FIV Case Example

Question 1

What type of virus is feline immune deficiency virus?

Answer 1

T lymphotrophic retrovirus

Question 2

What type of cat is most susceptible to FIV?

Answer 2

Sexually intact males:
- Increased risk for fighting behaviour
- Increased bite-wound transmission

Question 3

How does FIV work?

Answer 3

Pathogen enters host cells - lymphocytes
Viral genes / enzymes are released
Host cells internally replicate viral components
Further viral particulates are released

Question 4

Describe the acute phase of FIV infection

Answer 4

Mild illness shortly after exposure
Viraemia (red line) spikes as the virus replicates rapidly.
CD4+ T cells decline as FIV targets them using CD134 as the primary receptor.
The immune system responds by producing antibodies (blue dotted line), which helps reduce viraemia.

Question 5

Describe the sub-acute phase of FIV infection

Answer 5

The virus enters a latent state—cats often appear healthy, asymptomatic.
However, CD4+ T cells continue to decline slowly (dashed pink line).
FIV mutates its surface proteins to evade immune detection.
Viraemia remains low but persistent.

Question 6

Describe the senescence (secondary phase) caused by FIV infection

Answer 6

Eventually, the CD4+ count drops critically, weakening immune defences.
CD8+ T cells become more numerous than CD4+, but they can’t fully control the virus.
Cats are now prone to secondary infections (e.g., stomatitis, respiratory infections, or neoplasia).
Viraemia spikes again as immune control fails.

Question 7

What are the clinical signs of FIV?

Answer 7

There are no typical clinical signs
Cats present with persisting infections which they should be able to fight off
Maybe several concurrent infectious problems:
Weight loss, Pyrexia, Neurological disease, Oral infections, Enteritis, Respiratory infection

Question 8

Describe the diagnosis and treatment of FIV

Answer 8

Supportive care and treatment of secondary signs
PCR diagnostics
Vaccine exists but not UK licensed.