|Reston virus (RESTV)|
|Group:||Group V ((-)ssRNA)|
Reston virus (abbreviated RESTV) was first described in 1990 as a new "strain" of Ebola virus (EBOV), a result of mutation from Ebola virus. It is the single member of the species Reston ebolavirus, which is included into the genus Ebolavirus, family Filoviridae, order Mononegavirales. Reston virus is named after Reston, Virginia, US, where the virus was first discovered.
RESTV was discovered in crab-eating macaques from Hazleton Laboratories (now Covance) in 1989. This attracted significant media attention due to the proximity of Reston to the Washington, DC metro area, and the lethality of a closely related Ebola virus. Despite its status as a level-4 organism, Reston virus is non-pathogenic to humans, though hazardous to monkeys; the perception of its lethality was confounded due to the monkey's coinfection with Simian hemorrhagic fever virus (SHFV).
Pronunciation and nomenclature
Reston virus is pronounced ‘rɛstən vɑɪrəs (IPA) or res-tuhn vahy-ruhs in English phonetic notation. According to the rules for taxon naming established by the International Committee on Taxonomy of Viruses (ICTV), the name Reston virus is always to be capitalized, but is never italicized, and may be abbreviated (with RESTV being the official abbreviation).
Reston virus was first introduced as a new "strain" of Ebola virus in 1990. In 2000, it received the designation Reston Ebola virus and in 2002 the name was changed to Reston ebolavirus. Previous abbreviations for the virus were EBOV-R (for Ebola virus Reston) and most recently REBOV (for Reston Ebola virus or Reston ebolavirus). The virus received its current designation in 2010, when it was renamed Reston virus (RESTV).
A virus of the species Reston ebolavirus is a Reston virus (RESTV) if it has the properties of Reston ebolaviruses and if its genome diverges from that of the prototype Reston virus, Reston virus variant Pennsylvania (RESTV/Pen), by ≤10% at the nucleotide level.
While investigating on an outbreak of Simian hemorrhagic fever (SHFV) in November 1989, an electron microscopist from USAMRIID discovered filoviruses similar in appearance to Ebola virus in tissue samples taken from Crab-eating Macaque imported from the Philippines to Hazleton Laboratories in Reston, Virginia. The filovirus was further isolated by Dr. Peter B. Jahrling, and over the period of three months over a third of the monkeys died—at a rate of two or three a day.
Blood samples were taken from 178 animal handlers during the incident. Of them, six eventually seroconverted, testing positive using ELISA. They remained, however, asymptomatic. In January 1990, an animal handler at Hazelton cut himself while performing a necropsy on the liver of an infected Cynomolgus. Under the direction of the Center for Disease Control and Prevention (CDC) the animal handler was placed under surveillance for the duration of the incubation period. When the animal handler failed to become ill, it was concluded that the virus had a low pathogenicity in humans.
Following the discovery of a filovirus in Crab-eating Macaques, an investigation tracing the infection was conducted by the CDC. The monkeys were imported from the Philippines, which had no previous record of SHFV or ebolavirus infections. It was suspected that the monkeys contracted both diseases while in transit aboard KLM airlines before reaching Reston. Shipments were tracked to New York City, Texas, and Mexico City, none of which produced cases of infection.
By January 1990, Hazelton Laboratories recovered from its previous losses and began importing monkeys again from the same establishment in Manila that had provided the original animals. The imported monkeys became infected and were euthanized. In early February the CDC received reports of the disease in Alice, Texas. In March the Division of Quarantine at the CDC secured a temporary ban on the importation of monkeys into the United States from anywhere in the world.
Following the announcement of the filovirus disease outbreak in Reston, Virginia, a serosurvey was conducted to assess the prevalence of the infection. Of the several hundred serums received by the CDC, approximately ten percent showed some reaction to ebolavirus antigen—though usually at low levels. Counterintuitively, the majority of the monkeys found positive were from Indonesia.
In May 1990 an investigation led by Susan Fisher-Hoch, Steve Ostroff, and Jerry Jennings was sent to Indonesia. During the investigation, it was hypothesized that there could be a cross infection since monkeys suspected of illness were typically placed in gang cages containing up to twenty to thirty other monkeys suspected of illness. Upon arrival they were told that most of the monkeys were imported from the island of Sumatra. The investigation team found no trace of the virus in either case.
Following the investigation in Indonesia, an experiment was conducted in the level-4 lab at the CDC campus in DeKalb County, Georgia with thirty-two monkeys: sixteen Green monkeys (Cercopithecus aethiops) and sixteen Crab-eating Macaques. Half of the sixteen Green monkeys and Crab-eating Macaques were infected with Reston virus and the other half with Ebola virus. Ebola virus infection was lethal to nearly all monkeys. However, most of the monkeys infected with Reston virus recovered in a month. The surviving monkeys were kept for two years to detect any trace of the virus - none was found. However, the monkeys continued to possess a high level of antigen.
Following the test at the CDC campus in DeKalb County, two of the monkeys who had survived Reston virus infection were infected with a very large dose of the Ebola virus in an effort to produce an Ebola vaccine. One of the two monkeys remained resistant; the second died.
The physical building in which the outbreak occurred was demolished on 30 May 1995 and a new building constructed in its place. This facility, which is part of the Isaac Newton Square office park, at 1946 Isaac Newton Sq W, became a KinderCare, then became a Mulberry Child Care and preschool center as of 2007, and as of 2009 was once again a KinderCare.
Reston virus reemerged in Italy in 1992, and again in a monkey export facility in the Philippines in 1996.
On 11 December 2008, pigs from farms slightly north of Manila, Philippines tested positive for the virus. The CDC and the World Health Organization are investigating. On 23 January 2009, Philippine health officials announced that a hog farm worker had been infected with the virus. Although the man was asymptomatic and the source of the infection is uncertain, this could represent the first case of pig-to-human transmission of Reston virus - a fact that could cause concern, as pigs may be able to transmit more deadly diseases to humans. The situation is undergoing further investigation.
- ^ Hazleton Research Products 1946 Isaac Newton Square W, Reston, Virginia, United States
- ^ At the onset of infection the body does not produce detectable amounts of antibody within the Blood plasma, however this does not signify that the patient is free of infection. When the body begins to produce antibody, it becomes "seroconverted".
- ^ Ebola virus has not been confirmed to spread naturally by airborne means with the exception of experiments conducted by USAMRIID and the Soviet Union. Since Reston virus is closely related to Ebola virus, it was inferred that it could not spread by airborne means.
- ^ The test was developed for the 1976 Ebola virus epidemic. It responded well in outbreak situations where individuals had or have had a recent infection, however, the test conducted following Reston produced potentially ambiguous results.
- ^ In an effort to evaluate the original test, Dr. Karl Johnson from the CDC tested San Blas Indians from Central America: which have no history of Ebola virus infection. It produced a two percent positive. Other researchers later tested sera from Native Americans in Alaska and found a similar percentage of positive. To combat the false positives a more complex test based on the ELISA system was developed by Tom Kzaisek at USAMRIID which was later improved with Immunofluorescent antibody analysis (IFA). It was however not used during the serosurvey following Reston.
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