Difference between revisions of "Feline Leukemia Virus"

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#REDIRECT[[Feline Leukaemia Virus]]
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{{unfinished}}
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{{toplink
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|linkpage =Viruses
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|linktext =VIRUSES
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|sublink1=Retroviridae
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|subtext1=RETROVIRIDAE
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|pagetype =Bugs
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}}
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<br>
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====Antigenicity====
 +
*Main envelope protein: gp70
 +
*3 antigenic subgroups:
 +
*Group A
 +
**is transmitted between cats
 +
**is monotypic: one vaccine covers all isolates
 +
**causes '''lymphosarcoma'''
 +
*Group B:
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**is recombinant with transmissible FeLV-A
 +
**increases the chance of '''thymic tumors'''
 +
*Group C:
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**is a mutant of A
 +
**isolates are rare, and occur as A+C mixtures
 +
**increases chances of '''anemia'''
 +
 
 +
====Pathogenesis====
 +
*FeLV is the "disease of friends": transmission usually occurs through '''mutual grooming'''
 +
*From the oropharynx, virus spreads to most tissues in the body to replicate, notably:
 +
**Bone marrow
 +
**Thymus
 +
**Salivary glands
 +
**Reproductive tract
 +
*Most kittens but only 30% of adults become '''viremic''' for life without producing antibody
 +
**20% of viremic cats die of tumors
 +
**30% of viremic cats die of FeLV-associated disease
 +
**80% die within three years of exposure
 +
*30% of adults exposed become '''latently infected''' and can become viremic when immunosuppressed
 +
*40% of exposed adults remain healthy and develop Ab and CD8+ Tcells after clearing the virus, without becoming reinfected or silent carriers
 +
 
 +
Clinical Signs:
 +
*'''Leukemia'''
 +
*'''Multicentric lymphosarcoma''': B or T cell tumors, which may be palpable as enlarged lymph nodes (particularly mesenteric)
 +
*'''Thymic lymphosarcoma''': T cell tumors, with only the thymus enlarged
 +
**Results in dyspnoea
 +
**Confirmed by radiography
 +
*'''Alimentary lymphosarcoma''': B cell tumors of the Peyer's patches
 +
 
 +
FeLV-associated disease:
 +
*'''Immunodepression''' causing secondary disease
 +
*'''Reproductive failure''': FeLV crosses the placenta, causing fetal resorption or viremic kittens with thymic aplasia
 +
 
 +
====Epidemiology====
 +
*Vertical transmission of FeLV-A from mother to kittens either via placenta, grooming, or milk
 +
*Horizontal transmission occurs via saliva during mutual grooming
 +
*Recovery linked to age and presence of maternal antibody
 +
*Particular concern for intensively bred cats because of crowding, etc.
 +
 
 +
====Diagnosis====
 +
*FeLV should be suspect in any cat with '''recurrent bacterial infections''', '''anemia''' or '''weight loss'''
 +
*'''ELISA''' for '''Antigen''' (capsid protein p27 or envelope protein gp70)
 +
*'''Immunochromatography''' is now trusted as ELISA testing can give false positives
 +
*'''Virus isolation''' from heparinised blood can now be performed to confirm a positive diagnosis
 +
 
 +
====Control====
 +
*Antigen positive sick cats should be destroyed
 +
*Healthy positive cats should have diagnosis confirmed
 +
*Vaccination:
 +
**Should take place once antigen-negative status has been determined
 +
**'''Leukogen''': 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

Revision as of 19:15, 18 October 2008


 This article is still under construction.


Infectious agents and parasitesWikiBugs Banner.png
VIRUSES
RETROVIRIDAE



Antigenicity

  • Main envelope protein: gp70
  • 3 antigenic subgroups:
  • Group A
    • is transmitted between cats
    • is monotypic: one vaccine covers all isolates
    • causes lymphosarcoma
  • Group B:
    • is recombinant with transmissible FeLV-A
    • increases the chance of thymic tumors
  • Group C:
    • is a mutant of A
    • isolates are rare, and occur as A+C mixtures
    • increases chances of anemia

Pathogenesis

  • FeLV is the "disease of friends": transmission usually occurs through mutual grooming
  • From the oropharynx, virus spreads to most tissues in the body to replicate, notably:
    • Bone marrow
    • Thymus
    • Salivary glands
    • Reproductive tract
  • Most kittens but only 30% of adults become viremic for life without producing antibody
    • 20% of viremic cats die of tumors
    • 30% of viremic cats die of FeLV-associated disease
    • 80% die within three years of exposure
  • 30% of adults exposed become latently infected and can become viremic when immunosuppressed
  • 40% of exposed adults remain healthy and develop Ab and CD8+ Tcells after clearing the virus, without becoming reinfected or silent carriers

Clinical Signs:

  • Leukemia
  • Multicentric lymphosarcoma: B or T cell tumors, which may be palpable as enlarged lymph nodes (particularly mesenteric)
  • Thymic lymphosarcoma: T cell tumors, with only the thymus enlarged
    • Results in dyspnoea
    • Confirmed by radiography
  • Alimentary lymphosarcoma: B cell tumors of the Peyer's patches

FeLV-associated disease:

  • Immunodepression causing secondary disease
  • Reproductive failure: FeLV crosses the placenta, causing fetal resorption or viremic kittens with thymic aplasia

Epidemiology

  • Vertical transmission of FeLV-A from mother to kittens either via placenta, grooming, or milk
  • Horizontal transmission occurs via saliva during mutual grooming
  • Recovery linked to age and presence of maternal antibody
  • Particular concern for intensively bred cats because of crowding, etc.

Diagnosis

  • FeLV should be suspect in any cat with recurrent bacterial infections, anemia or weight loss
  • ELISA for Antigen (capsid protein p27 or envelope protein gp70)
  • Immunochromatography is now trusted as ELISA testing can give false positives
  • Virus isolation from heparinised blood can now be performed to confirm a positive diagnosis

Control

  • Antigen positive sick cats should be destroyed
  • Healthy positive cats should have diagnosis confirmed
  • Vaccination:
    • Should take place once antigen-negative status has been determined
    • Leukogen: 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
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