equine viral diseases 1 - Steph Flashcards
equine influenza virus family
orthomyxoviridae
equine influenza viral structure
ssRNA virus, 8 segments, 11 proteins
name the influenza virus types
A,B,C,D
which influenza virus type infects equine
Influenza virus A (H3,H7)
equine influenza A1 is also known as
H7N7
equine influenza A2 is also known as
H3N8
what is the relationship between equine and canine influenza
equine influenza virus mutated to produce canine influenza virus
- H3N8 influenza virus closely related , flu virus jumped from horses to dogs (changed tropism)
which equine influenza suntype is common and crosses to canines?
equine influenza A2 - H3N8
hosts of equne influenza
horses, donkeys, mules, dogs
how is equine influenza transmitted
highly contagious aerosols (coughing etc.)
when is equine influenza virus excreted
excreted during the incubation period and for at least five days after the onset of clinical signs
who is able to shed equine influenza virus
vaccinated and infected horses are able to shed
incubation period of equine influenza virus
1-3 days
which cells does equine influenza target
ciliated epithelial cells and alveolar macrophages
where does equine influenza virus replicate
upper and lower respiratory tract epithelium
what are the consequences of equine influenza replication in the upper and lower respiratory tract epithelium
destruction of ciliated epithelium and secondary bacterial infection –> laryngitis, bronchitis and bronchointerstitial pneumonia –> pulmonary congestion and edema
what happens when there are equine influenza virus outbreaks among heavily pregnant mares
increased neonatal losses because of premature placental separation and dystocia causing fetal hypoxia –> may be related to high fever and not due to fetal infection
what causes equine pneumonia
equine influenza plus a secondary bacterial infection
how long until a horse can resume athletic activity after being infected with equine pneumonia
50-100 days
clinical manifestations of equine influenza
- high fever (39-41)
- depression (4-5 days)
- inappetence
- reddening of nasal mucosa
- conjunctivitis
- serous later mucopurulent discharge
- fatal in foals <2 weeks old
- characteristic harsh, dry paroxysmal cough
T/F: secondary bacterial infections are uncommon with equine influenza
FALSE!!! secondary bacterial infections are COMMON with equineinfluenza
in the absence of complications, how long does it take for a horse to recover from equine influenza
2-3 weeks after infection
morbidity and mortality of equine influenza
morbidity: 90%
mortality: low, 20%
diagnosis of equine influenza
Clinical signs: rapidly spreading respiratory infection, rapid onset, high fever, depression, cough
nasopharyngeal swabs
blood samples
why is it necessary to define the strain when diagnosing equine influenza
due to the wide range of stains and the use of vaccines
how long is equine influenza excreted for
7-10 days
how can you isolate/inoculate equine influenza virus in an embryo
inject virus isolation into allantoic and amniotic cavity, incubate for 3-4 days and collect the fluid
what is a hemagglutination inhibition test? what is it used for?
detects antibodies specific for influenza. control cell wells will show complete settling (button) while there will be an inhibition of agglutination by test virus (i think…)
from google: the hemagglutination inhibition (HI) assay is used to titrate the antibody response to a viral infection. The HI assay takes advantage of some viruses’ ability to hemagglutinate (bind) red blood cells, therefore forming a “lattice” and preventing the red blood cells from clumping.
what is the purpose of using RT-PCR when dealing with equine influenza
seperates sub lineages that are available, sequences them to help identify them into clades
what vaccines are available for equine influenza
killed, live modified, recombinant vaccines
describe the killed vaccine for equine influenza (strain used, how many vaccinations required)
H3N8, multiple vaccines necessary
describe the routes of administration, number of vaccines required for modified live vaccine for equine influenza
intranasal, protects up to 12 months - needs annual vaccination
describe the recombinant vaccine for equine influenza
canary pox vector based, 2 doses needed initially and then revax annually
at what age may maternal antibodies interfere with efficacy of vaccine against equine influenza in foals
vaccination before 6 weeks partuition may interfere
at what age are maternal antibodies provided to the foal against equine influenza
2-6 weeks
which vaccine for equine influenza can be administered during an outbreak and why?
modified live cold adapted. when given intranasal, close to environmental temperature vs in lower respiratory tract it is closer to 38-39 degrees and will not replicate. (remember that vaccinated individuals still shed the virus)
which vaccine against equine influenza is a DIVA/marker vaccine ?
