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| Also known as '''''FeLV | | Also known as '''''FeLV |
| + | [[Image:FeLV Electron Micrograph.jpg|thumb|right|175px|FeLV Electron Micrograph [http://phil.cdc.gov/phil/home.asp Public Health Image Library] Image #5610]] |
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| ==Introduction== | | ==Introduction== |
| + | [[Image:Kinetics of FeLV 2.jpg|thumb|right|200px|Kinetics of FeLV - Copyright Dr Brian Catchpole BVetMed PhD MRCVS]] |
| + | FeLV is an oncogenic mammalian type C retrovirus which causes neoplasia ([[Lymphoma|lymphoma]]), myelosuppression ([[Regenerative and Non-Regenerative Anaemias|anaemia]]) and immunosuppression (of [[Lymphocytes#T cells|T cells]]). Three different strains are currently recognised: |
| + | *FeLV-A -natural strain |
| + | *FeLV-B which formed through FeLV-A recombining with endogenous retroviral sequences in the feline genome. |
| + | *FeLV-C which formed from the spontaneous mutation of FeLV-A |
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| + | The virus replicates in the oropharyngeal lymphoid tissue causing a viraemia (the virus circulates in the bloodstream) which then spreads to the systemic lymphoid tissue. |
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| ==Pathogenesis== | | ==Pathogenesis== |
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| *Salivary glands | | *Salivary glands |
| *Reproductive tract | | *Reproductive tract |
− | Most kittens but only 30% of adults become '''viremic''' for life without producing antibody. The condition progresses in various forms: | + | Most kittens but only 30% of adults become '''viraemic''' for life without producing antibody. The condition progresses in various forms: |
− | *20% of viremic cats die of tumors | + | *20% of viraemic cats die of tumors |
− | *30% of viremic cats die of FeLV-associated disease | + | *30% of viraemic cats die of FeLV-associated disease |
| *80% die within three years of exposure | | *80% die within three years of exposure |
− | 30% of adults exposed become '''latently infected''' and can become viremic when immunosuppressed. | + | 30% of adults exposed become '''latently infected''' and can become viraemic when immunosuppressed. |
| 40% of exposed adults remain healthy and develop Ab and CD8+ T cells after clearing the virus, without becoming reinfected or silent carriers. | | 40% of exposed adults remain healthy and develop Ab and CD8+ T cells after clearing the virus, without becoming reinfected or silent carriers. |
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| *'''Thymic lymphosarcoma''': T cell tumors, with only the thymus enlarged -this may result in dyspnoea and can be confirmed by radiography | | *'''Thymic lymphosarcoma''': T cell tumors, with only the thymus enlarged -this may result in dyspnoea and can be confirmed by radiography |
| *'''Alimentary lymphosarcoma''': B cell tumors of the Peyer's patches | | *'''Alimentary lymphosarcoma''': B cell tumors of the Peyer's patches |
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| + | *Cutaneous horns on foot pads |
| + | *Epidermal and follicular epithelial hyperplasia, epidermal giant cells, dyskeratosis, necrosis, ulceration |
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| FeLV-associated disease: | | FeLV-associated disease: |
| *'''Immunodepression''' causing secondary disease | | *'''Immunodepression''' causing secondary disease |
− | *'''Reproductive failure''': FeLV crosses the placenta, causing fetal resorption or viremic kittens with thymic aplasia | + | *'''Reproductive failure''': FeLV crosses the placenta, causing fetal resorption or viraemic kittens with thymic aplasia |
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| ==Epidemiology== | | ==Epidemiology== |
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| ==Antigenicity== | | ==Antigenicity== |
− | *Main envelope protein: gp70
| + | Viral subgroups have been categorised based on the different abnormalities detected in the host cellular envelope protein gp70. This protein interacts with a cellular receptor, and can prevent already infected cells from being targeted by further viral organisms. |
− | *3 antigenic subgroups:
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− | *Group A
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− | **is transmitted between cats
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− | **is monotypic: one vaccine covers all isolates
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− | **causes '''lymphosarcoma'''
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− | *Group B:
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− | **is recombinant with transmissible FeLV-A
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− | **increases the chance of '''thymic tumors'''
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− | *Group C:
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− | **is a mutant of A
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− | **isolates are rare, and occur as A+C mixtures
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− | **increases chances of '''anemia'''
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| + | There are 3 antigenic subgroups which are defined by the gp70 regulated viral response: |
| + | *Group A is transmitted between cats and is monotypic: one vaccine covers all isolates. Infection with this viral subgroup leads to '''[[Lymphoma|lymphosarcoma]]'''. |
| + | *Group B is recombinant with transmissible FeLV-A; infection with viruses of this subgroup increases the chance of developing '''[[Thymus Neoplasia|thymic tumours]]'''. |
| + | *Group C is a mutant of subgroup A. Isolates are rare, and occur as A+C mixes, leading to an increased chance of developing '''[[Regenerative and Non-Regenerative Anaemias|anaemia]]'''. |
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| ==Diagnosis== | | ==Diagnosis== |
