Of the millions of different viral species identified so far, only about 5, have been characterized in detail. None of them works in precisely the same way. This should be good news for us when it comes to coronaviruses. However, the bad news is that the coronavirus can be quite stable outside of cells because its spikes, protruding like needles from a pincushion, shield it from direct contact, enabling it to survive on surfaces for relatively long periods.
Still, soap or alcohol-based hand sanitizers do a good job of disabling it. But not all coronavirus spikes are alike. Relatively benign coronavirus variants, which at their worst might cause a scratchy throat and sniffles, attach to cells in the upper respiratory tract — the nasal cavities and throat. Stanford is participating in a clinical trial, sponsored by the National Institutes of Health, to see if antibody-rich plasma the cell-free part of blood from recovered COVID patients who no longer need these antibodies can mitigate symptoms in patients with mild illness and prevent its progression from mild to severe.
Monoclonal antibodies are to the antibodies in convalescent plasma what a laser is to an incandescent light bulb. A worry: Viral mutation rates are much higher than bacterial rates, which dwarf those of our sperm and egg cells. Assistant professor of chemical engineering and subcellular-compartment spelunker Monther Abu-Remaileh , PhD, described two key ways the coronavirus breaks into a cell and seeks comfort there, and how it might be possible to bar one of those entry routes with the right kind of drug.
Grease loves grease. The viral envelope and cell membrane fuse, and the viral contents dump into the cell. The other way is more complicated. To visualize this, imagine yourself with a wad of bubble gum in your mouth, blowing an internal bubble by inhaling, and then swallowing it. Enclosed in this endosome is the viral particle that set the process in motion. Its mission is to become another entity called a lysosome, or to fuse with an existing lysosome. For this, they need an acidic environment, generated by protein pumps on their surface membranes that force protons into these vesicles.
The viral genome gets squirted out into the greater expanse of the cell. There, the viral genome will find and commandeer the raw materials and molecular machinery required to carry out its genetic instructions. That machinery will furiously crank out viral proteins — including the customized polymerase SARS-CoV-2 needs to replicate its own genome.
A pair of closely related drugs, chloroquine and hydroxychloroquine, have gotten tons of press but, so far, mostly disappointing results in clinical trials for treating COVID Some researchers advocate using hydroxychloroquine, with the caveat that use should be early in the course of the disease.
In a lab dish, these drugs diffuse into cells, where they diminish acidity in endosomes and prevent it from building up in lysosomes. The virus remains locked in a prison of its own device. But only further clinical trials will tell how much that matters. SARS-CoV-2 has entered the cell, either by fusion or by riding in like a Lilliputian aquanaut, stealthily stowed inside an endosome.
It must replicate itself in entirety and in bulk, with each copy constituting the potential seed of a new viral particle. To do both things, the virus needs a special kind of polymerase. Every living cell, including each of ours, uses polymerases to copy its DNA-based genome and to transcribe its contents the genes into RNA-based instructions that ribosomes can read.
Studying the shapes of their proteins , for example, has shown that viruses share certain protein structures — and therefore properties — with organisms from all branches of the tree of life. There are variations to this theory, such as the idea that viruses might have come from circular pieces of DNA called plasmids in archaeans , and that giant viruses might be the remnants of extinct domains of life.
Ultimately, science may never agree on whether viruses are alive or not. The answer is not as straightforward as you may think. Articles Videos. This won't be the last pandemic. Where will the next one come from? Viruses meet their mismatch Animal DNA is full of viral invaders and now we've caught them at it Should deadly viruses be used to treat cystic fibrosis? Ultraviolet light, particularly short-wavelength UV-C , is energetic enough to break chemical bonds and has been shown to alter the structure of nucleic acids.
Put all of this together and we can see why the viability of a virus to cause an infection wanes with time. That time, though, depends on several factors. The cleanliness of the surface is important. Viral particles can be embedded in grease, protecting them from outside agents.
The composition of the surface can also play a role. Copper, for example, releases copper ions that have antiviral activity. Paper has residues of the chemicals used in pulping that can inactivate viruses. Steel and plastic seem to be more hospitable, but even here survival time is only a couple of days.
Obviously, the viability of viruses can be reduced with disinfectants like soap, alcohol, sodium hypochlorite bleach , hydrogen peroxide, quaternary ammonium compounds alkyldimethylbenzyl ammonium chloride all of which in some way disrupt the chemical bonds that maintain the shape of the virus particles.
Like everything else in life, the viability of virions is a function of molecular structure. It is a matter of chemistry. Leave a comment! Enter your keywords.
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