recombinant canary pox vector vaccine
horses that have the DIVA vaccine for EIV: test / have immunity for (+/-) for hemagglutinate and test (+/-) for nuclear capsid proteins
serological testing:
test positive for hemagglutinate
test negative for nuclear capsid protein
horses that have been infected by WT EIV: test for (+/-) for hemagglutinate and test (+/-) for nuclear capsid proteins
serological testing:
test positive for hemagglutinate
test positive for nuclear capsid protein
horses that have the vaccine without DIVA for EIV: test / have immunity for (+/-) for hemagglutinate and test (+/-) for nuclear capsid proteins
serological testing:
test positive for hemagglutinate
test positive for nuclear capsid protein
what are the implications for the modified live vaccine against equine influenza to be cold-adapted
virus replicates in the upper respiratory tract but not the lower mucosa –> immunity –> neutralize the virus at entry point
what is a vaccination buffer zone
vaccination of all susceptible animals with the hope to significantly decrease virus shedding to protect populations outside the buffer zone
2 outcomes of emergency vaccinations
efficient buffer zone where horse outside of vaccination buffer zone is protected
inefficient buffer zone where virus shedding is sustained and pathogen escapes the vaccination buffer
control measures for equine influenza virus
- 2 week isolation when new animals arrive + vaccination
- isolate suspected infected horse at least 50m apart
- amantadine and rimantadine (associated with CNS adverse effects and poor oral availability)
- rest in non-stressful environments
equine viral arteritis order and family
order: nidovirales
family: arteriviridae
hosts of equine viral arteritis
equidae, south american camelids
T/F: equine viral arteritis is a annually notifiable disease
true
what type of genome does equine viral arteritis have ?
ssRNA positive sense
EAV geographical distribution
recorded in most countries except iceland and japan
transmission of EAV l
lateral spread via. personel, teaser, fomites, or during semen collection
Sexual transmission:
venereal transmission
contaminated frozen semen
what is the natural reservoirs for EAV***
carrier stallions (no carrier state in mares, geldings and foals)
replication of EAV occurs in what type of cells
alveolar macrophages
pulmonary blood vessel endothelial cells
type II pneumocytes
what days are neutralizing antibodies present for EAV
day 6-40
what days is the EAV present in blood
only day 3-5
what is the time period for EAV to be shed in the semen
day 7-40
2 possible pathogeneses of EAV abortion
- leukocyte associated viremia: EAV infects uterine blood vessels and myometrium –> vasculitis and myometritis with ischemia followed by precocious chorionic detachment –> uninfected aborted fetus
- leukocyte associated viremia: EAV infects uterine blood vessels and myometrium –>EAV infects areolar trophoblast chorionic mesenchyma and sporadically the fetus –> infected aborted fetus or infected newborn foal
clinical signs of EAV infection
- depression
- limb edema
- nasal discharge
- periorbital edema/conjunctivitis
- epiphora
- scrotal/preputial edema
- edema, mammary glands
- utricarial rash
incubation period of EAV
1-14 days
clinical features of EAV
high fever, depression, anorexia, leukopenia
clinical features of foals infected with EAV
sporadic death due to interstitial pneumonia
clinical features of stallions infected with EAV
- decreased fertility –> reduced sperm quality because of increased scrotal temperature and edema
- decreased libido
main lesion found in horses infected with EAV***
vasculitis: perivascular edema, necrosis of arterial wall, lymphocytic infiltration
postmortem lesions found in acute cases of EAV
- edema, congestion, hemorrhages
- fluid accumulation in body cavities
postmortem lesions found in foals infected with EAV
- pulmonary edema, interstitial pneumonia, splenic infarcts, enteritis
postmortem lesions found in aborting mares with EAv infecction
- endometrial hemorrhages
- partially autolyzed fetuses
5 ways to diagnose EAV in lab
Virus isolation: semen, rabbit kidney cells
nucleic acid detection: RT-PCR
antigen detection: immunohistochemistry
serology: virus neutralization, ELISA
carrier stallions can be detected by breeding to two seronegative bares
vereneal transmission prevention and control of EAV
- separate pregnant mares from other horses
- isolate new arrivals
breed carrier stalions only to well vaccinated or seropositive mares
carrier stallion prevention and control of EAV
- physically isolate from uninfected horses
- clean and disinfect fomites
vaccines available against EAV
- modified live virus vaccine (only in NA)
- inactivated vaccine (only europe)
vaccination protocol against EAV
vaccinate before breeding season to protect uninfected stallions
describe the structure and genome of bovine papilloma virus
non enveloped (resistant)
double stranded circular DNA genome
where does bovine papilloma virus replicate
germinal layer of skin in bovines (NOT EQUINES)
What is the most commonly diagnosed tumor of equids
equine sarcoids
what is equine sarcoids caused by
bovine papilloma virus 1 and 2 (non enveloped)
why is bovine papilloma virus not transmitted from equine to equine***
bovine papilloma virus does not complete replication cycle within equine epithelial cells –> no amplificatiton fo the virus within equid species –> so no transmission between equid species
transmission of bovine papilloma virus
fomites (bovine species must be present)
where is the nodular and verrucous form of equine sarcoid commonly found
groin, sheath, face
where is the fibroplastic form of equine sarcoid found
predilection for legs, groin, eyelids and sites of previous injury
clinical presentations of equine sarcoids
- multiple extensive verrucose
- multifocal fibroblastic sarcoid
- eyelid sarcoids
- fibroblastic sarcoid on the pastern region
describe the histological findings of an equid infected with bovine papilloma virus
- epidermal proliferation –> long rete pegs into the dermal fibroblastic tissue which contains immature fibroblasts with mitotic figures in a whorled fibrocellular mass
treatment of equine sarcoids
currently no effective treatment, efficacy is difficult to quantify
