Portal:Viruses

Henipaviruses are a genus of RNA viruses in the Paramyxoviridae family. The variably shaped, 40–600 nm diameter, enveloped capsid contains a single-stranded, negative-sense RNA genome of 18.2 kb, with six genes. The cellular receptor is in the ephrin family. The natural hosts are predominantly bats, mainly the Pteropus genus of megabats (flying foxes) and some microbats. Bats infected with Hendra virus develop viraemia and shed virus in urine, faeces and saliva for around a week, but show no signs of disease. Henipaviruses can also infect humans and livestock, causing severe disease with high mortality, making the group a zoonootic disease. Transmission to humans sometimes occurs via an intermediate domestic animal host.

The first henipavirus, Hendra virus, was discovered in 1994 as the cause of an outbreak in horses in Brisbane, Australia. Nipah virus was identified a few years later in Malaysia as the cause of an outbreak in pigs. Three further species have since been recognised: Cedar and Kumasi viruses in bats, and Mòjiāng virus in rodents. Their emergence as human pathogens has been linked to increased contact between bats and humans. Human disease has been confined to Australia and Asia, but members of the genus have also been found in African bats. A veterinary vaccine against Hendra virus is available but no human vaccine has been licensed.

• ...that Hungarian veterinarian József Marek, the first to identify Marek's disease (symptom pictured; right), also developed a remedy for liver fluke in cattle and a nasogastric tube for treating horse colic?
• ...that because photomicrographs of Longan witches broom-associated virus were not published, the virus was not initially accepted as the cause of the eponymous disease?
• ...that Shetlander Johnnie Notions, a physician with no formal medical background, developed a smallpox inoculation that successfully immunised thousands of people before Jenner's vaccine was available?
• ...that the Kivu Ebola epidemic was declared a Public Health Emergency of International Concern on 17 July 2019?
• ...that Larry Kramer frequently invoked the AIDS–Holocaust metaphor and compared Reagan Administration officials to Nazi war criminals?

Rosalind Elsie Franklin (25 July 1920 – 16 April 1958) was a British biophysicist and X-ray crystallographer who made critical contributions to the understanding of the fine molecular structures of DNA, RNA and viruses.

Franklin led pioneering research on the structure of tobacco mosaic virus (TMV), a rod-like RNA virus, using X-ray crystallography. She first showed that, contrary to contemporary opinion, TMV virus particles were all of the same length. With Kenneth Holmes, she showed the virus's coat is composed of protein molecules arranged in helices. She designed and built a model of the virus to be exhibited at the 1958 World's Fair. She speculated that the virus is hollow, and correctly hypothesized that the RNA of TMV is single-stranded. Her work, together with that of Donald Caspar, revealed that the viral RNA is wound along the inner surface of the hollow virus. Her laboratory, which also included Aaron Klug, studied other plant viruses, including turnip yellow mosaic virus and viruses infecting potato, tomato and pea. Franklin also worked on icosahedral animal viruses, including poliovirus.

Franklin is commemorated in the Rosalind Franklin University of Medicine and Science.

February 1939: First virology journal, Archiv für die gesamte Virusforschung, appeared

8 February 1951: Establishment of the HeLa cell line from a cervical carcinoma biopsy, the first immortal human cell line

12 February 1892: Dmitri Ivanovsky (pictured) demonstrated transmission of tobacco mosaic disease by extracts filtered through Chamberland filters; sometimes considered the beginning of virology

19 February 1966: Prion disease kuru shown to be transmissible

23 February 2018: Baloxavir marboxil, the first anti-influenza agent to target the cap-dependent endonuclease activity of the viral polymerase, approved in Japan

27 February 2005: H1N1 influenza strain resistant to oseltamivir reported in a human patient

24 February 1977: Phi X 174 sequenced by Fred Sanger and coworkers, the first virus and the first DNA genome to be sequenced

28 February 1998: Publication of Andrew Wakefield's Lancet paper, subsequently discredited, linking the MMR vaccine with autism, which started the MMR vaccine controversy

Nevirapine (also Viramune) is an antiretroviral drug used in the treatment of HIV/AIDS caused by HIV-1. It was the first non-nucleoside reverse transcriptase inhibitor to be licensed, which occurred in 1996. Like nucleoside inhibitors, nevirapine inhibits HIV's reverse transcriptase enzyme, which copies the viral RNA into DNA and is essential for its replication. Unlike nucleoside inhibitors, it binds not in the enzyme's active site but in a nearby hydrophobic pocket, causing a conformational change in the enzyme that prevents it from functioning. Mutations in the pocket generate resistance to nevirapine, which develops rapidly unless viral replication is completely suppressed. The drug is therefore only used together with other anti-HIV drugs in combination therapy. The HIV-2 reverse transcriptase has a different pocket structure, rendering it inherently resistant to nevirapine and other first-generation NNRTIs. A single dose of nevirapine is a cost-effective way to reduce mother-to-child transmission of HIV, and has been recommended by the World Health Organization for use in resource-poor settings. Other protocols are recommended in the United States. Rash is the most common adverse event associated with the drug.

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