Virus de la leucémie féline
357282
31193138
2008-07-01T11:40:56Z
JLM
253964
Annulation des modifications 31193114 par [[Special:Contributions/82.255.66.173|82.255.66.173]] ([[User talk:82.255.66.173|Discuter]])gaminerie
{{ébauche|virus}}
{{Taxobox virus | Virus de la leucose féline | Defaut.svg | Légende}}
{{Taxobox groupe | {{virus Groupe VI}} }}
{{Taxobox famille | Retroviridae}}
{{Taxobox genre | Gammaretrovirus}}
{{Taxobox espèce virus | '''Virus de la leucose féline''' }}
{{Taxobox fin}}
Le '''virus de la leucose féline''' ('''FeLV''', ''Feline leukemia virus'') est un [[rétrovirus]], un virus dans lequel l'information génétique est contenue dans l'[[Acide ribonucléique|ARN]] au lieu de l'[[Acide désoxyribonucléique|ADN]]. Tous les rétrovirus, y compris le [[virus de l'immunodéficience féline]] (FIV) et le [[virus de l'immunodéficience humaine]] (VIH ou HIV), produisent une enzyme appelée [[transcriptase inverse]]. La transcriptase inverse leur permet d'insérer des copies de leur matériel génétique dans celui des cellules qu'ils ont infectées. Bien qu'on les prenne souvent par erreur comme un seul virus, le FeLV et le FIV diffèrent sous bien des aspects :
* Ils diffèrent entre autres par leur aspect : le FeLV est plutôt circulaire alors que le FIV est allongé.
* Les deux virus sont également assez différents sur le plan génétique, et leurs protéines de surface diffèrent en taille et en composition.
* Bien que de nombreuses maladies causées par le FeLV et le FIV soient similaires, les voies spécifiques par lesquelles elles sont causées sont différentes.
==Pouvoir pathogène==
*
<!--[[Cat]]s infected with FeLV serve as sources of infection. The virus is released from the body in saliva and nasal secretions. It is also transmitted, though not as often, in urine, feces, and milk from infected cats. Cat-to-cat transfer of the virus may occur from a bite wound, during mutual grooming, and sometimes even through the shared use of litter boxes and feeding dishes. Transmission can also take place from an infected mother cat to her kittens, either before they are born or while they are nursing. FeLV doesn't survive long outside a cat's body, probably less than a few hours under normal household conditions.
There are many possible outcomes as to how successfully the cat’s [[immune system]] will react to the virus. About forty percent of cats extinguish the virus. Sixteen percent of these fight it off due to minimal exposure to it. The other twenty-four percent resist the virus at phase four, which will be described later. All of this usually occurs between sixteen to eighteen weeks after the FeLV infection begins. About twenty percent are able to put the virus into a latent stage, in which the virus will remain until the cat becomes stressed causing the FeLV to re-emerge. About five to ten percent of cats go through a sequestered stage in which [[viremia]] is limited, intermittened, or absent altogether. Approximately thirty percent of cats go through the disease from start to finish, normally resulting in death.
Once the virus has entered the cat, there are six phases to a FeLV infection. Phase one is when the virus enters the cat, usually through the pharynx where it infects the epithelial cells and infects the tonsillar B-lymphocytes and macrophages. These white blood cells then filter down to the lymph nodes and begin to replicate. In phase two, the virus enters the blood stream and begins to distribute throughout the body. Phase three starts when the lymphoid system (produces antibodies to attack infected and cancerous cells) becomes infected with further distribution throughout the body. Phase four is the main point in the infection, where the virus can take over the body's immune system cause viremia. During this phase the hemolymphatic system and intestines become infected. If the cat's immune system does not fight off the virus, then it goes onto phase five where the [[bone marrow]] becomes infected. At this point, the virus will stay with the cat for the rest of its life. In this phase, the virus replicates and is released four to seven days later in infected neutrophils ([[white blood cell]]s), and sometimes lymphocytes, monocytes (white blood cell formed in the bone marrow), and eosinophils (another white blood cell). At this stage the cat's body is overwhelmed by infection and mucosal and glandular epithelial cells (tissue that forms a thin protective layer on exposed bodily surfaces and forms the lining of internal cavities, ducts, and organs) become infected. The virus replicates in epithelial tissues including salivary glands, oropharynx, stomach, esophagus, intestines, trachae, nasopharynx, renal tubules, bladder, pancreas, alveolar ducts, and sebaceous ducts from the muzzle.
The replication process of the FeLV virus is fairly straight forward. First the virus attaches to receptors on surface of the target cell. Then the virus penetrates the cell membrane, sheds its [[envelope (virus)|envelope]] and [[capsid]], and releases its single stranded RNA and reverse transcriptase. Reverse transcriptase, with the help of the cat's cellular enzymes, makes the ssRNA into double stranded DNA. The dsDNA circulates and integrates into the nucleus and attempts to incorporate into the cat's chromosomes. If the viral DNA is successful in incorporating into the cat's DNA it transcribes to mRNA. The new viral RNA, proteins, and reverse transcriptase are synthesized, assembled, and then bud from the plasma membrane as a new FeLV virus to infect another cell. When the dsDNA is integrated into the nucleus it can have four possible effects: productive infection, latent infection, insertional [[mutagenesis]] (in which the viral DNA is incorporated into a critical part of the DNA and mutates the cell), and finally failure of integration (where viral DNA accumulates in the cell and is toxic to it).-->
{{portail microbiologie}}
[[Catégorie:Santé du chat]]
[[Catégorie:Rétrovirus]]
[[de:Felines Leukosevirus]]
[[en:Feline leukemia virus]]
[[fi:Kissan leukoosi]]
[[sk:Komplex vírusovej leukémie mačiek]]