Feline Immunodeficiency Virus

Feline Immunodeficiency Virus is commonly abbreviated to FIV

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

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

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

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