Feline Retroviruses

Question 1

What is the viral core protein produced by infected cells that are detected by FeLV antigen tests?

Answer 1

p27

Question 2

Which cats are most susceptible to FeLV?

Answer 2

Young kittens

• Others include those in a high population density & outdoor cats

Question 3

How is FeLV transmitted?

Answer 3

Horizontal transmission - saliva, nasal secretions, milk, urine, feces (close contact, bites)
Vertical transmission - in utero, nursing

Question 4

Describe the pathogenesis FeLV infection.

Answer 4

Typically acquired through oronasal exposure -> viral replication in local lymphoid tissues of oropharynx -> monocytes & lymphocytes infected -> goes to circulation -> primary viremia (lasting 3-6 weeks) -> viral replication in bone marrow -> secondary viremia that is associated with progressive infection

Question 5

When is FeLV detectable by IFA?

Answer 5

30 days after exposure

Question 6

What are the 3 possible outcomes of exposure to FeLV?

Answer 6

1. Progressive infection
2. Regressive infection
3. Abortive infection

Question 7

Which outcome of exposure to FeLV is associated with persistent viremia & shorter survival time?

Answer 7

Progressive infection

Question 8

T/F: There are low to undetectable levels of neutralizing antibodies in cats with progressive infection of FeLV.

Answer 8

T

Question 9

With progressive infection of FeLV, state if the test would be positive or negative:
POC FeLV test, PCR, & IFA

Answer 9

POC FeLV - positive (unless very early infection)
PCR - positive & in high numbers
IFA - ONLY POSITIVE W/ PROGRESSIVE (indicates bone marrow involvement)

Question 10

Which outcome of exposure to FeLV is associated with transient viremia?

Answer 10

Regressive infection

Question 11

Which outcome of exposure to FeLV does not lead to viremia?

Answer 11

Abortive infection

Question 12

With regressive infection of FeLV, state if the test would be positive or negative:
POC FeLV test, PCR, & IFA

Answer 12

POC FeLV - can be positive in first 16 weeks of infection
PCR - can be positive OR negative (if positive should be lower in #s)
IFA - negative!

Question 13

T/F: Abortive infection associated with FeLV does not develop viremia, and therefore won’t have any detectable antibodies.

Answer 13

F - do have detectable antibodies

Question 14

With abortive progression of FeLV, state if the following tests will be positive or negative:
POC FeLV test, PCR, & IFA

Answer 14

POC FeLV - negative
PCR - negative
IFA - negative (duh)

Question 15

What is the most common hematologic abnormality you will find on CBC of a cat with FeLV?

Answer 15

Macrocytic, non-regenerative anemia (sometimes pancytopenia)

Question 16

What are the most common neoplasias associated with FeLV?

Answer 16

Lymphoma & leukemia

Question 17

T/F: FeLV antigen test negative in most cats with lymphoma

Answer 17

T

Question 18

In regards to FeLV associated lymphoma, mediastinal/alimentary (choose one) is associated with positive FeLV status, whereas mediastinal/alimentary (choose one) is not associated with it.

Answer 18

Mediastinal, alimentary

Question 19

An ELISA FeLV/FIV antigen test will appear positive within how long of infection?

Answer 19

Within 4 weeks

Question 20

You receive a positive FeLV ELISA SNAP test. What should you do next?

Answer 20

Repeat the ELISA (either in house or send it out to confirm)

Question 21

T/F: Regressive cats may be positive on ELISA during transient viremia but should be negative within 16 weeks of infection.

Answer 21

T

Question 22

What does a positive FeLV ELISA test mean?

Answer 22

It is either progressive or regressive infection

Question 23

A cat is positive for FeLV on ELISA but had a negative IFA. What is your interpretation?

Answer 23

• Transient viremia (regressive infection)
• Early, before bone marrow infection in progressive infection
• Low level cell associated viremia (cytopenia)
• False positive (rare)

Question 24

How do you treat a cat with FeLV?

Answer 24

You don’t
You can only treat the associated diseases

Question 25

T/F: FeLV vaccination does not cause + FeLV test, but FIV vaccination does cause + FIV test.

Answer 25

T

Question 26

Which cats are at greatest risk for FIV?

Answer 26

Male, outdoor cats

Question 27

How is FIV transmitted?

Answer 27

• BITE WOUNDS
• Possible transplacental/nursing but uncommon

Uncommon in cats living together without fighting

Question 28

T/F: Neoplasia is 5x more common in cats with FIV.

Answer 28

T

Question 29

What are the clinical signs associated with FIV?

Answer 29

• Transient/mild or inapparent in initial stage
• Some may have no clinical signs at all
• Chronic infections get immunosuppression (recurrent infections, stomatitis)

Question 30

What laboratory findings do you expect to see in a cat with FIV?

Answer 30

CBC - neutropenia, lymphopenia, anemia
Chemistry - hyperglobulinemia

Question 31

Does the ELISA SNAP test look for antigen or antibodies to FIV?

Answer 31

Antibodies

Question 32

What antibody tests can we use to detect FIV?

Answer 32

ELISA or Western blot (gold standard for FIV antibodies)

Question 33

You run an FeLV/FIV test on a cat & it shows up positive for FIV. What is your interpretation?

Answer 33

• Truly infected (most cases)
• Vaccination
• False positive
• Maternal antibodies (up to 6mo of age)

Question 34

If you run an FeLV/FIV test and it shows up negative for FIV but you are still suspicious, what are you going to do?

Answer 34

Could consider western blot test and/or retest no sooner than 60 days

Question 35

An 8-week old kitten presents to you for a first visit. No previous history. What do you recommend in terms of FeLV/FIV testing & vaccination?

Answer 35

Recommend all kittens be tested for FeLV/FIV & vaccinated for FeLV no matter what lifestyle they have