Changes

==Introduction==

==Introduction==

[[Image:Kinetics of FeLV 2.jpg|thumb|right|200px|Kinetics of FeLV - Copyright Dr Brian Catchpole BVetMed PhD MRCVS]]

[[Image:Kinetics of FeLV 2.jpg|thumb|right|200px|Kinetics of FeLV - Copyright Dr Brian Catchpole BVetMed PhD MRCVS]]

FeLV is an ncogenic 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 is an oncogenic 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-A -natural strain

*FeLV-B which formed through FeLV-A recombining with endogenous retroviral sequences in the feline genome.

*FeLV-B which formed through FeLV-A recombining with endogenous retroviral sequences in the feline genome.

*Reproductive tract

*Reproductive tract

Most kittens but only 30% of adults become '''viraemic''' 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.

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

==Epidemiology==

==Epidemiology==

*Group A is transmitted between cats and is monotypic: one vaccine covers all isolates. Infection with this viral subgroup leads to '''[[Lymphoma|lymphosarcoma]]'''.

*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 - Pathology|thymic tumours]]'''.

*Group B is recombinant with transmissible FeLV-A; infection with viruses of this subgroup increases the chance of developing '''[[Thymus - Pathology|thymic tumours]]'''.

*Group C is a mutant of subgroup A. Isolates are rare, and occur as A+C mixtures, leading to an increased chance of developing '''[[Regenerative and Non-Regenerative Anaemias|anaemia]]'''.

*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]]'''.

==Diagnosis==

==Diagnosis==

*FeLV should be suspect in any cat with '''recurrent bacterial infections''', '''anemia''' or '''weight loss'''. Diagnostic tests available for cinfirmation of disease sttus includes:

*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 testing|ELISA]]''' for FeLV antigens (capsid protein p27 or envelope protein gp70)

*'''[[ELISA testing|ELISA]]''' for FeLV antigens (capsid protein p27 or envelope protein gp70)

*'''Immunochromatography''' is now preferred as ELISA testing can give false positives

*'''Immunochromatography''' is now preferred as ELISA testing can give false positives