Viruses are like stealthy dance partners, constantly changing their moves to outsmart our immune system. Much like a living organism, viruses evolve over time. Even when our immune system learns the dance routine and creates antibodies to fight them off, some viruses manage to switch things up. This ability helps them keep infecting living organisms. But how do they do it?
Using the power of artificial intelligence and mathematical modelling, a group of researchers from Nagoya University unravelled the dance steps of the SARS-CoV-2 virus, responsible for Covid-19. Their findings, recently published in Nature Communications, revealed a fascinating connection between human behaviour and the evolution of Covid-19 strains.
The research team, led by Professor Shingo Iwami, delved into the impact of lockdowns and isolation measures on the virus’ evolution. As we adapted our behaviour to control outbreaks, the virus responded by becoming more transmissible earlier in its life cycle. The study identified a five-fold increase in the maximum viral load as the virus evolved from the Wuhan to the Delta strain, emphasising the intricate relationship between human actions and virus evolution.
Understanding this evolutionary tango is crucial for developing adaptive treatments and interventions. Viruses, like skilled dancers, must balance their moves. Increasing the maximum viral load can be advantageous for transmission, but too much might make individuals too sick to keep the dance going.
Moreover, the researchers discovered intriguing trends using mathematical modelling with an artificial intelligence component to investigate previously published clinical data. The SARS-CoV-2 variants most successful at spreading exhibited an earlier and higher peak in viral load. However, as the virus evolved from the pre-Alpha to the Delta variants, it had a shorter duration of infection. The decreased incubation period and the increased proportion of asymptomatic infections recorded as the virus mutated also affected virus evolution.
The results showed a clear difference. As the virus evolved from the Wuhan strain to the Delta strain, they found a five-fold increase in the maximum viral load and a 1.5-fold increase in the number of days before the viral load peaked.
Iwami and his colleagues suggest that human behavioural changes in response to the virus, designed to limit transmission, were increasing the selection pressure on the virus. This caused SARS-CoV-2 to be transmitted mainly during the asymptomatic and pre-symptomatic periods, which occur earlier in its infectious cycle.
In the final act of this virus story, it turns out we unintentionally influenced how the Covid-19 virus does its dance. Imagine it like a unique dance routine choreographed by us humans. We tried to outsmart the virus with things like lockdowns, but guess what? The virus had its own plans. It changed its moves, preferring to spread when people didn’t show symptoms or were just starting to feel unwell.
So, in our attempt to control the dance floor, we sort of made the virus change its steps. It’s like we accidentally gave it a nudge to do a different dance routine. Who would have thought viruses could be so unpredictable? Next time you’re thinking about how we’re all part of this global dance, remember – our moves might be more influential than we realise!