lecture 8- small ruminant virology Flashcards
what is it called when viruses have the ability to change a normal cell into a tumor cell? what are these viruses referred to as
transformation
oncogenic viruses
what are the 2 groups of tumor genes
proto oncogenes
tumor suppressor genes
what are the oncogene DNA viruses (6)? what do they encode?
what part of the cell cycle do they affect?
pox
herpes
adeno
papilloma
polyoma
depadna
encode inhibitors of tumor suppressor genes
affects the end of M / beginning of G1
what are the oncogene RNA viruses (2)? what do they encode?
what part of the cell cycle do they affect?
retro
flavi
encode homologs of oncoproteins
between G1 and S phase
what is JSRV? What does it cause?
Jaagsiekte sheep retrovirus
the agent that causes ovine pulmonary adenocarcinoma
what is OPA
ovine pulmonary adenocarcinoma
what cells does ovine pulmonary adenocarcinoma (OPA) target?
epithelial cells of bronchioli and alveoli (type 2 pneumocytes), lymphocytes, myeloid cells
what is JSRVs (Jaagsiekte sheep retrovirus) mechanism of action?
is a retrovirus and carries and oncogene (inserts into host genome)
it is a ssRNA-RT
what is the structure of JSRV? (Jaagsiekte sheep retrovirus)
enveloped, positive sense
what is the geographical distribution of ovine pulmonary adenocarcinoma (OPA)/JSRV
everywhere but australia, iceland and new zealand
at what age are most animals infected with JSRV?
over 2 years, peak at 3-4 years
is JSRV always fatal once clinical signs appear?
yes
how is JSRV transmitted?
respiratory (aerosole/droplets), milk/colostrum
once infected with JSRV, can sheep get rid of the virus?
no! retrovirus so carriers for life
what are the clinical manifestations of OPA/JSRV
fever, cough, dyspnea;
chronic resp signs (2-4 YO
animals) with frothy mucoid
discharge from nostrils
if a sheep is infected with JSRV/OPA, what will be seen on histo
proliferating type 2 pneumocytes
what will be seen grossly with OPA on necropsy?
frothy fluid filling trachea/nares
enlarged, edematous lunge that fail to collapse (interstitial pneumonia)
focal to diffuse bulky mass (tumors)
enlarged lymph nodes
explain how the wheel barrow test might help with diagnosing OPA
raising hind legs will cause excess lung fluid to drain from nose/mouth.
this is because type 2 pneumocytes are proliferating, thus producing toooooo much surfactant (yuck)
why is there not a vaccine for JSRV?
approx 20 copies of endogenous JSRV are already encoded into sheep genome, so making a vaccine that only targets the virus would be very difficult! it might also cause autoimmune inflammatory reactions
is quarantining sheep that are suspected to have OPA a practical control solution?
noooope - incubation is 6 months - 3 years so not realistic
what virus causes ovine progressive pneumonia? (OPP)
maedi-visna virus
what kind of virus is maedi visna virus (MVV)
lentivirus (retrovirus)
if you break it down, what do maedi and visna mean?
maedi- dyspnea
visna- neurologic
true or false: most sheep infected with MVV are subclinical
true! despite the name, usually sheep do not get respiratory and especially not neuro signs
though they sometimes do!!
how is MVV transmitted?
respiratory, colostrum, sexual
what cells does MVV target?
monocytes/macrophages and dendritic cells
you are doing a necropsy on a sheep and when you open the chest you notice that the lungs fail to collapse and are covered in coalescing multifocal gray-white nodules with adjacent atelectic depressions. what is your top differential? what is the virus that causes this disease?
ovine progressive pneumonia caused by maedi visna virus
can PCR diagnose MVV?
nooooo its a ssRNA-RT so must to RT-PCR
what is the structure and replication strat of OPP/MVV
enveloped , positive sense
ssRNA-RT
what is CAE
caprine arthritis and encephalitis
what virus type causes caprine arthritis and encephalitis (CAE)
a lentivirus
what are the 4 clinical signs of CAE? what is most likely?
- polyarthritis in adults (get swelling at the carpus (with/out pain) and
thickening in and around
joints –> proliferative and
fibrinous synovitis) - encephalomyelitis in kids (sometime adults)
- indurative mastitis from lymphatic infiltration (decreased milk production)
- chronic interstitial pneumonia
usually subclinical!! (80%)
what species does CAE infect
sheep and goats
how is CAE transmitted
colostrum and milk
what cells does CAE target?
macrophages, dendritic cells, synovial membrane cells
you go to a farm and there are young goats with encephalitis, ataxia, and an inability to adduct their hind limbs. The adult goats have arthritis and weight loss, as well as poor coats. what is your top differential? how would you test for this?
caprine arthritis / encephalitis!!!
take blood and do a AGID test and ELISA
how fo you control for CAE?
prevent vertical transmission
use AGID tests to test for virus, and if there are 2 negative tests 6 months apart then youre probs safe
what is another name of orf?
contagious ecthyma , sore mouth, scabby mouth
what kind of virus is orf
poxvirus! in family poxviridae
which species are primarily infected by orf
sheep and goats!
also alpacas, muskoxen, bighorn sheep, dogs, zoonotic***
what does orf target
skin and oral mucosa
epithelial cells and keratinocytes
what is a typical histological observation with orf?
epithelial hyperplasia- ballooning degeneration of epithelial cells
is the orf vaccine super cool and awesome?
NO - there are so many adverse effects!!
including: animals developing lesions and being able to shed the virus, the vaccine can infect humans, AND it doesnt even produce long lasting immunity
what kind of virus is blue tongue? from which family
blue tongue is a orbivirus from the family Reoviridae
what species does blue tongue affect
sheep*, cattle, deer, goats, camilids
are there lots of strains of blue tongue?
yessir, up to 27 strains but there is poor cross protection stability
how is blue tongue transmitted? what does this mean regarding geography?
biting midges! from the genus Culicoides
canada is currently free, but climate change might change vector range
a farmer in Mexico calls you up to check out some sheep that he claims arent doing well. when you arrive and examine them, you note they are fibril, have ocular and nasal discharge, are drooling from ulcerated mouths, have swollen mouth, head, and necks, and are having difficulty breathing. what is your top differential?
blue tongue!!! this is an orbivirus
which serotype of blue tongue causes abortion and/or neurological signs in lambs
serotype 8 :(
what is special about cattle infected with bluetongue ?
they will be persistently infected with one strain, but will not show clinical signs until they are infected with more than one strain
the signs they get are:ulcers, lameness, hoof cracks, hair loss, and swollen tongue
which small ruminant viruses are in the family retroviridae (3)? which genus is each?
ovine maedi visna virus - lentivirus group A
caprine arthritis and encephalitis virus - lentivirus group B
jaagsiekte sheep retrovirus / ovine pulmonary adenomatosis virus - betaretrovirus
(also enzootic nasal tumor virus - betaretrovirus)
which small ruminant virus is a part of the family Reoviridae? which genus is it in?
blue tongue virus - orbivirus
(also ovine rotavirus - rotavirus)
which small ruminant viruses are in the family Poxviridae (2)? which genus is each?
orf virus -parapoxvirus
sheep and goat pox biruses - capripoxvirus
