into the genomic profiles of the Delta variant and then compared them to the Alpha variants.
They expected that the Delta variant would be really complex, featuring many branches growing from the original strain.
But what they discovered instead was that it only had two main groups and then halted abruptly.
Basically, what this means is that the Delta variant is no longer mutating and creating new sublineages – at least not in Japan!
They went on to delve even deeper into this and examined the nsp14, a viral protein that has been proven to be a proofreading enzyme in RNA viruses before.
More precisely, what this protein does is scan the new genetic material every time the virus’ genetic code replicates, to make sure that there are no errors forming.
After all, mutations in proofreading enzymes are a disaster in any organism, even those who don’t often replicate, let alone in those who tend to replicate into thousands of virions bursting from the host cell in just about ten hours!
The researchers also found a number of genetic changes within nsp14, known as A394V, and they seem to lead to a crippled virus, no longer able to replicate.
This new research seems to finally explain the reason why the Delta variant simply disappeared from Japan in only a couple of months.
While this theory is intriguing and a step forward in understanding the virus, there is still a thing it does not quite explain – why would the crippled virus outcompete the dominant strain?
There could be other explanations as well! After all, the delta variant may have been eradicated there thanks to Japan being one of the most vaccinated countries.
Furthermore, Japanese citizens are especially careful to wear their masks which would lead to outbreaks in highly populated areas getting under control much faster.