RNA - Rhabdoviridae Flashcards
Morphology of Rhabdoviridae
enveloped with spikes.
bullet shaped
Helically coiled cylindrical nucleocapsid
what does the L protein do?
(1) L protein: Large protein, RNA-dependent RNA polymerase (transcriptase)
what does the G protein do?
(2) G protein: Glycoprotein that forms the envelope spikes
What does the N protein do?
(3) N protein: Nucleoprotein, associates with RNA to form the viral nucleocapsid
What does the P protein do?
(4) P protein: Phosphoprotein that mediates binding of L protein to the nucleocapsid
What does the M protein do?
(5) M protein: Matrix protein, associates with the viral nucleocapsid and lipid envelope
T/F: Rhabdoviridae had 4 genera.
False. They have 6. We only care about 4
How many genotypes are in Lyssaviruses? What’s the most important?
- 11
- Most important member of this genus: Rabies virus, genotype-1 Lyssavirus
Who injected dried, potassium hydroxide treated, infected rabbit brain material in two boys bitten by rabid dogs and both of them recovered?
Louis Pasteur
Etiology of Rabies?
Lyssavirus
Which countries are in the no risk category for Rabies?
Japan, Singapore, New Zealand, Antarctica, and many Caribbean islands
Which animals are highly susceptible to rabies?
Domestic cats and cattle
which animals are moderately susceptible to rabies?
Dogs, sheep, goat, horses, primates, and humans
How is rabies transmitted?
- Bite or scratch. its in the saliva or neurological tissues
- Aerosol has been documented
- Tranplants have been recorded in humans (liver, kidney, pancreas)
T/F: Dogs are dead end hosts for Rabies
False. it is the main reservoir
The urban cycle of rabies fominates where?
Africa, Asia, South and Central America
The sylvatic cycleis dominant where?
Europe and North America
What are the dead end hosts of Rabies?
cattle, sheep, horses, goats, and humans
What is the most important wildlife reservoir of rabies?
Bats!
In many bats, the infection is asymptomatic
Rabid bats may develop paresis or paralysis, or may be disoriented, or may sometimes show aggression
Insectivorus bats with rabies is reported where?
North America.
Vampire bats with rabies are reported where?
Mexico, Central America, and parts of South America.
In Latin America, about 250,000 to 500,000 cases of cattle rabies annually are attributed to vampire bats
Fruit bats with rabies are reported where?
Australia
Which wildlife animal account for most cases of cattle rabies?
Skunks
Which animal has been most important in the perpetuation of wildlife rabies in the central regions of USA.
Skunks
Which animal continues to be the most frequently
reported rabid wildlife species?
Raccoons
T/F: Red fox carries rabies
True
Look at notes for Pathogenesis of Rabies.
Know ALL the THINGS!
T/F: After intranasal exposure, the virus commonly enters the trigeminal nerves and ganglia in its course to the CNS.
False. This can happen but uncommon
The virus reaches the limbic system where it replicates extensively, leading to what form of rabies?
the “furious” form of rabies.
The virus spreads within the CNS continues, with replication in the neuro-cortex, resulting in what form of rabies?
the “dumb” or “paralytic” form of rabies.
T/F: the rabies virus moves centrifugally from the CNS down the peripheral nerves to a variety of organs including the adrenal cortex, pancreas and the salivary glands (via cranial nerves) in early infection.
Extenisive replication leads to high concentration in saliva
False. In late infection
T/F:
Humoral and cell-mediated immune responses normally cannot be detected during the time the rabies virus moves from site of bite to the CNS.
True
T/F: Neurons express MHC class I proteins.
False.
Neurons do not express MHC class I proteins. Also, rabies infection is non-cytopathic in muscles and nerve cells. Therefore, very little antigen is released to stimulate host defense mechanisms.
T/F: Antibodies against rabies virus appear in serum and later in cerebrospinal fluid (CSF) after neurological signs appear.
True
What does the incubation period of rabies depend on?
- dose of inoculated virus
- strain of virus
- site of bite
- degree of innervation.
Side note:
Closer site of bite to brain, shorter the incubation period.
Higher the degree of innervation at site of bite, shorter the incubation period.
What are the clinical forms of rabies?
