Business

France: Amazon back in business after virus deal with unions

Amazon is gradually reopening its warehouses in France after working out virus safety measures with unions, in an effort to end weeks of legal troubles that had sharply curtailed the company's French business and drawn worldwide ...

Ford burns up billions of dollars in 1Q, posts $2B net loss

The coronavirus crisis is forcing Ford Motor Co. to burn through cash at an alarming rate, but its chief financial officer says there's enough money to make it through the year —even if U.S. factories aren't restarted.

Internet

Facebook to warn users who 'liked' coronavirus hoaxes

Facebook will soon let you know if you shared or interacted with dangerous coronavirus misinformation on the site, the latest in a string of aggressive efforts the social media giant is taking to contain an outbreak of viral ...

Business

German plexiglass firm churns out virus shields

Touted as a simple but effective shield against coronavirus infections, transparent screens have sprung up at supermarket tills and pharmacies across Germany. For plexiglass manufacturer Claus Mueller, business has never ...

Business

Mideast airlines lose $7B as airports shut to combat virus

Seven Middle Eastern countries have suspended all commercial flights due to a fast-spreading new virus as the aviation industry's largest trade association announced Thursday that airlines in the region have already lost ...

Internet

Facebook bug wrongly deleted authentic coronavirus news

Facebook said a bug in its anti-spam system temporarily blocked the publication of links to news stories about the coronavirus. Guy Rosen, Facebook's vice president of integrity, said on Twitter Tuesday that the company was ...

page 1 from 4

Virus

I: dsDNA viruses II: ssDNA viruses III: dsRNA viruses IV: (+)ssRNA viruses V: (−)ssRNA viruses VI: ssRNA-RT viruses VII: dsDNA-RT viruses

A virus (from the Latin virus meaning toxin or poison) is a microscopic infectious agent that can reproduce only inside a host cell. Viruses infect all types of organisms: from animals and plants, to bacteria and archaea. Since the initial discovery of tobacco mosaic virus by Martinus Beijerinck in 1898, more than 5,000 types of virus have been described in detail, although most types of virus remain undiscovered. Viruses are ubiquitous, as they are found in almost every ecosystem on Earth, and are the most abundant type of biological entity on the planet. The study of viruses is known as virology, and is a branch of microbiology.

Viruses consist of two or three parts: all viruses have genes made from either DNA or RNA, long molecules that carry genetic information; all have a protein coat that protects these genes; and some have an envelope of fat that surrounds them when they are outside a cell. Viruses vary in shape from simple helical and icosahedral shapes, to more complex structures. They are about 1/100th the size of bacteria. The origins of viruses in the evolutionary history of life are unclear: some may have evolved from plasmids—pieces of DNA that can move between cells—while others may have evolved from bacteria. In evolution, viruses are an important means of horizontal gene transfer, which increases genetic diversity.

Viruses spread in many ways; plant viruses are often transmitted from plant to plant by insects that feed on sap, such as aphids, while animal viruses can be carried by blood-sucking insects. These disease-bearing organisms are known as vectors. Influenza viruses are spread by coughing and sneezing, and others such as norovirus, are transmitted by the faecal-oral route, when they contaminate hands, food, or water. Rotaviruses are often spread by direct contact with infected children. HIV is one of several viruses that are transmitted through sexual contact.

Not all viruses cause disease, as many viruses reproduce without causing any obvious harm to the infected organism. Viruses such as hepatitis B can cause life-long or chronic infections, and the viruses continue to replicate in the body despite the hosts' defence mechanisms. In some cases, these chronic infections might be beneficial as they might increase the immune system's response against infection by other pathogens. However, in most cases viral infections in animals cause an immune response that eliminates the infecting virus. These immune responses can also be produced by vaccines that give lifelong immunity to a viral infection. Microorganisms such as bacteria also have defences against viral infection, such as restriction modification systems. Antibiotics have no effect on viruses, but antiviral drugs have been developed to treat both life-threatening and more minor infections.

This text uses material from Wikipedia, licensed under CC BY-SA