RNA Viruses 2: Orthmyxoviridae, Coronaviridaes Flashcards
What is Orthomyxoviridae?
influenza
Orthomyxoviridae virus type?
SSRNA, NEGSense, Enveloped, Helical
Special characteristics of Orthomyxoviridae genome
SSRNA NEGSense- Segmented
Can perform Reassortment.
What is Reassortment?
Only occurs in RNA viruses with segmented genomes- Random mixing of the various segments when a cell is infected multiple viruses
What is the outcome of reasortment
-Rapid antigenic shifts in the influenza virus
- Point mutation result in new strains
Orthomyxoviridae has what type of VAP?
Spike proteins
What is Orthomyxoviridae?
influenza
What is hemagglutinin?
Spike protein on influenza virus- Responsible for virus attachment and envelope fusion
What is neuraminidase?
Spike protein on influenza virus capable of cleaving viral receptors, degrading mucus and promoting both entry and release of virions from host cells.
What is the reservoir of orthomyxoviridae?
aquatic birds
What are the hosts of orthomyxoviridae?
Birds, marine mammals, swine, horses, human, dogs
What species is the influenza reassortment host? Why?
Swine
Bc human and avian viruses replicate well in swine
What does orthomyxoviridae replicate in birds?
Gastrointestinal tract
How does orthomyxoviridae transmit from birds?
LPAI transmission by fecal-oral
How does human contact of AI occur?
Close contact and poor hygiene
When did HPAI appears in the US?
2014
What happened with avian influenza in 2020?
LPAI appeared in NC and spread to SC then mutated to HPAI
How to get rid of HPAI?
Culling
Risk factors of spread of HPAI
- Contact between wild and domestic birds
- live bird markets
- close contact between humans and infected poultry
Equine influenza is what type of virus?
Type A influenza
- orthomyxoviridae
Equine influenza susceptible population?
1-5 yr old horses
Equine influenza outbreaks are associated with what?
- Shows
- Sales
- Racing
- Training
Equine influenza clinical signs
Cough
high fever (106)
Nasal discharge
Equine influenza transmission?
aerosol or fomites
Equine influenza replication site?
epithelial cells in Upper respiratory tracts
Leading to rhinitis and tracheitis
Swine influenza is what type of flu and what virus?
Type A and C
Orthomyxoviridae
Swine influenza clincial signs
cough
high fever
nasal discharge
Sometimes abortion
In what species does flu lead to abortion?
Swine
Swine influenza transmission?
Direct contact
areosol
Swine influenza replication site?
epithelial cells in Upper respiratory tracts
Leading to rhinitis and tracheitis
What is canine influenza thought to come from?
H3N8 (equine lineage)
H3N2 (avian lineage)
both nutated to allow dog-dog spread
What is the infectious/incubation period of canine influenza?
2-4 days before onset of clinical signs
canine influenza replication sites?
Epithelium of upper respiratory tract including nasal mucosa and bronchioles
leads to rhinitis, tracheitis, bronchitis, and bronchiolitis
canine influenza clinical signs
cough
high fever
and nasal discharge
What is copy-choice recombination?
Occurs btwn +SSRNA viruses
- RNA polymerase switches between template strands during synthesis of the complimentary negative strand
- Leads to exceptionally high frequency of genetic recombination
Types of coronaviridae?
Alphacoronavirus 1
Porcine epidemic diarrhea virus (PEDV)
Betacoronavirus 1
Types of alphacoronavirus 1?
Feline coronavirus
– Feline infectious peritonitis virus
Transmissible gastroenteritis virus (TGE)
Canine coronavirus
Types of betacoronavirus 1
Bovine coronavirus
Equine coronavirus
Canine respiratory coronavirus
What leads to feline infectious peritonitis virus?
- Feline enteric coronavirus shed from carrier cat and replicating in kittens
- Recombination or mutation of spike
-Productive infection in MONOCYTES AND MACROPHAGES
Where does feline infectious peritonitis replicate?
Macrophages and monocytes
What does feline infectious peritonitis lead to? (3 outcomes)
- Inadequate cell-mediated immunity
- ineffective cell-mediate immunity
- Effective cell-mediated immunity
What does inadequate cell mediated immunity of feline infectious peritonitis lead to?
- B-cell activation of non-productive antibodies
- Intermittent replication of feline infectious peritonitis (periodic shedding)
- Immune-mediated vasculitis (Perivascular clusters of virus infected macrophages)
What is immune-mediates vasculitis of feline infectious peritonitis?
Perivascular clusters of virus infected macrophages
What does immune-mediated vasculitis of feline infectious peritonitis lead to?
Either
- Severe
- Moderate
infection of feline infectious peritonitis
What does ineffective cell-mediates immunity of feline infectious peritonitis cause?
- B-call activation of non-productive antibodies
- CONTINUOUS replication of FIPV
- Immune-mediated vasculitis (perivascular clusters of virus infected macrophages)
What are the outcomes of severe feline infectious peritonitis?
- marked vascular permeability
- Effusive “wet” FIPV
- Progressive fatal disease in WEEKS
What are the outcomes of moderate feline infectious peritonitis?
-Pyogranulomatous lesions of intestines and kidneys
- Non-effusive “Dry” FIPV
- Progressive fatal disease in MONTHS
What is the most appropriate ante-mortem test for FIPV?
Immunohistochemistry of biopsies of affected organs
Is there a safe and effective vaccine for FIPV?
NO
Does canine corona virus consistently cause disease?
No- very variable
What are the types of canine coronavirus?
CCoV type 1
CCoV type 2
What betacoronviridae is a genetically distinct version of the alphacoronaviridae- canine corona virus?
Canine respiratory coronavirus
-Mild respiratory disease particularly in kenneled dogs
What is transmissible gastroenteritis (TGE)?
Highly contagious corona virus in young pigs
Alphacoronaviridae
Where does transmissible gastroenteritis (TGE) occur?
Worldwide
What is porcine respiratory coronavirus?
A relatively non-pathogenic respiratory variant of transmissible gastroenteritis (TGE)
What does transmissible gastroenteritis (TGE) do?
Severely disrupts the digestion and cellular transport of nutrients
What is the outcome of transmissible gastroenteritis (TGE)?
Fluid accumulation in the intestinal limen and SEVERE diarrhea
transmissible gastroenteritis (TGE) in piglets?
Sudden onset and rapid spread.
- Almost 100% mortality
What is bovine coronavirus?
Betacoronaviridae
What does bovine coronavirus cause?
- Calf diarrhea
- Winter dysentery in adult house cattle
What is winter dystenery?
highly contagious GI disorder that affects housed adult dairy cattle, primarily during winter. Clinical features include profuse diarrhea (sometimes accompanied by blood and mucus), a profound drop in milk production, variable anorexia and depression, and mild respiratory signs such as coughing.
What is the average age of onset of bovine coronavirus in calves?
7-10 days
How is bovine coronavirus transmitted?
Fecal-oral
What does bovine coronavirus do to the small intestine?
Causes blunting, fusion, and necrosis of villi in SI
What is equine coronavirus?
Betacoronavirus
equine coronavirus clinical signs?
Usually subclinical
- Enteric disease in foals
What leads to onsets of bovine and equine coronavirus?
- Winter months (housed inside)
- Stressed animals
- Poor environmental conditions
In general where does coronavirus replicate?
Respiratory epithelium
in general what is the severity of corona virus in adults?
Mild
in general what is the severity of corona virus in young?
Severe
In what species does coronavirus cause the worst diarrhea?
piglets and calves
What does feline enteric coronavirus mutate into?
feline infectious peritonitis
