Prions and Tumor Viruses Flashcards
What are prions?
infectious proteinaceous particles without nucleic acid
What is the incubation period associated with prions?
long
What are the neuropathological changes associated with prions?
vacuolation of neurons
Prions are abnormal ________ of normal _________
folding
glycoprotein
What is the native protein of a prion and what is its structure
PrPc
a-helical structure
What cells are prions present in?
normal cells including lymphocytes and neurons
When PrPc interacts with PrPsc what is its conformation?
B-sheet
PrPsc accumulates where? What does this accumulation lead to?
neurons
leads to vacuolation and development of neurologic signs
What are the 3 ways in which transmissible spongiform encephalopathy can arise?
Transmissible in external sources
sporadic conversion
familial mutation
What is scrapie and what species does it affect?
fatal neurologic disease of adult sheep and goats
Why is scrapie usually seen in breeding aged sheep?
due to long incubation period
What are the typical clinical signs of scrapie?
restlessness/nervousness
pruritis leading to loss of wool
emaciation
death within 6 months
What would you see histologically in a scrapie case?
no inflammation only vacuolation of neurons
True or false: Bovine spongiform encephalopathy (BSE) is not considered species specific
TRUE
What was the BSE epidemic attributed to?
feeding meat and bone meal of sheep to cattle
What led to a decline in BSE? What are the control measures in the US?
banning of ruminant-derived meat and bone meal
control measures include incarceration of small ruminant carcasses and brains and spinal cords of cattle older than 30 months
What are the clinical signs of BSE?
ataxia, hypermetria, tendency to fall
Is there horizontal transmission of BSE?
NO
What is chronic wasting disease (CWD)
TSE of elk, mule, deer, and moose
What are clinical signs of CWD?
chronic weight loss, behavioral changes, ataxia, tremors
What is the transmission of CWD thought to be caused by?
contamination of grass or in utero
What is BSE thought to have developed from?
Sheep scrapie
Which TSE variant can infect humans? Which cannot?
BSE can infect humans but sheep and deer variants cannot
Which TSE can be transmitted via infected pasture?
scrapie and CWD
What is BSE transmitted by?
ingesting brains and spinal cords
What do retroviruses contain?
reverse transcriptase
Are retroviruses labile or stable? RNA or DNA? enveloped or non-enveloped?
Labile, enveloped RNA viruses
What is the dsDNA of retroviruses integrated as in the host?
provirus
What is the insertion of a retrovirus determined by?
random - chance
Retroviruses can be endogenous or exogenous. Explain the difference
endogenous is widespread, can constitute 10% of genome, transmitted by vertical transmission, and usually silent but can recombine with exogenous retroviruses
exogenous can be horizontal transmission
What do oncogenic retroviruses induce in the cells they infect?
neoplastic transformation
What type of retrovirus is Feline Leukemia Virus
gamma retrovirus
What do most clinical FeLV infections manifest as?
anemia or immunosuppression
What are the subgroups of FeLV?
A, B, C, T
What subgroup of FeLV do all positive cats have? How would they acquire the others?
ALL HAVE A
can have others through mutation
What do cats infected with FeLV A and B have a higher risk of?
developing tumors
What does FeLV A and C result in?
fatal anemia
What is FeLV T associated with?
T-cell tropic –> immune deficiency
What cats are more at risk or more likely to be infected with FeLV?
domestic
outdoor
purebred
multi-cat household
Young cats
What are common ways of transmission of FeLV?
direct contact with saliva
fleas
iatrogenic
vertical transmission
nursing, milk
What are the virus target cells of FeLV?
mitotically active cells
FeLV infected cells are more likely to develop _______ or _________ with ________ being the most common
leukemia or lymphoma
lymphoma is most common
What is enzootic bovine leukosis?
retroviral disease of adult cattle
What is enzootic bovine leukosis characterized by?
persistent lymphocytosis and B-cell lymphoma
What is enzootic bovine leukosis transmitted by?
blood or secretions, milk, iatrogenic
What is the primary target cell of enzootic bovine leukosis?
B lyymphocyte
What is the infection time of enzootic bovine leukosis?
lifelong with most sub-clinically infected
What are common sites of enzootic bovine leukosis?
lymph nodes, heart, GIT (abomasum), liver, spleen, uterus, kidney
If you saw a lymphoma in a calve or a thymic lymphoma what would you say its relation is to BLV?
no association
Which retrovirus is associated with T cell lymphoma? B cell lymphoma?
FeLV
BLV