RETROVIRIDAE. Part I- RETROVIRUSES

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RETROVIRIDAE. Part I- RETROVIRUSES

• PETER H. RUSSELL, BVSc, PhD, FRCPath, MRCVS
• Department of Pathology and Infectious Diseases,
  The Royal Veterinary College,
• Royal College Street,
• London NW1 OTU.
• E-mail Web site

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ObjectiveStudents should be able to

• define the importance of reverse transcriptase in
  replication and chromosomal integration.
• explain subgroup, endogenous viruses, oncogenes
  and transformation, how lability leads to either
  horizontal transmission by close contact/blood or
  vertical transmission.
• describe the clinical signs of FeLV, the
  diagnostic ELISA test for FeLV and test and
  removal schemes.
• describe in outline the pathogenesis and control
  of Bovine Leukosis virus and sheep Pulmonary
  Adenomatosis

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Classification of Retroviridae

• the genera include these veterinary viruses

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STRUCTURE
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Physicochemical properties

• The virus only survives for a few hours outside
  the host.
• Small amounts of virus are excreted by the host
  and infection requires either close contact, e.g.
  mutual grooming, blood transfer or vertical
  transmission (see later)

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Transformation and oncogenesis
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Transfection, Research
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Detection

• Because leukaemia viruses cause no cytopathic
  effect in tissue culture they have been detected
  by EM or by IIF .

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Cell tropism in vivo

• They grow in rapidly-dividing cells eg bone
  marrow.

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FELINE LEUKAEMIA VIRUS (FeLV)

• FeLV is one causative agent of feline
  lymphosarcoma and leukaemia, which are the most
  important and common tumours of cats. The same
  tumours sometimes occur without FeLV,
  particularly in cats aged over 7 years.

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FELINE LEUKAEMIA VIRUS (FeLV)

• Pathogenesis

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FELINE LEUKAEMIA VIRUS (FeLV)

• Clinical signs

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FELINE LEUKAEMIA VIRUS (FeLV)

• Epidemiology

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FELINE LEUKAEMIA VIRUS (FeLV)

• Diagnosis of FeLV

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FELINE LEUKAEMIA VIRUS (FeLV)

• Control

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SHEEP PULMONARY ADENOMATOSIS (SPA)

• Virus Retrovirus particles can be seen by EM in
  the tumour cells of affected sheep. The virus
  cannot be grown in culture.

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SHEEP PULMONARY ADENOMATOSIS (SPA)

• DiagnosisNo serological test nor virus isolation
  is possible. Clinical symptoms. Nasal fluid
  discharges when the sheep is up-ended (the
  wheelbarrow test). At post mortem the tumour is
  fawn-grey in colour but may be obscured by
  secondary infection with oedema and/or pneumonia.

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AVIAN LEUKOSIS VIRUS
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BOVINE LEUKOSIS VIRUS (BLV)

• Notifiable disease.