Category:Secondary Immunodeficiency

• There are many causes of secondary immunodeficiency
  • Most deficiencies are not genetic
  • Most are agent-induced, such as from X-ray radiation and immunosuppressive drugs

Viral Causes

Feline Leukaemia Virus (FeLV)

FeLV Electron Micrograph Public Health Image Library Image #5610

Kinetics of FeLV - Copyright Dr Brian Catchpole BVetMed PhD MRCVS

• Oncogenic retrovirus
• Causes neoplasia (lymphoma), myelosuppression (anaemia) and immunosuppression (of T cells)
• 2 strains:
  • FeLV-A
    • Natural strain
  • FeLV-B
    • Formed through FeLV-A recombining with endogenous retroviral sequences in the feline genome
    • Increases the risks of lymphoma
  • FeLV-C
    • Formed from the spontaneous mutation of FeLV-A
    • Is more myelosuppressive
• Virus replicates in the oropharyngeal lymphoid tissue causing a viraemia (virus circulating in the bloodstream) which then spreads to the systemic lymphoid tissue
• Shed in saliva
• Passed by oronasal route, e.g. mutual grooming
• Kittens between 6 weeks and 6 months are most susceptible
• 60% of cats will become immune to the disease and recover
• Cats that are persistently viraemic will progress to develop FeLV-associated diseases
• Some cats will become viraemic again if treated with corticosteroids or stressed if the infection lies dormant in the bone marrow
• Diagnosis:
  • ELISA
  • Rapid-Immuno-Migration
  • Western Blot
  • Virus Isolation
  • Immunofluorescence
  • PCR
• Treatment:
  • Antibiotics for secondary infection
  • Anti-retroviral therapy
• For vaccinations see here

Feline Immunodeficiency Virus (FIV)

• Lentivirus
• Subtypes A, B and D
• Causes increased susceptibility to infections and neoplasia
• Specifically destroys CD4+ T cells
• Virus is present in saliva, blood and other bodily fluids
• Feral and outdoor cats (mostly tom cats) are most at risk
• Virus replicates in lymphoid tissue
• Can remain asymptomatic
• Causes pyrexia and lymphadenopathy
• Transmitted by biting
• Diagnosis:
  • ELISA
  • Rapid-Immuno-Migration
  • Western Blot
  • Virus Isolation
  • Immunofluorescence
  • PCR
• Treatment:
  • Antibiotics for secondary infection
  • Anti-retroviral therapy
• For vaccinations see here

Bovine Immunodeficiency Virus (BIV)

• Lentivirus (non-oncogenic)
• Causes a persistent viral infection and lymphocytosis
• Immunocompromised cattle may develop secondary infections
• The transmission is not well known, but the following possibilities are being researched:
  • Through milk
  • Through infected semen (e.g.artificial insemination)
  • Placental transfer
• Diagnosis:
  • Western Blot
  • PCR

Toxic Causes

• Poisons

Iatrogenic Causes

• Drugs
  • Corticosteroids
  • Cyclosporin
  • Cytotoxic cancer therapy

Other Causes

• Malnutrition

• Chronic disease

• Stress

• Senescence