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New page: {{unfinished}} {{toplink |linkpage =Viruses |linktext =VIRUSES |sublink1=Retroviridae |subtext1=RETROVIRIDAE |pagetype =Bugs }} <br> ====Antigenicity==== *Main envelope protein: gp70, wi...
{{unfinished}}
{{toplink
|linkpage =Viruses
|linktext =VIRUSES
|sublink1=Retroviridae
|subtext1=RETROVIRIDAE
|pagetype =Bugs
}}
<br>
====Antigenicity====
*Main envelope protein: gp70, with 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
{{toplink
|linkpage =Viruses
|linktext =VIRUSES
|sublink1=Retroviridae
|subtext1=RETROVIRIDAE
|pagetype =Bugs
}}
<br>
====Antigenicity====
*Main envelope protein: gp70, with 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