lecture 15- equine virology Flashcards by Abigail Brett

what strain of equine influenza still persists today? when did the other strain go away

today H3N8

H7N7 was last detected in 1977

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how many types of influenza virus are there? which is of importance with horses?

4- A, B, C, D

A is of importance with horses

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A1 is ___

H7N7

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A2 is ___

H3N8

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how is equine influenza transmitted?

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true or false: shedding of infectious influenza virus from vaccinated horses is not possible

false - it is possible

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what body system is infected by equine flu?

respiratory (ciliated epithelial cells and alveolar macrophages)

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how are mares impacted by flu virus if they are pregnant?

can cause fetal loss due to fever/clinical signs (hypoxia) but NOT directly due to the virus itself

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a group of horses presents with a fever, depression, inapp, conjunctivitis, serous discharge, dry/harsh cough

what are you concerned about

equine influenza

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what sample type is best for confirming equine flu?

nasopharyngeal swabs, blood sampes

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how does a hemagglutination inhibition test work to test for equine flu

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how is PCR used in identifying the clade equine flu ? why is this important?

identify which strain of flu

different immune response

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what is the modified live cold-adapted equine influenza vaccine? why is this significant? how is it administered?

vaccine strain is temperature sensitive and does not replicate at lower respiratory tract –> strong (and faster!) immunity at entrance of where virus would enter

can use at the face of an outbreak (unique!)

administered intranasal route

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describe how marker / DIVA vaccines work in regards to equine flu

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what is the main goal of DIVA vaccine strategy

differentiate between vaccinated and infected animals

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if there is an inefficient buffer zone with regards to emergency vaccination, what happens if an individual is introduced that is not vaccinated

pathogen can escape the vaccination buffer

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what is EVA

equine viral arteritis

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EVA is a _____ notifiable disease

annually

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the source of EVA is from…

the stallion

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stallions are _____ carriers of EVA

long term

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how is EVA transmitted

through breeding

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true or false: mares can carry EVA

false!! stallions only

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describe the pathogenesis of EVA

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a mare aborts a fetus on a breeding farm…. what virus might you be concerned about

EVA

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abortion is rare with EVA when transmitted by _____, but common with _____ transmission

rare with venereal transmission common with aerosol transmission

horse presents with depression, edema*, nasal discharge, epiphora, and urticarial rash what are you concerned about

EVA

how do viruses induce vasculitis (and thus edema)?

what is equine sarcoids caused by

bovine papilloma virus 1 and 2

how is equine sarcoids transmitted?

through fomites, but bovine must be present

true or false: equine to equine transmission of bovine papilloma virus is common

false- this is not possible

what are the gross forms of equine sarcoid?

nodular and verrucous form fibroblastic form

what is seen histologically with equine sarcoid?

epidermal proliferation - long rete pegs into dermal fibroblastic tissue

you are a veterinarian in an equine practice in north america and presented with horses for vaccination against equine influenza. the subtype you chose to vaccinate is

E- H3N8

the cold adapted equine influenza vaccines are considered safe since...

the vaccine replicates only in the upper respiratory mucosa

equine arteritis virus infection

reduces fertility in stallion

equine sarcoids

cannot be cured

what are the clinical manifestations of EHV- 1

Respiratory, abortion storm, encephalomyelitis

what are the clinical manifestations of EHV- 2

No clinical signs but associated with keratoconjunctivitis

what are the clinical manifestations of EHV- 3

Genital lesions (coital exanthema)

what are the clinical manifestations of EHV- 4

Respiratory, but rare and isolated abortions

what are the clinical manifestations of EHV- 5

Associated with equine multinodular pulmonary fibrosis

which EHV's are of the most significance?

1 and 4

how is horse herpesvirus transmitted

acquire the infection by direct or indirect contact /short distance aerosols

what is the incubation period of equine herpes virus?

1-10 days

how can herpes virus be carried?

by blood (mainly leukocytes) by lymph

where does equine herpes replicate?

respiratory tract

true or false: equine herpes does not impact repro tract, but does impact CNS

false- impacts both

what body systems are impacted by equine herpes virus 1

respiratory, repro, neuro

what equine viruses cause neurological manifestations? (6)

EHV-1 West Nile Virus Eastern Equine Encephalitis Western Equine Encephalitis Venezuelan Encephalitis Rabies

what is the typical appearance of herpesviruses on histo

intranuclear, eosinophil inclusion bodies

what samples are needed to diagnose equine herpesvirus? what tests will you run?

nasopharyngeal swab for PCR/virus isolation EDTA blood for PCR/virus isolation aborted tissue fetus for histology/immunostaining

true or false: neurovirulence is strain specific

true

how do you diagnose neurovirulent strains of equine herpes virus?

