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A research team in Hungary pinched the coronavirus with a fine needle to measure how much force it could take before popping like a balloon. But it did not.
The native virion of Sars-CoV-2 – a complete virus particle – was only about 80 nanometres wide, and the needle tip was much smaller than that. The tip drove from the top of the virus to the bottom. The virion was squashed, then immediately rebounded as the needle left.
The researchers repeated the drill 100 times and the same viral particle remained almost intact.
It is “surprisingly resilient,” said the team led by Dr Miklos Kellermayer of Semmelweis University in Budapest in a non-peer-reviewed paper posted on biorxiv.org on Thursday.
Scientists from the Semmelweis University in Budapest pinched the coronavirus with a nano needle
The new coronavirus has constantly surprised scientists with its unique structure. For instance, a team from Tsinghua University in Beijing released the most detailed structural reconstruction of the virus in the journal Cell this week with the discovery that the virus could pile a large amount of nucleic acid ribbon that carries genetic data into a very tight envelope without the two becoming entangled.
However, the virus used in this and other previous studies was frozen to obtain a sharp, stable shot for the camera.
Kellermayer’s team captured how the virus behaved when it was alive. They put the viral particles on a tray coated with a biological binding material.
The material could fix the virus in position. Under a laser-emitting atomic force microscope, the scientists played around with the virus with a needle to see how it responded to various stimuli.
A virus usually becomes vulnerable after leaving the host. But according to some studies, Sars-CoV-2 could stay on some everyday surfaces such as cupboards for several days.
How it managed to survive environmental disturbances remained unclear.
The Hungarian team found the viral envelope barely gave any resistance as the needle tip landed on the surface. As the tip went further, the resisting force peaked and then quickly diminished to almost non-existent.
Their experimental data suggested Sars-Cov-2 could be the most physically elastic virus ever known to humans so far, and repeated deformation did not seem to affect the overall structure and the content inside the virus, either.
A 3D medical illustration of the coronavirus
Chinese scientists estimated that Sars-CoV-2 had on its surface 26 spike proteins that could bind with a host cell. Researchers at Cambridge University in Britain gave a similar estimate of 24. A study by researchers in the Max Planck Institute in Germany came up with a count of 40.
Kellermayer said there were 61 spikes on their specimen. This suggested the variability of the viral structure could be greater than thought, they said.
They poked the spike proteins with the needle and found they were swinging rapidly at high frequency. The atomic camera could take more than 300 shots in a second but still only got a motion-blurred image of the spikes.
Such high speed movements could help the virus more easily find and hook onto a host cell, according to the researchers.
A study by French scientists in April found that the virus could replicate in animal cells after being exposed to a temperature of 60 degrees Celsius for an hour. The massive outbreaks in some countries over the northern hemisphere summer also suggested that high temperature did not slow the spread of the pandemic as previously hoped.
Kellermayer and his colleagues heated the viral particle to 90 degrees for 10 minutes and found that “remarkably, their global appearance was only slightly altered”.
Some spikes had come off under the scorching heat, but the overall structure remained intact.
新冠病毒太顽强！弹性强耐高温能自愈，挤压一百次后仍能反弹
匈牙利研究团队日前发表究报告指出，新冠病毒可能是已知最具物理弹性的病毒，它的自愈力很强，而且很耐热，或令它能适应不同的环境。它并没有如研究人员所猜想般，在测试中像气球爆破一样爆开。
该团队在实验时将病毒粒子放在托盘上，上面涂有能固定病毒的生物结合物料。在显微镜下，他们将纳米针头刺进病毒，观察它在刺激下有何反应。
该团队将针头由上而下刺进病毒，发现它会被压扁，在针头被抽走后立即反弹。科研人员重复100次同样动作，病毒仍几乎完整无缺。科研人员形容病毒出奇地有复原能力，即使重复变形、其整体结构、以及病毒内的东西也似乎不受影响，病毒的惯性及自愈特点或令它能适应大量不同的环境。
凯勒迈耶博士及研究人员将病毒粒子加热至摄氏90度，并维持10分钟，竟然发现病毒的整体结构只有少许变化。只是病毒上有一些棘蛋白脱落。病毒的耐热力强，或与它们的气态胶体及表面稳定性有关。
该研究团队的病毒样本有61条棘蛋白，与英国专家估计的24条不同，证明病毒的结构变化比他们想像中大。他们用针头刺病毒的尖刺后，看到它们会快速并高频率地摆动，这或有助病毒寻找并钩住宿主细胞。
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