− | *FeLV should be suspect in any cat with '''recurrent bacterial infections''', '''anemia''' or '''weight loss''' | + | *FeLV should be suspect in any cat with '''recurrent bacterial infections''', '''anemia''' or '''weight loss'''. Diagnostic tests available for confirmation of disease status include: |
− | *'''ELISA''' for '''Antigen''' (capsid protein p27 or envelope protein gp70) | + | *'''[[ELISA testing|ELISA]]''' for FeLV antigens (capsid protein p27 or envelope protein gp70) |
− | *'''Immunochromatography''' is now trusted as ELISA testing can give false positives | + | *'''Immunochromatography''' is now preferred as ELISA testing can give false positives |
− | *'''Virus isolation''' from heparinised blood can now be performed to confirm a positive diagnosis | + | *'''Virus isolation''' from heparinised blood can be performed to confirm a positive diagnosis |
− | ELISA
| + | *[[Immunofluorescence]] |
− | **Rapid-Immuno-Migration | + | *PCR |
− | **Western Blot | + | *Rapid-Immuno-Migration |
− | **Virus Isolation
| + | *[[Western blot|Western Blot]] |
− | **Immunofluorescence
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− | **PCR
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| ==Infection Control== | | ==Infection Control== |
− | *Antigen positive sick cats should be destroyed
| + | Antigen positive cats with significant symptoms require euthanasia. Healthy positive cats should have the diagnosis confirmed by a second alternate testing method. |
− | *Healthy positive cats should have diagnosis confirmed
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− | *Vaccination:
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− | **Should take place once antigen-negative status has been determined
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− | **'''Leukogen''': Subunit vaccine (using envelope protein gp70) produced in ''E. coli'' mixed with Quill-A and alhydrogel
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− | **Others include inactivated virus and canarypox recombinants, but all MUST include FeLV-A
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− | (FeLV)
| + | ===Vaccination=== |
− | [[Image:FeLV Electron Micrograph.jpg|thumb|right|150px|FeLV Electron Micrograph [http://phil.cdc.gov/phil/home.asp Public Health Image Library] Image #5610]]
| + | Ideally, this should take place once antigen-negative status has been determined by laboratory testing. 'Leukogen' is a subunit vaccine (using envelope protein gp70) produced in ''E. coli'' mixed with Quill-A and alhydrogel. Others include inactivated virus and canarypox recombinants, but all MUST include FeLV-A. |
− | [[Image:Kinetics of FeLV 2.jpg|thumb|right|150px|Kinetics of FeLV - Copyright Dr Brian Catchpole BVetMed PhD MRCVS]]
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− | *Oncogenic retrovirus
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− | *Causes neoplasia (lymphoma), myelosuppression (anaemia) and immunosuppression (of [[Lymphocytes#T cells|T cells]])
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− | *2 strains:
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− | **FeLV-A
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− | ***Natural strain
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− | **FeLV-B
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− | ***Formed through FeLV-A recombining with endogenous retroviral sequences in the feline genome
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− | ***Increases the risks of lymphoma
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− | **FeLV-C
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− | ***Formed from the spontaneous mutation of FeLV-A
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− | ***Is more myelosuppressive
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− | *Virus replicates in the oropharyngeal lymphoid tissue causing a viraemia (virus circulating in the bloodstream) which then spreads to the systemic lymphoid tissue
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− | *Shed in saliva
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− | *Passed by oronasal route, e.g. mutual grooming
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− | *Kittens between 6 weeks and 6 months are most susceptible
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− | *60% of cats will become immune to the disease and recover
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− | *Cats that are persistently viraemic will progress to develop FeLV-associated diseases
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− | *Some cats will become viraemic again if treated with corticosteroids or stressed if the infection lies dormant in the [[Bone Marrow - Anatomy & Physiology|bone marrow]]
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| ==Treatment== | | ==Treatment== |
− | **Antibiotics for secondary infection
| + | Where treatment is undertaken, anti-retroviral therapy is indicated with antibiotics to control secondary infections. Prevention is a key element in the control and treatment of FeLV overall. |
− | **Anti-retroviral therapy
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− | *For vaccinations see [[Vaccines#Cat Vaccinations|here]]
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| + | {{Learning |
| + | |Vetstream = [https://www.vetstream.com/felis/Content/Disease/dis60141 Feline leukemia virus disease] |
| + | }} |
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− | [[Category:Mammalian Type C retrovirus ]][[Category:Cat]][[Category:Secondary Immunodeficiency]] | + | [[Category:Mammalian Type C retrovirus ]][[Category:Cat Viruses]][[Category:Lymphoreticular and Haematopoietic Diseases - Cat]][[Category:Alimentary Diseases - Cat]][[Category:Secondary Immunodeficiency]] |
− | [[Category:To_Do_-_Clinical/Viruses]] | + | [[Category:Lymphoreticular and Haemopoietic Diseases]] |
− | [[Category:To Do - Blood]][[Category:To Do - Clinical]][[Category:Lymphoreticular and Haemopoietic Diseases]] | + | [[Category:Anaemia|6]] |
| + | [[Category:Integumentary System - Viral Infections]] |