- Prodromal
- Acute excitative (Furious form)
- MAD DOG SYNDROME and HYDROPHOBIA
- Paralytic/endstage (Dumb form
- PARALYSIS
See ppt for more details
How do you diagnose Rabies?
Direct FAT to demonstrate rabies antigen in touch impressions of brain tissue.
Negri bodies
RT-PCR
intracerebral inoculation of weanling mice - develop encephalitis within 14 days
How do rabies free countries control rabies?
Rabies free countries: Quarantine involving segregation of dogs and cats in licensed premises for 6 months.
How do endemic countries control rabies?
Endemic countries: Vaccination of dogs and cats; wildlife vaccination
Recommendation after animal has been exposed to rabies?
- Previously Unvaccinated: Euthanize immediately, or quarantine in secure enclosure for 6 months; vaccinate 1 month before release.
- Vaccinated, but not current: Evaluate case-on-case basis
- Vaccination, current: Revaccinate immediately and keep under owner’s control for 45days
What is used to control wild life rabies?
Bait vaccines
Etiology of Vesicular Stomatitis?
Vesiculovirus
The disease is caused by a group of antigenically related, but distinct viruses. No cross-protection among the different serotypes
What are the most important types of vesiculovirus?
Indiana serotype [subtypes: Fort Lupton, Alagaos, and Coccal
New Jersey serotype: The New Jersey serotype is more virulent and has the widest distribution.
Host of vesiculovirus
- Mostly cattle, pigs, and horses in the Americas. Occasionally sheep and goats
- Influenza-like disease in Humans
Where does Vesiculo Stomatitis often occur?
Americas and Caribbean
How is vesiculo stomatitis transmitted and routes of infection?
breaks in the mucosa or skin
Routes:
Contact with contaminated milking machines [teat and udder lesions]
Chewing or ingestion of contaminated fomites [mouth lesions]
Arthropods
T/F: biological transmission by arthropods is believed to be more significant than mechanical transmission
False
Disease in Cattle?
- Excess salivation and fever often are the first signs of infection in cattle and horses
- Vesicles that develop on the tongue, the oral mucosa, teats, and coronary bands of cattle rapidly rupture to leave extensive ulcers that quickly become secondarily infected.
- These lesions may cause profuse salivation and anorexia, lameness, and rejection of suckling calves.
vesicular stomatitis
What is most pronounced clinical sign of vesicular stomatitis in horses?
In horses, tongue lesions
What is most pronounced clinical sign of vesicular stomatitis in swine?
vesicular lesions are most common on the snout and coronary bands.
lameness too
T/F: In humans, vesicular stomatitis is a self-limiting influenza-like disease (headache, fever, myalgia, and weakness) lasting for 3-5 days.
True
T/F:
Vesicular stomatitis is clinically distinguishable from other vesicular diseases of cattle and pigs, including foot-and-mouth disease (cattle & pigs), Swine vesicular disease (SVD), & and vesicular exanthema of swine .
False
How do you diagnose vesicular stomatitis in horses?
Vesicular lesions in horses are characteristic only of vesicular stomatitis
T/F: Vesicular stomatitis is not reportable
False
Etiology of Bovine Ephemeral Fever (BEF)
bovine ephemerovirus
T/F: BEF has been reported in North America
false
Transmission of BEF?
Arthropod-borne
Believed to include Culicoides spp. and possibly mosquitoes
Which disease is associated wth the buffy coat fraction of blood?
Bovine Ephemeral Fever
What is left shift? And in which disease?
early neutrophilia with abnormal level of immature neutrophils in the circulation
BEF
T/F: In BEF there is an decrease in plasma fibrinogen and a significant increase in plasma calcium.
False. There is an increase in plasma fibrinogen and a significant decrease in plasma calcium.
Disease in Cattle?
Fever, which is often biphasic, triphasic or polyphasic.
Inappetence, excessive salivation, serous nasal discharge, drooling, increased heart rate, dyspnea, stiffness and lameness, and a sudden decrease in milk yield.
Bovine Ephemeral Fever
How long does it take to recover from BEF?
- Recovery is dramatic and usually complete in 3 days [2-5 days]
- Some animals may become recumbent and paralyzed for 8 hr to >1 wk.
how do you diagnose BEF?
inoculation of infected buffy coat cells into cell cultures derived from Aedes albopictus, or IC inoculation of sucking mice.
