Feline Immunodeficiency Virus

Feline Immunodeficiency Virus is commonly abbreviated to FIV

Antigenicity

• Unrelated to HIV
• No vaccinal protection between USA Petulama prototype and UK (Hayling Island) isolate

Hosts

• Cats, including large cats on game reserves

Pathogenesis

• Receptor: CD134, found on monocyte-derived macrophages and activated T cells
  • Net effect: disruption of acquired immune response
• Infected cats develop antibody whether or not they are able to clear the virus

Two versions:

• Avirulent:
  • Transient infection with no CD4 decline
• Virulent:
  • Progressive CD4 decline with three stages (may present indistinct)
    1. High circulating virus for 1-10 weeks with resulting lymphoid depletion and CD8CD4 double positive Tcell destruction, thymic aplasia esp in kittens
    2. Remission: decrease in circulating virus as immune response increases, followed by immune exhaustion
       • Increase in CD8+ production and antibody response
       • Paracortical T cells and lymphoid follicles expand in primary and secondary lymph tissue and may be visible as white nodules
    3. Rapidly progressing infection with high virus present
       • Feline AIDS presents in a minority of cases
       • Nonregenerative anemia
       • Leucopenia
       • Neutropenia
       • Skin infections
       • Usually followed by secondary infection as a result of immunosuppression
       • Virus-ridden T cell destroy normal T cells, causing chronic immunosuppression

Epidemiology

• Transfer via saliva, though usually through a bite (FIV is the disease of enemies)
• Can transfer via milk or mutual grooming in multicat households
• Also transferred via mating
• Particular concern amongst stray males: 3.5% of healthy UK cats are seropositive, but in stray toms, up to 10% are positive
• Four-fold more common in diseased cats than in healthy cats

Diagnosis

• ELISA for serum antibody
  • False positives occur, particularly in the presence of maternal Ab
• Positives can be confirmed by lab work (Western blotting)

Control

• No UK vaccine
• Healthy positive cats should have diagnose confirmed by further testing
• Isolate and castrate
• Preventative neutering of males