Causes immunodeficiencies,
malignancies, anaemias and
degenerative responses.
Oncogenic retroviruses
Rapidly transforming=
v-onc gene in genome (in
place of capsule gene)
Slowly transforming=
Provirus inserted into
DNA next to c-onc gene
RNA is converted to the
DNA provirus by reverse
transcriptase.
RT enzyme is highly error prone and
they lack proof reading capability.
This allows rapid mutation and lets
them evade the hosts immune system,
they also are able to infect the cells of
the immune system and integrate
themselves into the host DNA
They are transmitted horizontally or
vertically and are very host specific. If
the virus is endogenous it means the
provirus has been inserted intot eh
host DNA.
Lentiviruses
Nota:
Transmission by body fluids
Control by eradication
They have long incubation periods and form persistent infections with a specific tropism for lymphocytes and monocytes.
Visna (wasting) and Maedi (dyspnea)
They have long incubation
periods, and show general
signs of weight loss.
Caprine arthritis encephalomyelitis (goats)
Infection by mammary
Leukoencephalomyelitis
common in kids 2-4months
old.
Arthritis is the more common
form of the disease, in adults
over 12months old.
FIV
Nota:
More common in NZ than FeLV
There is a long asymptomatic period followed (sometimes) by fever, anaemia, weight loss and behavioural changes.
The late stages resemble human AIDs.
Transmitted by bite wounds
(infection more common in male cats)
Control by vaccine, and anti-retroviral drugs.
TSE's
Nota:
Normal protein folds incorrectly due to the coercion from the pPrP version. pPrP then accumulates in the cell and eventually kills it. pPrP is less soluble and more resistant to proteases than the normal one.
They are extremely resistant to everything, to kill them you have to autoclave with NaOH.
Possible ways they occur is through Ingestion, Inheritance or De Novo.
Pathological findings include fibrils and holes in the brain.
BSE
Transmission risks are
mainly from food products.
There can be risk from blood
donations to humans as
well.
Scrapie
By breeding resistant animals you are
breeding ones with PrPc that is not
alike to the PrPsc
Creutzdelft-Jakob disease
Classical
Sporadic - most common
Hereditary - 2nd most common.
Inherited disease
Iatrogenic - least
common.
Transmission through
medication
New form. Longer duration
of illness linked to
exposure through food.
Caliciviruses
Nota:
Hardy (inactivated at pH 3)
Small, non-enveloped, RNA.
Vesicular exanthema of swine
Nota:
Causes lesions on the muzzle, abortions, diarrhoea. Low mortality.
Solid immunity with no cross protection.
In sea lions too.
Important DDx for FMD, but
this one effects pigs and
horses but not cattle.
Rabbit calicivirus
Nota:
Faecal oral infection,
Peracute disease with short incubation period followed by rapid death in 100% of adult rabbits.
Rabbits under 2months old not killed.
Nota:
They may lack the mechanisms to initiate the clotting,
Lack the receptors that allow the virus to effect hepatocytes.
Prevention by vaccines
Feline calicivirus
Nota:
Common of young cats, they have long term immunity after recovery.
It is moderately stable in the environment and shed in large amounts in respiratory secretions and faeces.