FeLV & FIV

Question 1

What type of virus are FeLV and FIV and what does this mean?

Answer 1

Retroviruses- they’re enveloped single stranded RNA

Question 2

What are FeLV and FIV differential diagnosis’ for?

Answer 2

Immunosuppression- so if you suspect one you always test for both

Question 3

What protein is the basis of many FeLV diagnostic tests?

Answer 3

Capsid protein p27- produced by the virus within infected cells [detected by diagnostic tests]

Question 4

What is the role of the surface glycoprotein on the FeLV virus?

Answer 4

Defines the subgroup and is the target for vaccination

Question 5

What is the role of the P15E transmembrane protein on FeLV viruses?

Answer 5

causes immunosuppression in the host

Question 6

Once FeLV has integrated into the host DNA within a cell, what 3 mechanisms can occur?

Answer 6

• destruction of virus infected cell by the immune response
• infection with/ without virus production
• transformation to tumour cell

Question 7

What do we mean by a regressor cat/ abortive infection?

Answer 7

Infected with FeLV initially but has effectively eliminated the virus and gained lifelong immunity

Question 8

What do we mean by regressive infected FeLV cat?

Answer 8

they carry FeLV DNA in their bone marrow- at this point they’re not infective for other cats BUT the virus may be reactivated at some point at which point they may begin to show clinical signs and become a source of infection for other cats

Question 9

What is a focal/ atypical infection of FeLV?

Answer 9

when the cat’s immune system keeps virus replication sequestered to certain tissues- will test negative if not sampled from these tissues

Question 10

What are the four types of FeLV pathogenesis infections and do these cats test positive or negative for FeLV?

Answer 10

Abortive- test negative
Regressive- test positive (but not infectious mostly)
Focal/ Atypical- test negative unless taken from specific tissues
Progressive- test positive

Question 11

Where does FeLV replicate?

Answer 11

Replicates in the local lymphoid tissues before systemic spread to bone marrow

Question 12

Where does FeLV populate?

Answer 12

populates salivary glands and mucosal glandular epithelium (hence why it spread via saliva and nasal secretions)

Question 13

What are the signs of FeLV in a progressively infected cat?

Answer 13

Immunosuppression- lots of secondary infections
Neoplasia (mainly lymphoma)
Bone marrow disorders

Question 14

When do bone marrow disorders as a result of FeLV develop?

Answer 14

when the virus infects haematopoietic stem cells and stromal cells

Question 15

What 5 diagnostic tests can we do to diagnose FeLV?

Answer 15

ELISA detection of P27
Immunofluorescence for antigen inside infected cells
PCR for FeLV RNA
Viral Culture
Testing for neutralizing antibody

Question 16

What is the first line option for diagnosis of FeLV?

Answer 16

ELISA detection of P27 antigen using serum (some false positives associated with plasma/whole blood)

Question 17

When can we test kittens with an ELISA detection of P27?

Answer 17

Anytime- because we’re testing antigen presence

Question 18

After we have used the first line diagnostic test for FeLV (ELISA) what do we do next?

Answer 18

Confirmatory tests (the other 4 available)

Question 19

What is good about PCR for FeLV RNA?

Answer 19

Can confirm if the infection is progressive or regressive

Question 20

What is the prognosis of cats with FeLV?

Answer 20

Good if no lymphoma development- approx 2.5 years

Question 21

How can we prevent FeLV infection?

Answer 21

only introduce negative cats into the household- consider keeping them indoors unless they’re vaccinated

Question 22

Is there an FeLV vaccine available in the UK? Is it always used?

Answer 22

Yes- 5 types licensed but only used based on risk of exposure as it can cause injection site sarcomas

Question 23

When can we test kittens for FeLV?

Answer 23

at 6 weeks of age- but good practice to do 2 tests

Question 24

What cells does FIV infect?

Answer 24

CD4+ T cells, B cells and activated macrophages

Question 25

What is unique about the envelope of FIV?

Answer 25

It’s derived from the host cell

Question 26

Which groups are most at risk of FIV?

Answer 26

male, aggressive, free roaming cats

Question 27

What are the most common clinical findings in a cat with FIV? (5)

Answer 27

Gingivostomatitis
Neoplasia
Ocular signs such as Uveitis
Anaemia
Chronic Kidney disease

Question 28

When is an FIV test indicated? (5)

Answer 28

Sick cats- particularly those with anaemia, or those infected with mycoplasma
Cats that are being rehomed
Kittens from FIV+ queens
Cats with bite wounds
Cats living with an FIV+ cat

Question 29

What is the first line test used for FIV diagnosis? What is the confirmatory test?

Answer 29

1st line- ELISA of FIV antibody
Confirmatory- Western blot or Immunofluorescence assay

Question 30

If a cat has previously lived abroad and its medical history unknown- can we use an ELISA to test for FIV?
What’s the alternative?

Answer 30

Not really- UK doesn’t vaccinate for FIV but other countries do and ELISA doesn’t differentiate between vaccinated and infected- only a PCR of FIV RNA can differentiate

Question 31

A positive FIV serology result (ELISA) means… (2)

Answer 31

• Cat is infected with FIV
• Cat has circulating maternal antibodies- need to retest older than 6 months old

Question 32

A negative FIV serology result (ELISA) means… (3)

Answer 32

• Cat is not infected
• Cat is infected but hasn’t generated an immune response yet- retest in 60 days
• Disease is terminal and antibody production has fallen due to immunosuppression

Question 33

Does an FIV positive diagnosis affect survival time?

Answer 33

NO

Question 34

How do we treat a systemically sick FIV cat?

Answer 34

bacterial antibiotics
possibly use glucocorticoids

Question 35

When do we test kittens who have come from an FIV+ queen?

Answer 35

Can test at 16 weeks and then retest 6 weeks later but vertical transmission unlikely