1. F ELINE L EUKEMIA V IRUS Zarah Hedge, DVM Chelsea Reinhard, DVM

2. F E LV O VERVIEW Retrovirus  Oncornavirus subfamily First discovered in the 1960s Enveloped ssRNA with protein core Transmission Typically oro-nasal route Close contact  social behaviors Saliva* Other secretions (feces, urine) – less common “Friendly cat” transmission Transplacental &/or via milk, close contact

3. F E LV O VERVIEW Young kittens most susceptible 1-8% prevalence worldwide Declined over past 25 years Median survival time: 2.4 years

4. F E LV C LINICAL P ICTURE Tumors Immunosuppression Concurrent disease Hematologic (blood) disorders Immune-mediated disease Many more...

5. I NFECTION Progressive = Lifelong FeLV is not contained early in infection Virus replication in lymphoid tissue (lymph nodes), bone marrow, other tissues Cats with progressive disease succumb to FeLV- associated illness within a few years Regressive Immune response that contains virus before/at the time of bone marrow infection Transient Low risk of developing FeLV-associated illness

6. P ATHOGENESIS Exposure Regressor cat Transient viremia viremia days Latent infection lifelong 3-13 wk 3 wk Stress or immunosuppression

7. F E LV D IAGNOSTICS Screening test ELISA Confirmatory tests IFA PCR

8. Detects free FeLV p27 (core protein) Ag in plasma or serum *recommended screening test* Most cats will test positive within 30 days of exposure False + Whole blood (hemolyzed) False – rare

9. IFA Detects p27 Ag More prone to false negative results than ELISA

10. P ATHOGENESIS Exposure Regressor cat Transient viremia viremia days Latent infection lifelong 3-13 wk 3 wk Stress or immunosuppression ELISA + IFA + PCR

11. F E LV D IAGNOSTIC T ESTING PCR (?) Supposed to detect viral DNA in the cat’s genome Testing protocols not standardized or validated

12. C ONFUSION ! Detection = CONFUSING Discordant test results may be due to the stage of infection Reasons can include cats that resist bone marrow infection and cats that have regressive infections Repeat both tests (ELISA and IFA) in 30 days

14. Q UESTIONS ?