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

Virus (life science), infectious agent found in virtually all lifeforms, including humans, animals, plants, fungi, and bacteria. Virusesconsist of genetic material DNA or RNA but not both surrounded by aprotective coating of protein, called a capsid, with or without an outerlipid envelope. Viruses are between 20 and 100 times smaller than bacteriaand hence are too small to be seen by light microscopy. Viruses are notconsidered free-living, since they cannot reproduce outside of a livingcell; they have evolved to transmit their genetic information from one cellto another for the purpose of replication. Viral replication is oftencarried out at the expense of the host: Diseases such as herpes, rabies,influenza, some cancers, poliomyelitis, and yellow fever are of viralorigin. Of the estimated 1000 to 1500 types of viruses, approximately 250cause disease in humans (over 100 of which cause the common cold), and 100infect other animals. Because viruses are programmed to carry geneticinformation into cells, they have been used to replace defective cellulargenes. Viruses are also being altered by genetic engineering to killselected cell populations, such as tumor cells. The use of geneticallyengineered viruses for medical intervention is a relatively new field, andnone of these therapies is widely available. Because viral processes so closely resemble normal cellular processes,abundant information about cell biology and genetics has come from studyingviruses. Basic scientists and medical researchers at university andhospital laboratories are working to understand viral mechanisms of actionand are searching for new and better ways to treat viral illnesses. Manypharmaceutical and biotechnology companies are actively pursuing effectiveantiviral therapies. Viruses can also serve as tools. Because they areefficient factories for the production of viral proteins, viruses have beenharnessed 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 alsobeing altered by genetic engineering to kill selected cell populations,such as tumor cells. The use of genetically engineered viruses for medicalintervention is a relatively new field, and none of these therapies iswidely available. However, this is a fast-growing area of research, andmany clinical trials are now in progress. The use of genetically engineeredviruses extends beyond the medical field. Recombinant insect viruses haveagricultural applications and are currently being tested in field trialsfor their effectiveness as pesticides.