Download HERPESVIRIDAE

RETROVIRIDAE.
Part IRETROVIRUSES
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
Objective
Students 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
Classification of Retroviridae
the genera include
veterinary viruses:
these
STRUCTURE
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)
Transformation and
oncogenesis
Transfection, Research:
Detection
Because leukaemia viruses cause no
cytopathic effect in tissue culture they
have been detected by EM or by IIF .
Cell tropism in vivo:
They grow in rapidly-dividing cells eg
bone marrow.
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.
FELINE LEUKAEMIA VIRUS
(FeLV)
Pathogenesis:
FELINE LEUKAEMIA VIRUS
(FeLV)
Clinical signs:
FELINE LEUKAEMIA VIRUS
(FeLV)
Epidemiology:
FELINE LEUKAEMIA VIRUS
(FeLV)
Diagnosis of FeLV:
FELINE LEUKAEMIA VIRUS
(FeLV)
Control:
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.
SHEEP PULMONARY
ADENOMATOSIS (SPA)
Diagnosis:No 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.
AVIAN LEUKOSIS VIRUS
BOVINE LEUKOSIS VIRUS
(BLV)
Notifiable disease.