88. Feline leucosis and acquired immune deficiency of cats.

Question 1

Feline leukosis Occurence?

Answer 1

Feline leukosis Susceptible: Domestic and wild cat, felidae

Retroviridae, Orthoretrovirinae, Gammaretrovirus, Feline leukosis virus (FeLV)

• Occurrence: widespread infection, USA (catteries 80-100%, outgoing cats 25-60%, indoor, alone 5-6%), Europe
• Sharp decrease in recent years due to vaccination/testing/eradication! -
• Invidiual cats = 1 % Cattery = 20 %

Question 2

Etiology of Feline leukosis?

Answer 2

Etiology:

• Related to mouse leukemia virus
• 4 Subgroups (A, B, C, T subgroups), only subgroup A viruses can infect cats, B-C-T subgroups (defected
• virus ʹ cannot replicate on their own) were evolved from subgroup A, need helper virus ʹ differences in
• cell preference and pathology
• FeLV-A: predominant subgroup, in all FeLV-infected cats
• FeLV-B: recombination FeLV-A env-gen and endogenous proviral DNA, together with FeLV-A higher risk of tumor
• FeLV-C: mutation in the FeLV-A env-gen, erythroid hypoplasia, fatal anemia, not transmitted
• FeLV-T: mutations envelope protein, T cell tropic - immunosuppression
• Surface protein:
• 27kDa group specific: appears in soluble form (can find in blood!)
• 70kDa surface glycoprotein: entrance, VN
• 15kDa: trans-membrane protein - immunosuppression
• Resistance: low in environment
• Feline sarcoma virus: recombination of feline leucosis virus and host DNA, defective virus,
• replication only together with feline leucosis virus, tumor transformation,fibrosarcoma

Question 3

Epidemiology of feline leukosis?

Answer 3

Epidemiology

• Horizontal: spreading in saliva, discharges: high titre in saliva, tear, urine, feces
• Direct contact (need long time): nose-to-nose, shared plate, licking, grooming, bite, scratch
• Vertical: intrauterine
• immunotolerance/abortion, milk, saliva of mom
• Connection with population density: catteries (80-100% infected, 30-50% persistent), outdoor
• cats 25-60% infected, 1-2% persistent
• Cattery > outdoor > indoor
• Maintained by persistently infected cats: persistently infected cat has persistently infected kitten
• (intra-uterine infection, milk)
• All age groups are susceptible: most frequent 2-4-year old cats, young are more susceptible
• Maternal protection: 2 months
• Asymptomatic infection

Question 4

Pathogenesis of feline leukosis?

Answer 4

Pathogenesis

• Infection PO (aerogenic)
• replicate in Tonsils, LN
• Viremia (immunity can prevent, if good
• immunity wont have viraemia, Replication in lymphoreticular and hemopoietic cells
• Replication: MM, salivary gland
• Protective immunity (abortive): elimination of the virus, asymtomatic, no carriage
• Limited immunity (regressive): transient viremia, asymptomatic, latency in bone marrow, virus is eliminated later
• No immunity (progressive): persistent infection, viremia, clinical signs
• Non-tumor clinical signs:
• immunosuppression, anemia, enteritis, reproduction disorders, immune complex (Atg + Atb deposit in joints/BV/kidney Æ vasculitis, glomerulonephritis, arthritis)
• Tumor clinical signs:
• MOST: lymphoid leucosis, myeloid leucosis,sarcomatosis
• On the surface of the tumor cells: FOCMA (feline oncornavirus associated cell membrane antigen)
• Can detect this
• Shedding 1-16 weeks (70% of cats)

Question 5

Clinical signs of feline leukosis?

Answer 5

Clinical signs

• Incubation 4-6 weeks
• Fever, depression, anorexia (viremia), weightloss, returning fever, diarrhea
• tumor (25%)
• Lymphosarcomatosis: diarrhea, respiratory signs, infertility
• Myeloproliferative leucosis: anemia, enlarged spleen, liver
• Persistent infection: autoimmune hemolytic anemia, glomerulonephritis
• Complications due to immunosuppression: toxoplasmosis, M. hemofelis

Question 6

Pathology of feline leukosis?

