Feline Retrovirus Infection (Rolph)

Question 1

What is the etiology of FeLV?

Answer 1

• Gamma retrovirus
• Protein core of single strended RNA
• Protected by viral envelope
  
  • gp70: main envelope protein that determines subgroup and host range in vitro

Question 2

What are the types of retroviruses and some examples?

Answer 2

• Endogenous
  
  • Inherited (non-pathogenic; passed through generations)
• Exogenous
  
  • Foreign (pathogenic)
  • Can be horizontally transmitted
  • FeLV/FIV/FeSFV

Question 3

What are the subgroups of FeLV?

Answer 3

• FeLV-A (only infectious subgroup)
• FeLV-B
• FeLV-C
• FeLV-T
• FeLV-myc

Question 4

How do FeLV infections spread and replicate?

Answer 4

• Oronasal route: replicates in salivary glands and respiratory epithelium (initial)
• May spread to the bone marrow
  
  • Infects hematopoietic precursor cells
  • Transcribed by RT into DNA provirus
  • DNA copies of viral RNA transcribed and integrated into daughter cells (infect them)

Question 5

Describe details about FeLV-B.

Answer 5

Recombinant between transmissible FeLV-A and endogenous B envelope genes

• 50% of FeLV+ cats are positive for subgroup B
• Associated with neoplasia

Question 6

Describe FeLV-C.

Answer 6

Mutant variant of subgroup A

• 1% cats positive for subgroup C
• Associated w/ non-regenerative anemias

Question 7

What’s unique about FeLV-T?

Answer 7

• Highly cytotoic to T lymphocytes
• Immunosuppression

Question 8

What’s the past and current prevalence of FeLV?

Answer 8

• Previously large problem in pedigree cats
  
  • Abyssinians: prevalence about. 35%
  • Approx. 21% in sick cats
• Prevalence significantly decreased currently
  
  • 1% in healthy cat population
  • Prevalence higher in sick and “at risk” cats

Question 9

How is FeLV transmitted?

Answer 9

• Saliva
• Milk
• Blood
• Urine
• Other body secretions
• Close, prolonged contact (mutual grooming, sharing food bowls and litter boxes)

Question 10

What’s the age resistance with FeLV?

Answer 10

• Young cats more susceptible (vaccinate until 3 yrs. old)
• Higher antibody titers in adults (hard to infect)
• Higher rate of persistent viremia in kittens (don’t clear virus)

Question 11

What mechanisms contribute to FeLV age resistance?

Answer 11

• FeLV receptor numbers
• Macrophage function