Flaviviridae Flashcards
Who were the first doctors to recognize Yellow Fever (a flavivirus) as a filterable agent?
Walter Reed and James Carroll
What are the 3 genera of Flaviviridae
Flavivirus
Pestivirus
Hepacivirus
What glycoproteins can be found on the envelope of flaviriuses?
E1 or E2
Flaviviruses are ________ stranded, _______ sense RNA
Single stranded
positive sense
T/F: Flavivirus RNA is infectious
TRUE
Where in the cell does replication occur?
Cytoplasm
Where are viral proteins transported to after synthesis?
Endoplasmic reticulum
This differs from other viruses that immediately send viral proteins out of the cell
T/F: Release of flaviviruses from host cells causes cell lysis
FALSE (differs from other viruses)
this is why many times these viruses may be asymptomatic
T/F: Heat, disinfectants, and lipid solvents inactivate flavivirueses
TRUE
***classical swine fever virus is the only exception - may withstand the heat of cooking
Who are dead end hosts of West Nile Virus?
Horses and humans
In who is the West Nile Virus maintained?
Mosquitoes and Birds
T/F: Horses have high viremia when infected with WNV
FALSE
this is why they are a dead end host
What are clinical signs in birds with WNV?
High viremia, widespread necrosis and hemorrhage of organs –> DEATH
What is the prognosis for a horse with WNV showing neurological signs (ataxia, recumbence)?
POOR
What clinical signs may you see in a horse with WNV?
HIGH FEVER, decreased appetite, depression, weakness, neuro signs
When should samples be collected for dx testing of WNV in a horse and what sample will you collect?
Blood collection should happen within 5 days of clinical presentation of west nile virus
What is the preferred dx test for WNV?
ELISA - looking for IgM
other - virus neutralization, RT-PCR, immunohistochemistry, virus isolation
T/F: Horses who recover from WNV will have good immunity and not require the vaccine in the future
TRUE
What genus does BVDV (Bovine viral diarrhea virus) belong to?
Pestivirus
T/F: BVDV can infection sheep, goats, and swine
True
Cattle are the most important host affected by this virus
What makes an outbreak of BVDV in a naïve herd different than a herd that has had previous exposure?
Higher morbidity and mortality in naïve herds
Easier to dx in naïve herds
What are the MOT of BVDV?
Vertical -> embryo/fetus
Food contamination and artificial insemination
(virus is shed in nearly all secretions and excretions)
What clinical signs do you see in a non-pregnant cow with BVDV?
*most common in young cows
Decreased milk production, biphasic fever, DHR,
**Nasal discharge and ulcerations on lips, muzzle, oral cavity
What clinical signs do you see in a pregnant cow with BVDV?
Early pregnancy: embryonic death and resorption
Before immunological competence of fetus: “weak calf syndrome”, Birth deformities and retarded growth post birth, calves that survive will be SERONEGATIVE carriers
Late: may have immune response and eliminate virus
What is the mechanism that occurs to a calf in utero that allows it to be born as a seronegative carrier of BVDV?
immunotolerance
What is the mortality rate in calves with persistent BVDV infection?
50%
What are 2 disease syndromes of BVDV?
Bovine viral diarrhea Mucosal disease (comes after BVD - chronic)
What are 2 BVDV types?
Cytopathic and non-cytopathic (usually persistent)
What clinical signs will you notice in a cow with chronic mucosal disease due to BVDV?
*Skin ulcers and hyperkeratosis on head/neck/shoulders
will note necrosis at the crypts of enterocytes at necropsy
What dx test(s) should be performed to dx BVDV?
Virus isolation
Immunohistochemistry with ear notch sample
Then confirm with RT-PCR
What must be done before vaccinating a herd of cattle for BVDV?
Must perform screening and eliminate any carriers
Inactivated/attenuated and modified live vax available
T/F: Classical swine fever is a reportable disease
TRUE!!!!
T/F: Classical swine fever outbreaks occur periodically in the US
FALSE
Classical swine fever has been eradicated in:
North America, Australia, NZ, Ireland, UK
What is the MOT of classical swine fever?
Oronasal route - direct contact/fomites
May be present in contaminated pork products
What dz type is most common form of classical swine fever and what clinical signs will you see? (ex: peracture, acute, chronic)
ACUTE (mortality can reach 100%)
high fever, **hyperemia from ear tips –> progresses all over body (redness), anorexia, depression, DHR/vomiting, conjunctivitis, CNS signs
What samples and tests should be collected/performed to dx classical swine fever?
Tissue samples should be collected and sent to a REFERENCE LAB for ELISA or RT-PCR
How do you treat classical swine fever?
CULL
T/F: There is no vaccine available for classical swine fever
FALSE
attenuated and live vaccines are available
T/F: ticks can transmit west nile virus
TRUE