PCR (remember this!!!)

what do the attenuated and inactivated vaccines for equine herpes virus 1 protect against

attenuated- resp signs, maybe shedding inactivated- resp, abortion

how does a protected/immune horse neutralize the virus? (this is a question)

neutralizing antibodies prevent virus from binding to epithelium

what is the common name for equine infectious anemia (EIA)

swamp fever

should we be worried about EIA in alberta?

YES - it is most common here

who is susceptible to EIA? who is not?

All members of Equidae affected * Clinical disease occurs in horses and ponies * Donkeys may be without clinical signs

how is EIA transmitted?

Mechanical transmission - Mouthparts of biting insects (Horse flies, stable flies, deer flies) also: fomites in utero milk veneral aerosols

what drives the pathogenesis of EIA virus?

circulating immune complexes

what are the clinical signs of EIA?

Fever, anemia and thrombocytopenia Sudden onset acute phase (can cause death) Chronic persistent infection Recurrent clinical disease episodes Asymptomatic (silent carrier) Depression Fever Enlarged lymph nodes Weakness Weight loss Anorexia Edema Nasal discharge Mortality (50% of the diseased) condense this *

what does EIAV bind to?

erythrocytes

what does EIA do to erythrocytes? (3 things)

Decrease erythrocyte life-span Depressed erythropoiesis Impaired flow of iron from macrophage to plasma

what is significant about EIA and fevers?

causes recurrent febrile episodes - this also coinsides with thrombocytopenia

how do we diagnose EIA? (know this) what are pros and cons? can we just do one test?

serology: -agar gel immunodiffusion test, coggins test --> high false -ve) -ELISA (higher rate of false +ve) ^ we must do both of these (KNOW THIS) real time PCR (fails to detect carriers)

is EIA reportable?

yes

EIA is a retrovirus, therefore they are ____ carriers what does this mean

lifelong need to euthanize or quarantine for life

how do we control EIA

Prevent transmission between horses --> fly control, single use needles, should not breed the positive ones since virus is transmitted via in utero, via milk, venereal routes. Also prevent aerosol transmission

do we worry about west nile virus in north america?

YES

who is the vector for west nile?

mosquitos and birds

how does WNV get into brain?

axonal retrograde transport along peripheral neurons into the spinal cord or hematogenous transport across BBB

what are the clinical signs of WNV

Stumbling, in-coordination, weak limbs, partial paralysis, muscle twitching and in some cases, death, sometimes fever

vasculitis is seen with what viruses

equine herpes virus, WNV, EIA

truth or false: WNV is primarily carried by erythrocytes

FALSE - leukocytes are the issue

what viruses cause leukocyte associated viremia?

herpes, WNV

what viruses cause neurological signs?

WNV, herpes, rabies, EEE, WEE, VEE

what sample is needed to diagnose WNV?

serum

how is WNV controlled?

minimize mosquito bites

Equine herpesvirus (EHV)1 and 4 are different since

Seroprevalence of EHV1 is lower than that of EHV4

A common outcome of equine herpesvirus (EHV)1 and West Nile virus (WNV) infection is

Infection of leukocytes

What is the possible clinical sign of equine infectious anemia virus (EIAV) infection? Please mark the WRONG answer. Recurring episodes of disease Colic Fever Depression Nasal discharge

Colic

Viremia of EHV1 Follows lytic viral replication in trigeminal ganglion Occurs after infection with neuropathogenic but not with non-neuropathogenic strains Is mostly cell-associated Is not involved in viral dissemination in the body Is not evident in this infection

Is mostly cell-associated

Anemia due to equine infectious anemia (EIA) virus infection is Due to increased erythrocyte life-span Not related to compromised erythropoiesis Due to destruction of erythroblasts Non-immune mediated Due to impaired flow of iron from macrophage to plasma

Due to impaired flow of iron from macrophage to plasma

lecture 15- equine virology Flashcards

(83 cards)