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 derivatives of diamond-like compound adamantane (model pictured) are used as drugs against flu and Parkinson's disease?
• ...that for 36 years, only two polyomaviruses were known to infect humans?
• ...that Ali Maow Maalin was the last person in the world to be infected with naturally occurring smallpox?
• ...that in his 2005 book Race Against Time, the UN Special Envoy for HIV/AIDS in Africa Stephen Lewis claimed the spread of AIDS across Africa is partly due to a succession of disastrous economic policies promoted by international financial institutions?
• ...that his son's infection with polio in 1930 led electrical engineer Reinhold Rudenberg to develop an electron microscope as a tool to study the poliovirus?

Edward Jenner (1749–1823) was an English physician and scientist who pioneered the smallpox vaccine, the world's first vaccine. Noting the common observation that milkmaids were generally immune to smallpox, Jenner postulated that the pus in the blisters that milkmaids received from cowpox (a similar but much less virulent disease) protected them from smallpox. In 1796, Jenner tested his hypothesis by inoculating an eight-year-old boy with pus from an infected milkmaid. He subsequently repeatedly challenged the boy with variolous material, then the standard method of immunisation, without inducing disease. He published a paper including 23 cases in 1798. Although several others had previously inoculated subjects with cowpox, Jenner was the first to show that the procedure induced immunity to smallpox. He later successfully popularised cowpox vaccination.

Jenner is often called "the father of immunology", and his work is said to have saved more lives than that of any other individual.

May 1955: First issue of Virology; first English-language journal dedicated to virology

4 May 1984: HTLV-III, later HIV, identified as the cause of AIDS by Robert Gallo and coworkers

5 May 1939: First electron micrographs of tobacco mosaic virus taken by Helmut Ruska and coworkers

5 May 1983: Structure of influenza neuraminidase solved by Jose Varghese, Graeme Laver and Peter Colman

8 May 1980: WHO announced formally the global eradication of smallpox

11 May 1978: SV40 sequenced by Walter Fiers and coworkers

12 May 1972: Gene for bacteriophage MS2 coat protein is sequenced by Walter Fiers and coworkers, the first gene to be completely sequenced

13 May 2011: Boceprevir approved for the treatment of chronic hepatitis C virus (HCV) infection, the first direct-acting antiviral for HCV

14 May 1796: Edward Jenner inoculated James Phipps (pictured) with cowpox

15/16 May 1969: Death of Robert Rayford, the earliest confirmed case of AIDS outside Africa

18 May 1998: First World AIDS Vaccine Day

20 May 1983: Isolation of the retrovirus LAV, later HIV, by Luc Montagnier, Françoise Barré-Sinoussi and coworkers

23 May 2011: Telaprevir approved for the treatment of chronic HCV infection

25 May 2011: WHO declared rinderpest eradicated

31 May 1937: First results in humans from the 17D vaccine for yellow fever published by Max Theiler and Hugh H. Smith

Two polio vaccines are used against the paralytic disease polio. The first, developed by Jonas Salk, consists of inactivated poliovirus. Based on three wild virulent strains, inactivated using formalin, it is administered by injection and is very safe. It confers IgG-mediated immunity, which prevents poliovirus from entering the bloodstream and protects the motor neurons, eliminating the risk of bulbar polio and post-polio syndrome. The second, developed by Albert Sabin, originally consisted of three live virus strains, attenuated by growth in cell culture. Since 2016, only two strains have generally been included. They contain multiple mutations, preventing them from replicating in the nervous system. The Sabin vaccine stimulates both antibodies and cell-mediated immunity, providing longer-lasting immunity than the Salk vaccine. It can be administered orally, making it more suitable for mass vaccination campaigns. In around three cases per million doses, the live vaccine reverts to a virulent form and causes paralysis. Vaccination has reduced the number of wild-type polio cases from around 350,000 in 1988 to just 33 in 2018, and eradicated the disease from most countries.