Answer 6

Pathology:

• cachexia,
• anemia,
• enlarged liver/spleen/LN,
• tumors in different organs (thymus, gut lymphoma)

Question 7

Diagnosis of feline leukosis?

Answer 7

Diagnosis:

• clinical signs and PM lesions
• Histology, cytology (biopsy, thoracic fluid)
• Detection of virus/antigen: PCR (p27, p70), IF (WBC p27), ELISA ;(dissolved P27)(dont really use isolation)
• use isolation)
• Detection of FOCMA (Fe oncornavirus associated cell membrane antigen): IF, ELISA
• No diagnostic value, should do 3-4 months later (persistent infection)
• Detection of antibodies: iIF, VN, ELISA
• Chromatography ʹ rapid tests!
• Detection of virus and the antigens have to be repeated in 3-4months

Question 8

Treatment of feline leukosis?

Answer 8

Treatment:

• Prevention of secondary infections of infected cats: vaccination, antiparasitic treatment, keeping
• indoor, treatment of secondary diseases
• Supportive therapy
• Viremia cannot be influenced (antiviral treatment ʹ very costly)
• Treatment of cats showing clinical signs is hopeless
• Cytotoxic treatment (cyclophosphamid, AZT azido-timin): prolong life, 50% clinical recovery,some don’t react

Question 9

Prevention and public health aspects?

Answer 9

Prevention:

• isolation of infected
• Inactivated, subunit, vector vaccines: prevention only of clinical signs, vaccination of only
• seronegative cats (stops in viremic phase, better immune response), all healthy cats
• have to be vaccinated in infected areas
• After mat abts: 8-9 week: 1st vaccination > 12 weeks: 2nd vaccination > yearly until 3
• year old > every 2-3 year after
• Serological survey is recommended in case of first examination by a vet, introduction of cats into a
• disease-free herd, introduction of free cat to a herd of unknown state of infection, before
• vaccinating against fe-leukosis
• Eradication: test and remove policy

Public health aspects:

• some strains able to replicate in human tissue cultures,
• but NO zoonotic risk

Question 10

Acquired immune deficiency of cats Occurence ethiology?

Answer 10

Acquired immune deficiency disease of cats Susceptible: ONLY cats (felidae)

• Retroviridae, Orthoretrovirinae, Lentivirus, Feline immune deficiency virus (FIV)

Occurrence:

• widespread, more frequent in cats sufferring from other diseases

Etiology:

• Several types: A, B, C, D, E subtypes ʹ geographic variation
• Variants in the subtypes, no cross protection!
• Replication on cat cell cultures
• Good antigen

Question 11

Acquired immune deficiency of cats Epidemiology?

Answer 11

Epidemiology

• Mainly in cats older than 2 years, outdoor cats, males,fighting
• Horizontal infection: discharges, blood, saliva (hi titre!), iatrogenic infection
• Vertical infection: intra uterine, colostral
• immunotolerance if Intrauterine
• Long carriage
• Clinical signs only in a part of the cats

Question 12

Acquired immune deficiency of cats Clinical signs?

Answer 12

Clinical signs

• Acute: 3-6 months Subclinial: month ʹ year Chronic: month ʹ year
• Viaraemic phase: fever, depression, anorexia, lymph nodes enlarged (maybe even asymptomatic)
• Persistent viaraemia phase: fever, anaemia, rhinitis, conjunctivitis, stomatitis, gingivitis, tumours,
• complications, slow, long lasting, death

Question 13

Diagnosis, treatment and prevention/control of acquired immune deficiency of cats?

Answer 13

Diagnosis

• Epidemiology ʹ clinical signs ʹ post mortem examination
• Lab: lymphopenia, anaemia
• Detection of the agent: detection of the virus (PCR), isolation of the virus (lymphoid cells)
• Detection of antibodies: ELISA, iIF, blot

Treatment:

• cannot be treated / anti-HIV medicines, corticosteroids
• Complications: antibacterial medicines

Prevention, control:

• isolate infected animals, import QT