So instead of asking how long a virus can live outside the body, we can ask how long it remains infectious , that is, how long it retains its ability to invade a living cell and cause mischief. That ability depends on how long the extremely complex structure of a virus stays intact. And extremely complex it is. A virus is composed of a complex array of nucleic acids, proteins, glycoproteins proteins with carbohydrates attached , fats and water molecules, all assembled in a three-dimensional network.
If this assembly is disrupted, the virus cannot invade a cell. The picture we so often see of the coronavirus features spikes emerging from a ball. Those spikes contain the proteins the virus uses to attach itself to receptors on cells, which is the first step to invading a cell. Water molecules can also take part in such bonding with the two hydrogens being attracted to oxygen or nitrogen atoms on two amino acids located at different positions on the protein chain, forming a bridge.
Although somewhat too simplistic, a lock and key model can serve as an analogy. We now see that there are at least three ways that a virus can become inactive. In the lytic cycle, the virus attaches to the host cell and injects its DNA. Then fully formed viruses assemble. These viruses break, or lyse, the cell and spread to other cells to continue the cycle.
Like the lytic cycle, in the lysogenic cycle the virus attaches to the host cell and injects its DNA. In humans, viruses can cause many diseases. For example, the flu is caused by the influenza virus. Typically, viruses cause an immune response in the host, and this kills the virus.
However, some viruses are not successfully treated by the immune system, such as human immunodeficiency virus, or HIV. This leads to a more chronic infection that is difficult or impossible to cure; often only the symptoms can be treated. Unlike bacterial infections, antibiotics are ineffective at treating viral infections. Viral infections are best prevented by vaccines, though antiviral drugs can treat some viral infections. Most antiviral drugs work by interfering with viral replication.
Some of these drugs stop DNA synthesis, preventing the virus from replicating. Although viruses can have devastating health consequences, they also have important technological applications.
Viruses are particularly vital to gene therapy. Because some viruses incorporate their DNA into host DNA, they can be genetically modified to carry genes that would benefit the host. Some viruses can even be engineered to reproduce in cancer cells and trigger the immune system to kill those harmful cells.
Although this is still an emerging field of research, it gives viruses the potential to one day do more good than harm. Emerging Infectious Diseases. You may also be interested in. What is social distancing and which measures work best? Read more. How does the coronavirus spread from one person to another? Disinfecting surfaces for coronavirus: Does it reduce infection? Was this helpful? Helpful Not helpful. Thank you for your feedback.
This website is supported by. This website is powered by. The amount of virus that lands on a surface, as well as the temperature and humidity of the environment, also determines how long cold, flu and other viruses stay active outside the body.
It's possible to catch the flu or a cold virus after touching an object that a person with one of these viruses sneezed or coughed on a few moments before. But close contact with a person who has one of these viruses — such as a handshake or breathing in droplets from a cough or sneeze — is the most common way these viruses spread.
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