Lecture 7; small ruminant viral infections Flashcards
what is it meant by virus induced transformation?
a virus has changed a normal cells into a tumor cell- these viruses are oncogenic viruses
give 4 examples of oncogenic DNA viruses, and where do they disrupt the cell cycle
- pox 2. herpes 3. adeno 4. papilloma
DNA oncogenic viruses interrupt the cell cylce at the start just after M because the encode inhibitors of tumor suppressor genes
give 2 examples of RNA oncogenic viruses and where do they interrupt the cell cycle
- retro 2. flavi
RNA oncogenic viruses encode homologs of oncoporteins so they act on the point of no return in G1
The contagious lung tumor condition caused by Jaagsiekte retrovirus (JSRV) is called
Ovine pulmonary adenocarcinoma
what 2 countries are free of OPA?
Australia and iceland
what age are you going to see most clinical cases of OPA
3-4 year olds, rare in sheep under 7-9 months of age
is OPA fatal?
yes, once clinical signs appear this disease is always fatal
how is JSRV transmitted
respiratory route- aerosols or droplets (transmitted even by sub clinical animals) also through milk and colostrum
describe the pathogenesis of OPA
- infection via inhalation of virus 2. the epithelial cells of the lung are infected 3. virus is expressed and shed 4. transformation 5. tumor growth and spreads to the lymphnodes 6. death
what is the incubation period for OPA
6-36 months
what cells within the lung are transformed by JSRV
Type II pneumocytes are the majority, then club cells, then undifferentiated cells
what will you see pathologically with OPA
frothy fluid filled trachea
intersitial pneumonia appearance
tumors
secondary abscessation
bronchial and mediastinal lymph nodes are often enlarged
what are the clinical signs of OPA
fever cough dyspena frothy mucoid discharge (us the wheelbarrow test to check for extra fluid in the lungs)
can you dx OPA? why or not why not?
Not with certainty- there will be lots of secondary bacterial infections, and antibodies are not detected in the sera- you may be able to detect through RT PCR of the bronchoalveolar cells
what is the treatment option for OPA
Culling is really the only option- if vx is attempted it can induce autoimmune inflammatory response in the reproductive track and then break any tolerance they did have to the disease
what is OPP and what virus causes it?
OVINE PULMONARY PNEUMONIA caused by maedi visna virus (retrovirus)
how can a producer avoid OPA infection?
its hard- you cannot detect the subclinical animals and that is usually how it is introduced into a flock. make sure to get sheep from a farm with no hx of OPA and quarantine could be an option but again the incubation period is 6-36 months (not practical), mayne hand rear lambs, and have single aged flocks
what are the signs and symptoms of OPP, how is it transmitted
dyspnea, neuro signs, poor milk production due to mastitis
transmitted via respiratory colostrum and sexual
what cells are infected by OPP
macrophages and dendritic cells
what gross lesions of the lung will you see with OPP
lungs that fail to deflate and contain coalescing multifocal gray nodules with adjacent atelecatic depressed parenchyma
what clinical signs will you see with MVV infection
visna (neuro); brain and spinal cord infection, hind limb weakness ataxia, paresis and paralysis
maedi (dyspnea); arthritis, mastitis in addition to the resp involvement
how would you dx and control OPP
DX; AGID- WESTERN blotting, RT- PCR
to control you can remove kids and lambs before they are fed colostrum but it can also be passed transplacental so that doesnt helo there
what s CAE? what are its symptoms/ syndromes?
caprine arthritis and enceophalitis, it causes polyarthritis in adults and encephalomyelitis in kids, also causes indurative mastitis (hard udder) and decreases milk production, as well as chronic interstitial pneumonia
how is CAE transmitted? by what virus? what cells are targeted
carprine arthritis and encephalitis is caused by infection of the CAE virus and is transmitted by vertical transmission via colostrum and milk, it targets macrophages and DC and synovial membrane cells
clinically, what would you see in a goat that is infected by CAEV
edmatous thickening of the joints, chronic intersitial pneumonia, hard udder
youre presented with a young kid that is ataxic and cannot move its hindlimbs, what is most likely OPA OPP or CAE
CAE
how do you dx CAE, control?
AGID test, ELISA
no vx, no cure, prevent vertical transmission
what is orf?
contagious ecthyma of sheep, caused by the orf virus (parapoxvius)
what are the clinical symptoms of Orf? whats important to remember
orf is ZOONOTIC! causes scappy lesions around the mouth and nose, spread through direct contact or fomites
what is the incubation period of Orf, is it fatal?
2-3 days, no uncomplicated infections resolve in 1-4 weeks it has high morbidity low mortality
what cells are targeted with orf virus
epitheliotropic virus targets epidermal keratinocytes
would you reccomend the orf vx?
no- it causes infection, spreads infection, and does not provide long lasting immunity (year long max)
what is blue tongue, which animal is the main reservoir?
caused by the blue tongue virus it infects sheep cattle deer goats and camelids and cows are the mammalain resivores transmitted by culicoides
what are the clinical signs of blue tongue in sheep
high temp, eye and nasal discharge, ulcers in the mouth, swelling of the mouth head a neck, lameness with inflammed coranary band, abortion, trouble breathing
true or false, cattle that are persistently infected with one strain og BTV will show symptoms
false; they will not shoe clinical signs until they are infected with an additional strain and then you may see ulcers in the mouth nose and udder along with lameness and swollen tongue
