Virus

Today I’m going to talk about: Virus (life science)

Virus (life science), infectious agent found in virtually all life
forms, including humans, animals, plants, fungi, and bacteria. Viruses
consist of genetic material DNA or RNA but not both surrounded by a
protective coating of protein, called a capsid, with or without an outer
lipid envelope. Viruses are between 20 and 100 times smaller than bacteria
and hence are too small to be seen by light microscopy. Viruses are not
considered free-living, since they cannot reproduce outside of a living
cell; thhey have evolved to transmit their genetic information from one cell
to another for the purpose of replication. Viral replication is often
carried out at the expense of the host: Diseases such as herpes, rabies,
influenza, some cancers, poliomyelitis, and yellow fever are of viral
origin. Of the estimated 1000 to 1500 types of viruses, approximately 250
cause disease in humans (over 100 of which cause the common cold), and 100
infect other animals. Because viruses are programmed to carry genetic
information into cells, they have been used to replace ddefective cellular
genes. Viruses are also being altered by genetic engineering to kill
selected cell populations, such as tumor cells. The use of genetically
engineered viruses for medical intervention is a relatively new field, and
none of these therapies is widely available.

Because viral processes so

o closely resemble normal cellular processes,
abundant information about cell biology and genetics has come from studying
viruses. Basic scientists and medical researchers at university and
hospital laboratories are working to understand viral mechanisms of action
and are searching for new and better ways to treat viral illnesses. Many
pharmaceutical and biotechnology companies are actively pursuing effective
antiviral therapies. Viruses can also serve as tools. Because they are
efficient factories for the production of viral proteins, viruses have been
harnessed to produce a wide variety of proteins for industrial and research
purposes. A new area of endeavor is the use of viruses for gene therapy.
Because viruses are programmed to carry genetic information into cells,
they have been used to replace defective cellular genes. Viruses are also
being altered by genetic engineering tto kill selected cell populations,
such as tumor cells. The use of genetically engineered viruses for medical
intervention is a relatively new field, and none of these therapies is
widely available. However, this is a fast-growing area of research, and
many clinical trials are now in progress. The use of genetically engineered
viruses extends beyond the medical field. Recombinant insect viruses have
agricultural applications and are currently being tested in field trials
for their effectiveness as pesticides.

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