What makes them, including the coronavirus, so tricky to cure? Part of the problem is the nature of viruses themselves. They exist like freeloading zombies — not quite dead, yet certainly not alive. The odd makeup of these infectious agents is part of what makes them difficult to defeat. Compared to other pathogens, such as bacteria, viruses are minuscule.
And because they have none of the hallmarks of living things — a metabolism or the ability to reproduce on their own, for example — they are harder to target with drugs. Full coverage of the coronavirus outbreak. Antibiotics, which are used to fight bacterial infections, attack the bacteria's cell walls, block protein production and stop bacteria from reproducing.
But they aren't effective against viral infections, because viruses don't carry out any of those processes on their own. Rather, viruses need to invade and take over host cells to replicate.
But a virus can't break into just any cell in the body. What makes the process even more complicated is that viruses don't just infect humans; they can infect basically any organism—from bacteria to horses; seaweed to people.
Still, scientists have been able to piece together some viral histories, based on the fact that the genes of many viruses—such as those that cause herpes and mono—seem to share some properties with cells' own genes. This could suggest that they started as big bits of cellular DNA and then became independent—or that these viruses came along very early in evolution, and some of their DNA stuck around in cells' genomes. The fact that some viruses that infect humans share structural features with viruses that infect bacteria could mean that all of these viruses have a common origin, dating back several billion years.
This highlights another problem with tracing virus origins: most modern viruses seem to be a patchwork of bits that come from different sources—a sort of "mix and match" approach to building an organism. The fact that viruses like the deadly Ebola and Marburg viruses, as well as the distantly related viruses that cause measles and rabies, are only found in a limited number of species suggests that those viruses are relatively new—after all, those organisms came along somewhat recently in evolutionary time.
Many of these "new" viruses likely originated in insects many million years ago and at some point in evolution developed the ability to infect other species—probably as insects interacted with or fed from them. HIV, which is thought to have first emerged in humans in the s, is another kind of virus, known as a retrovirus. A virus that is outside of a host cell is known as a virion.
Not only are viruses microscopic, they are smaller than many other microbes, such as bacteria. Most viruses are only 20— nanometers in diameter, whereas human egg cells, for example, are about micrometers in diameter, and the E. Viruses are so small that they are best viewed using an electron microscope , which is how they were first visualized in the s. Viruses generally come in two forms: rods or spheres. However, bacteriophages viruses that infect bacteria have a unique shape, with a geometric head and filamentous tail fibers.
No matter the shape, all viruses consist of genetic material DNA or RNA and have an outer protein shell, known as a capsid. There are two processes used by viruses to replicate: the lytic cycle and lysogenic cycle. Some viruses reproduce using both methods, while others only use the lytic cycle.
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.
There are many similarities between these viruses. However, there are also key differences. Several new strains of the coronavirus have been identified. These variants may spread faster and some may also impact immunity and vaccine…. Discover symptoms, risk factors, tips to prevent contracting and transmitting it, and more. If you feel like your mental health significantly improved after your first dose of a COVID vaccine, you're not alone.
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