|
A
virus is a tiny, sub-microscopic particle that contains genetic
information. Most experts consider them to be non-living, because they don't
display most of the characteristics of living beings. Viruses only have the
ability to reproduce and grow when they are infecting host cells. The rest of
the time they are in a sort of dormant state, called a capsid. There are over
five thousand different forms of known viruses.
The
appearance of viruses varies widely.
Bacteriophages , which attack bacteria, almost look like little spaceships.
Some other viruses look round with little spikes sticking out, or like a piece
of tangled string, or like a thin stick. Their
structure is relatively simple in that they only have two or three
components. All viruses contain genetic information, which is surrounded by a
protein coat. Some also have a fat membrane.
Viruses have the ability to
infect
a wide variety of living organisms, including animals, bacteria, plants, and
archaea. They are known for causing many diseases in humans. Viruses are
responsible for smallpox, HIV, influenza, the cold, sexually transmitted
diseases, and many other diseases, although a lot of viruses exist without
causing any problems to the host.
Humans and other vertebrate animals have
immune systems that can protect against viral infections. The immune system
creates antibodies which fight against viruses and try to prevent them from
doing harm, but it often takes time for the body to learn how to defend itself
against a strain it hasn't encountered before. Sometimes, as with HIV, the
immune system is incapable of neutralizing the virus.
The
evolution of viruses makes it more difficult to defend against them.
Because viruses can reproduce many generations in a short amount of time, their
genetics can change quickly. This is why there are new and different strains of
the flu every year. They tend to become more dangerous over time, because the
viral particles that are harder to fight off are more likely to reproduce and
infect another organism. Medications like antibiotics accelerate these genetic
changes and, over time, lead to “superviruses.”
Home -
Genital Warts -
Related Articles
|
