Related topics: hiv · influenza · immune system · cells · flu

Filter membrane renders viruses harmless

Viruses can spread not only via droplets or aerosols like the new coronavirus, but in water, too. In fact, some potentially dangerous pathogens of gastrointestinal diseases are water-borne viruses.

Research exposes new vulnerability for SARS-CoV-2

Northwestern University researchers have uncovered a new vulnerability in the novel coronavirus' infamous spike protein—illuminating a relatively simple, potential treatment pathway.

Possible new antivirals against COVID-19, herpes

In addition to antibodies and white blood cells, the immune system deploys peptides to fight viruses and other pathogens. Synthetic peptides could reinforce this defense but don't last long in the body, so researchers are ...

Dormant viruses activate during spaceflight

Herpes viruses reactivate in more than half of crew aboard Space Shuttle and International Space Station missions, according to NASA research published in Frontiers in Microbiology. While only a small proportion develop symptoms, ...

15,000-year-old viruses discovered in Tibetan glacier ice

Scientists who study glacier ice have found viruses nearly 15,000 years old in two ice samples taken from the Tibetan Plateau in China. Most of those viruses, which survived because they had remained frozen, are unlike any ...

Science races against tick-borne virus

Two groundbreaking discoveries by USC researchers could lead to medications and a vaccine to treat or prevent a hemorrhagic fever transmitted by a new tick species before it spreads across the United States.

New study shines light on mysterious giant viruses

In recent years, giant viruses have been unearthed in several of the world's most mysterious locations, from the thawing permafrost of Siberia to locations unknown beneath the Antarctic ice. But don't worry, "The Thing" is ...

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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