Avian sarcoma leukosis virus
Avian leukosis virus | |
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Virus classification | |
(unranked): | Virus |
Realm: | Riboviria |
Kingdom: | Pararnavirae |
Phylum: | Artverviricota |
Class: | Revtraviricetes |
Order: | Ortervirales |
Family: | Retroviridae |
Genus: | Alpharetrovirus |
Species: | Avian leukosis virus
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Avian sarcoma leukosis virus (ASLV) is an
Avian sarcoma leukosis virus is characterized by a wide range of tumors, the most common of which are
Occurrence
History
By the 1960s, ASLV became a problem with egg-laying hens and effort was made to isolate the disease. However, the movement was unsuccessful in maintaining leukosis-free flocks. In 1961,
Lymphoid leukosis was eradicated in primary breeders in the 1980s and 1990s which dramatically reduced the incidence of the disease in commercial laying hens. Commercial broilers are still struggling with ALV-J virus in many countries. Layers, broilers, local chicken breeds, and even mallards may still become infected, and there are currently no available vaccines to combat the virus.[7]
Today, research is carried out on ASLV in order to better understand retroviral cell entry. Since ASLV uses distinct cellular receptors to gain entry into cells, it has proven useful for understanding the early events in retroviral infection.[8] A detailed understanding of retroviral cell entry may lead to the discovery of ways in which to block the viruses from entering cells. Retroviruses also have the potential to serve as gene delivery vectors in gene therapy.[citation needed]
Classification
ASLV is a Group VI virus of the family Retroviridae. It is of the genus Alpharetrovirus, and has a C-type morphology. Hence, it is an enveloped virus with a condensed, central core, and has barely visible envelope spikes, or proteins.[5]
ASLV is divided into six subgroups, labelled A through E and J, each having a different
Viral structure and composition
Like many retroviruses, ASLV consists of a lipid envelope containing transmembrane and cell surface
Viral glycoprotein-receptor interactions are required to initiate membrane fusion of the virus and cell. The surface glycoproteins contain the major domains that interact with the host cell receptor while the transmembrane (TM) glycoproteins anchor the surface glycoproteins to the virus membrane. The TM glycoproteins are directly involved in the fusion of the virus and host membranes for entry. The surface glycoproteins for subgroups A-E are almost identical and include the conservation of all cysteine amino acid residues. Viral specificity is determined by five hyper variable regions, vr1, vr2, hr1, hr2, and vr3, on the surface glycoproteins. Binding specificity is determined primarily by the hr1 and hr2 regions, with the vr3 region contributing to receptor recognition but not to binding specificity of the viral glycoprotein and cellular receptor.[11]
In chicken
ASLV is genetically closely related to the Rous sarcoma virus (RSV), but unlike RSV, ASLV does not contain the src gene, which codes for a tyrosine kinase, and does not transform the fibroblasts that it infects.[2] Both RSV and ASLV contain the gag gene, which is common to most retroviruses and encodes for the capsid proteins, and the pol gene which encodes for the reverse transcriptase enzyme. ASLV and some RSVs also contain the env gene, which encodes a precursor polyprotein that assembles in the endoplasmic reticulum. The polyproteins are then transported to the Golgi apparatus, glycosylated and cleaved to produce two glycoproteins: one surface and one transmembrane.[8]
Resources
The Avian Diagnostic and Oncology Laboratory, in East Lansing, MI is the primary laboratory for research in ALV and other tumor viruses.
The American Association of Avian Pathologists maintains a fact sheet on viral tumor diseases.
References
- ^ "Leukosis/Sarcoma Group". The Merck Veterinary Manual. 2006. Retrieved 23 June 2007.
- ^ PMID 17018135.
- ISBN 978-1-118-71973-2.
- ^ a b Riddell, C. (May–June 1999). "The current problem with Avian Leukosis J Virus". California Poultry Letter. University of California – Cooperative Extension. Archived from the original on 24 July 2011. Retrieved 12 May 2008.
- ^ ISBN 978-0-87969-571-2.
- ^ a b c All Nobel Laureates
- PMID 36217167.
- ^ PMID 11134286.
- PMID 15564460.
- PMID 16364732.
- PMID 2824857.
- PMID 2981357.
- PMID 15147387.