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; they 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, tthey have been used to replace defective 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 ttherapies is widely available.

Because viral processes so 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 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. 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.