Diseases, Conditions, Syndromes

Common food additive may weaken defenses against influenza

Research conducted in mice suggests the food additive tert-butylhydroquinone (tBHQ)—found in many common products from frozen meat to crackers and fried foods—suppresses the immune response the body mounts when fighting ...

Immunology

Immunotherapy kicks and kills HIV by exploiting a common virus

In a first on the quest to cure HIV, University of Pittsburgh Graduate School of Public Health scientists report today in EBioMedicine that they've developed an all-in-one immunotherapy approach that not only kicks HIV out ...

Diseases, Conditions, Syndromes

Synthetic antibody rapidly protects mice and monkeys from Zika

A DNA-encoded monoclonal antibody prevents Zika infection in mice and non-human primates, researchers report April 5th in the journal Molecular Therapy. Injections of synthetic DNA encoding the potent anti-Zika monoclonal ...

Diseases, Conditions, Syndromes

Researchers make progress toward Epstein-Barr virus vaccine

A research team led by scientists from NIH's National Institute of Allergy and Infectious Diseases (NIAID) has determined how several antibodies induced by Epstein-Barr virus (EBV), a herpesvirus that causes infectious mononucleosis ...

Diseases, Conditions, Syndromes

Risk of congenital Zika syndrome greater than previously thought

Zika virus infection during pregnancy was first linked to birth defects during the outbreak in the Americas in 2015 and 2016; however, the Zika virus was discovered decades ago. Why then were adverse outcomes during pregnancy ...

Medical research

New approach to tackle Ebola and other deadly infections

Medical Research Council scientists have isolated therapeutic antibodies from healthy volunteers exposed to the Ebola vaccine but not Ebola virus itself, suggesting that protective therapies could be developed from people ...

Diseases, Conditions, Syndromes

Researchers create molecules with strong anti-Zika virus potential

The Zika virus is widely known for causing microcephaly and other brain defects in the fetuses of pregnant, infected women. Currently, there are no approved antiviral therapies specifically designed to treat Zika, but researchers ...

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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