Diseases, Conditions, Syndromes

Poliovirus in London sewage: What you need to know

Just as we thought that monkeypox would be the new virus scare for 2022, the U.K. Health Security Agency (UKHSA) declared a national incident of repeated poliovirus detection in sewage in north and east London. Repeated positive ...

Vaccination

Challenge study shows efficacy of RSV vaccine in healthy adults

For healthy adults, the bivalent prefusion F respiratory syncytial virus (RSVpreF) vaccine is effective against symptomatic RSV infection and viral shedding, according to a study published in the June 23 issue of the New ...

Diseases, Conditions, Syndromes

Key facts you need to know about monkeypox

Media reports about an outbreak of monkeypox may sound scary, but there's no need for most people to take special steps to avoid getting the viral illness, an infectious disease expert says.

Medical research

Study finds repurposed drug inhibits enzyme related to COVID-19

With the end of the pandemic seemingly nowhere in sight, scientists are still very focused on finding new or alternative drugs to treat and stop the spread of COVID-19. In a first-of-its-kind study, researchers at the University ...

Diseases, Conditions, Syndromes

Polio virus detected in London sewage samples: WHO, UK

A type of poliovirus derived from vaccines has been detected in London sewage samples, the World Health Organization and British health officials said Wednesday, adding that more analysis was underway.

Diseases, Conditions, Syndromes

Why monkeypox may soon get a new name

Monkeypox may soon have a new name after scientists called for a change to dispel stereotypes of Africa being seen as a crucible of disease.

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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