This Image Shows SARS-CoV-2 Conquering A Human Lung Cell

Images of SARS-CoV-2 infecting a human cell, taken with a scanning electron microscope.The New England Journal of Medicine ©2020.

You're looking at SARS-CoV-2, the coronavirus responsible for Covid-19 that’s no doubt not only ruined your 2020, but changed the world. 

Reported in the New England Journal of Medicine, scientists at the University of North Carolina School of Medicine have released striking images of the SARS-CoV-2 virus infecting bronchial cells. You’d typically find these cells in the main passageway into the lungs, but here they were in a petri-dish for the purpose of imaging. 

"These images of SARS-CoV-2 infected cultures showing ciliated cells jam-packed with viruses releasing large clumps of virus particles make a strong case for the use of masks by infected and uninfected individuals to limit SARS-CoV-2 transmission," Camille Ehre, an assistant professor at the University of North Carolina School of Medicine's Marsico Lung Institute who captured the images, told IFLScience.

The coronaviruses in question are the hundreds of tiny fuzzy dots (seen in red below) that are covering the stand-like cellia (turquoise) on the cell. Viruses are absolutely minuscule and SARS-CoV-2 is no different, measuring between 50 to 200 nanometres in diameter. For context, human red blood cells are about 7,000 nanometers across. This means the viruses are too small to be seen with a light microscope and only observable with an electron microscope.

A colorized image of SARS-CoV-2. Ehre Lab/UNC School of Medicine

As you can see from the image, there is an extremely high number of virions (an entire virus particle) produced and released by a cell in the human respiratory systems. This is effectively how the pathogens can invade and overwhelm a human body; using the host cells’ own machinery to produce copies of itself, which then flood out and spread to new cells. 

"The most striking observation was the astonishing number of virions produced by a single infected cell. Some of these infected cells were so engorged with viruses that they rounded up and detached from the epithelium, giving the impression that they were about to burst and creating an ideal vehicle for these virions to infect either the distal lung by aspiration or come out of the nose to infect the next person," Ehre said.

You can also just about see some of the structure of SARS-CoV-2. A virus consists of little more than a single strand of RNA (a bit like half of the ladder-shaped DNA) covered in a lipid bilayer and protein spikes. Coronaviruses take their name from their protein spikes, which are said to look like a crown, translated as “corona” in Latin. These spikes, which give the virions their fuzzy outline in this image, are effectively the key used by the pathogen to enter the host cell.

"SARS-CoV-2 viruses appeared to be released in large clumps or bundles," added Ehre. "A huge viral load is therefore available to spread within an infected individual and infect the olfactory epithelium, explaining the common symptom of loss of smell, and also infect the salivary glands, which would explain the symptom of dry mouth. The worst is when viruses go to the lungs and produce pneumonia that causes shortness of breath and ultimately can lead to death."

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