Lecture 9: Feline Viruses 2

Question 1

What is the agent causing FIP in cats? What type of virus is it?

Answer 1

Agent: Feline Infectious Peritonitis virus (mutated feline coronavirus)

• (+)ssRNA, enveloped

Question 2

What is the pathogenesis of FIP? And how does that impact virus detection?

Answer 2

• Feline enteric coronavirus replicate in GI epithelium and may mutate to FIPV (spike protein mutation)
  o Can be in body for month/years sub clinically
• FIPV target macrophages (= systemic infection)
  o No viral antigens expressed by infected macrophages = low immune response
• Short viremia (7d peak) = difficult to dx via seeing in blood (RT-PCR)

Question 3

How are the agent(s) impacting FIP transmitted

Answer 3

Transmit:
* FeCoV type 1: Shed 2-3d post infection in feces
1. Transient shedding for 2-3 mo
2. 10-15% carriers = persistent shedding
* FeCoV type 2: canine + feline coronavirus combination
1. Shed for 2 weeks, no carrier
* FIPV not transmissible between cats (must contract FeCoV and have it mutate)

Question 4

What are the 4 outcomes of feline coronavirus infection

Answer 4

• Resistance: 5-10%
• Transient infection: 70%
• Persistant infection /carrier: 10-15%
• FIP: 1-3% (rare outcome)

Question 5

What are the clinical signs of feline coronavirus infection

Answer 5

Clinically (FeCoV): sub clinical (rare = enteritis)

Question 6

What are the clinical signs of feline infectious peritonitis virus infection

Answer 6

Clinically (FIPV):
* Wet: abdominal distension/ascites with proteinaceous fluid (granulocytes) + ophthalmic signs (lesions/uveitis)
* Dry: ophthalmic signs (lesions/uveitis), numerous distributed pyogranulomas (lung/kidney/intestine)

Question 7

How to diagnose FIP

Answer 7

Dx: not easy:
* Use medical hx (young/multi-cat house/stress/pedigree)
* Clinical exam findings
* Diagnostic tests
o mRNA PCR – analyzing blood for viral replication in the blood (but high false + rate)
o RealPCR (via IDEXX) – identify the mutation, require biopsy granulomas

Question 8

How to treat FIP? Is it effective?

Answer 8

Tx: ramdicovir
Prognosis: 80% survival with tx (100% mortality w/o)

Question 9

What are the virus features of Lentivirus?

Answer 9

Feline Lentivirus
* RNA retrovirus

Question 10

How does feline lentivirus interact with host receptors? What cells do they replicate in?

Answer 10

o Receptor (CD134) on activated CD4 T cells
o Uses same co-receptors as HIV (CXCR4/CCR5)
o Can replicate in B cells/astrocytes/CD4/CD8

Question 11

What are risk factors common to FIV and FeLV

Answer 11

o Risk factors: stress/shelter/intact males/age/outdoor/previously sick

Question 12

How is FIV transmitted

Answer 12

• Transmit: sexual, blood-blood
  o low transmission between +female to offspring

Question 13

What are the clinical signs of FIV

Answer 13

• Clinically: acute mild febrile/slow progression + Feline AIDS
  o Chronic gingivostomatitis/rhinitis
  o Lymphadenopathy
  o Immune mediated glomerulonephritis – nephrotic syndrome (proteinuria/ascites/hypoproteinemia/dyspnea/peripheral edema)
  o Weight loss
  o Concurrent infection (virus/bacteria/fungi/parasite)
  o Similar lifespan of FIV vs non-FIV cat

Question 14

How is FIV controlled

Answer 14

• Tx: FIV vaccine discontinued

Question 15

What is a viral feature shared by FIV and FeLV

Answer 15

retroviruses

Question 16

What agent causes FeLV

Answer 16

gamma-retrovirus

Question 17

How is FeLV transmitted

Answer 17

• Transmit: saliva, nasal secretions, blood, feces, maternal milk

Question 18

What are 2 pathways of infection of FeLV

Answer 18

1. Transient viremia: >6mo old (older) = virus removal (fast Ig response before genome integration)
2. Latency and lifelong infection: <6mo old = long term viremia = future leukemia

Question 19

How to diagnose FeLV? How to differentiate between the type of infection?

Answer 19

• Dx: antigen SNAP test: uses antigen to differentiate between the transient state and latent/leukemia state

Question 20

How does FeLV subgroup impact clinical outcome

Answer 20

• Subgroups: 4 groups (A, B, C, T)
  o B/C/T are derivatives of type A
  o More pathogenicity when they recombine – ex. FeLV B = increased frequency of neoplasia/higher virus load

Question 21

How to protect/control against FeLV? What are the potential concerns?

Answer 21

• Control: vaccine: not 100% protective – only recommended for outdoor cats, associated with feline injection site sarcoma (associated with adjuvant - alum)
  o Should use non-adjuvanted/modified-live/recombinant vaccine (no modified live vaccine for FeLV)