Reticuloendotheliosis Virus
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The reticuloendotheliosis virus ( scientifically Reticuloendotheliosis virus , REV ) is a retrovirus of the genus gamma retroviruses . It causes various neoplastic and non-neoplastic diseases in chickens and other domesticated birds such as turkeys and geese .
virus
The first prototypical REV isolate was isolated from a turkey in 1957. Little is known about the spread and mode of infection of REV. Many pet bird species have antibodies to REV without showing signs of disease. Manifest diseases caused by REV appear to be relatively rare and occur sporadically. The virus genome consists of an approximately 8.3 kb long single-stranded RNA with (+) polarity, which has the gene regions gag , pol and env typical for the retroviruses and no other accessory protein-coding regions.
Hypotheses of a non-avian origin of REV
Taxonomic studies showed a very close relationship to an endogenous retrovirus from the short-billed urchin ( Tachyglossus aculeatus ). In addition, all previous REV isolates are very similar in the nucleotide sequence, so that there cannot have been a longer evolution. This has led to the suspicion that REV is not a genuinely avian virus but may have entered domesticated avian species through veterinary manipulation. This hypothesis is supported by the observation that REV sequences have been found in two large DNA viruses that infect both birds: the fowlpox virus ( FWPV) and the chicken herpes virus 2 (GHV-2), the The causative agent of Marek's disease . Since both diseases are vaccinated and it is known that the respective vaccines were partially contaminated with REV, there is reason to assume that REV may have been spread in this way.
In 2013 Niewiadomska and Gifford published the hypothesis that the precursor to all reticuloendotheliosis viruses entered avian species through experiments with a bird malaria parasite in the 1930s to 1940s. At that time, Lowell T. Coggeshall sought in New York to an animal model for human malaria and identified in June 1937 a crested fireback ( Lophura ignita ) from the island of Borneo from the New York Zoological Park (now Bronx Zoo ) a Plasmodium species ( P. lophurae ), which could infect chicken chicks. The parasite was "passaged" (cultivated) in birds in the laboratory for several years. However, it later became clear that a second infectious agent was still being transmitted in addition to the parasite. This agent was characterized as Spleen necrosis virus in 1959 , a virus that was later classified as a member of the REV family. Since the parasite P. lophurae could never be found again in bird species in Borneo and the last remains of the original isolate were used up in the early 1980s, it is unclear which viruses P. lophurae contained exactly or from which organism they originated Viruses originated. It is also possible that these viruses were only introduced later during the transfer experiments. Extensive experiments with avian malaria and P. lophurae were carried out in the 1930s and 1940s against the backdrop of the Second World War . At the same time, experiments with attenuated birdpox and GHV-2 viruses were also carried out as vaccines. Niewiadomska and Gifford hypothesized that this is how REV got into GHV-2 and avipoxvirus vaccines and spread to bird populations around the world.
A similar case is the gibbon monkey leukemia virus (GaLV), which is also assumed to be an originally endogenous retrovirus in koala bears ( koala retrovirus , KoRV) that is transmitted to monkeys under conditions in zoo keeping has been.
Clinical pictures
Non-defective REVs cause a spectrum of symptoms in domestic chickens and ducks, which is summarized in English under the term runting disease syndrome ("stunting syndrome"). Affected animals suffer from failure to thrive, anemia, and developmental delay. In addition, chronic lymphoproliferative diseases ( malignant lymphomas ) can develop. The genetically defective so-called T-REV strain contains the retroviral oncogene v- rel in the genome and leads to a disease known as 'reticuloendotheliosis' from which the virus got its name. It is an acute malignant event in which various cell types are likely to be infected (lymphocytes, mesenchymal cells, etc.). T-REV and reticuloendotheliosis only exist under experimental laboratory conditions; they do not exist in the wild.
Individual evidence
- ↑ a b c d ICTV: ICTV Taxonomy history: Commelina yellow mottle virus , EC 51, Berlin, Germany, July 2019; Email ratification March 2020 (MSL # 35)
- ^ FR Robinson, MJ Twiehaus: Isolation of the avian reticuloendothelial virus (strain T). In: Avian Dis. 18, 1974, pp. 278-288.
- ↑ M. Barbacid , E. Hunter, SA Aaronson: Avian reticuloendotheliosis viruses: evolutionary linkage with mammalian type C retroviruses. In: J Virol. 30, 1979, pp. 508-514. PMID 89204 .
- ^ A b A. M. Niewiadomska, RJ Gifford: The Extraordinary Evolutionary History of the Reticuloendotheliosis Viruses. In: PLoS Biol. 11 (8), 2013, p. E1001642. doi: 10.1371 / journal.pbio.1001642
- ^ W. Trager: A new virus of ducks interfering with development of malaria parasite (Plasmodium lophurae). In: Proc Soc Exp Biol Med. 101, 1959, pp. 578-582.
- ↑ VN Kewalramani, AT Panganiban, M. Emerman: Spleen necrosis virus, an avian immunosuppressive retrovirus, shares a receptor with the type D simian retroviruses. In: J Virol. 66 (5), 1992, pp. 3026-3031. PMID 1313915 . (pdf)
- ↑ U. Fiebig, MG Hartmann, N. Bannert, R. Kurth, J. Denner: Transspecies Transmission of the Endogenous Koala Retrovirus. In: J Virol. 80 (11), 2006, pp. 5651-5654. doi: 10.1128 / JVI.02597-05
- ↑ LN Payne, K. Venugopal: Neoplastic diseases: Marek's disease, avian leukosis and reticuloendotheliosis. In: Rev Sci Tech. 19 (2), Aug 2000, pp. 544-564. PMID 10935279 . (pdf)