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

FELINE LEUKEMIA VIRUS Zarah Hedge, DVM

Chelsea Reinhard, DVM

FELV OVERVIEW

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

FELV OVERVIEW

Young kittens most susceptible 1-8% prevalence worldwide

Declined over past 25 years Median survival time: 2.4 years

FELV CLINICAL PICTURE

Tumors Immunosuppression

Concurrent disease Hematologic (blood) disorders Immune-mediated disease Many more...

INFECTION

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

PATHOGENESIS

Exposure

Regressor cat

Transient viremia

viremia

days

Latent infection

lifelong

3-13 wk

3 wk

Stress or immunosuppression

FELV DIAGNOSTICS

Screening test ELISA

Confirmatory tests IFA PCR

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

IFA

Detects p27 Ag

• More prone to false negative results than ELISA

PATHOGENESIS

Exposure

Regressor cat

Transient viremia

viremia

days

Latent infection

lifelong

3-13 wk

3 wk

Stress or immunosuppression

ELISA +

ELISA +

IFA +

PCR

FELV DIAGNOSTIC TESTING

PCR (?) Supposed to detect viral DNA in the cat’s

genome Testing protocols not standardized or validated

CONFUSION!

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

QUESTIONS?