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Virology > Exam 2- Herpesviruses > Flashcards

Exam 2- Herpesviruses Flashcards

1
Q

List the multisystemic α herpesviruses of veterinary importance

A

EHV-1

EHV-4

Bovine herpesvirus 1 and 5

Marek’s Disease virus

Pseudorabies virus

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2
Q

What form of equine herpesviruses is most commonly associated with respiratory infections?

A

EHV-4 is mainly associated with respiratory infections. This strain has tropism for respiratory epithelial cells, and neuronal cells.

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3
Q

What is the major difference in EHV-1 and EHV-4

A

They differ in tropism. EHV-1 readily infects a broader range of cells which will impact pathogenesis

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4
Q

A 3yo. Horse recently traveled and you do a PE. The horse has rhinopnemonitis, that was acute. There is a fever present with mild/moderate nasal discharge. There is NOT a cough present. What is your plan of action?

A

You suspect the horse has a respiratory virus. You decide you need to run diagnostics to differentiate the virus from equine influenza. Rhinovirus, or the respiratory form of equine viral arteritis. You choose to send in nasal swabs for viral isolation. Check with your lab on what exact samples they would prefer

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5
Q

What is a complication that can occur with EHV-4 infection especially in younger horses?

A

secondary bacterial infection

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6
Q

What form of equine herpesvirus is most commonly associated with reproductive disease?

A

EHV-1 is most commonly found, but occasionally EHV-4. This can be seen with, or without respiratory disease, myeloencephalitis. Abortions generally occur during the last 4 months of gestatoin, but can occur earlier. A foal that is born live, with die shortly after. Abortino storms are common and are prevented by good management practices.

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7
Q

What are herpesvirus characteristics that allow it to cause aboritons in horses?

A

The virus has the ability to replicate in endothelial cells and lymphocytes. They also have the ability to invade allantochorion resulting in placental and fetal ischemia.

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8
Q

What is EHM

A

This is Equine Herpes Myeloencephalitis. This is the neurological form of an equine herpes virus infection. This is most commonly associated with the EHV-1 form of the virus.

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9
Q

What are clinical signs of EHM?

A

Weakness, and paralysis of the muscles of the hind limbs, giving raise to incordination, gait abnormalities, and may end up in the animal in a sitting position.

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10
Q

How was the hypervirulent strain of EHV-1 created?

A

There was a mutation in the viral polymerase gene which results in a 10 fold increase in virus replication in EHV-1 ORF 30.

This strain has high morbidity and case fatality rates associated with it, and is resistant to vaccination.

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11
Q

How does systemic spread of EHV-1 occur?

A

Virus causes a lytic infection of epithelial cells in the upper respiratory tract. The virus spreads to cells underlying the lamina propria- endothelial cells, lymphocytes, macrophages. Replication in regional lymph nodes (mild lymphadenopathy). Cell-associated viremia. There is a non-productive infection in lymphocytes. Virus dissemiated to uterine and CNS vascular endothelium. Disseminated to neurons of trigeminal nerve with persistent latent infection of trigeminal ganglion.

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12
Q

Is infection of the endothelial cells necessary for abortion and neurologic disease?

A

yes. This is required

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13
Q

What form of equine herpesvirus is associated with lymphotropism during latent infections?

A

EHV-1 is more lymphotropic can can establish latency in T-lymphocytes.

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14
Q

what age of a horse is often associated with an initial herpesvirus infection?

A

3-5 months of age. This often coincides with declining maternal antibody

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15
Q

What are other differentials for the respiratory form of Equine herpesviruses?

A

influenza, respiratory form of equine viral arteritis, rhinovirus.

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16
Q

What are other differentials for the neurologic form of equine herpesviruses?

A

Wobblers (cervical stenotic myelopathy)- CSM

Equine degenerative myelitis - EDM,

Equine protozoal myeloencephalopathy- EPM

trauma, arboviral encephalidites

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17
Q

What are other differentials for the reproductive form of equine herpesviruses?

A

Equine viral arteritis virus.

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18
Q

What are mechanisms of diagnosis for EHV?

A
  • Viral isolation through the collection of samples from cell cultures.
    • Lung, liver samples of aborted fetus
  • Immunohistochemistry
  • Serology- neutralizing test is most common
  • PCR
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19
Q

What are control practices for EHV?

A

Minimize stress, segregate horses with clinical signs and those recently stressed. Get foals immunized before exposing to outside horses if possible.

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20
Q

Are vaccinations effective for EHV?

A

Vx effectiveness is a problem with this, as with most herpesviral diseases. There is incomplete protection regardless of the vaccine type, or administration route. The protection is short-lived. Maternal immune components will interfere with vaccination in young animals. EHV-1 and EHV-4 are cross-protective, and vaccine failures appear NOT to be due to a lack of shared antigens between the two strains.

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21
Q

What herpesvirus type is commonly associated with respiratory infections in cattle?

A

BHV-1 is associated with respiratory and reproductive bovine diseases.

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22
Q

What clinical syndrome is associated with BHV-5

A

This is the causative agent of neurological disease.

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23
Q

What are the natures of diseases for Bovine Herpesviruses?

A
  • Respiratory disease- most important economically
    • URI- fever, depression, anorexia, mucopurulent nasal discharge followed by ulceration and necrosis of muzzle
    • Secondary bacterial pneumonias may be common in feedlot situations. IBR is an important component of shipping fever
    • Broad range of severity
  • Abortion- may be seen alone or with respiratory disease. Important economically
  • Vulvovaginitis and balanoposthitis
  • Perinatal mortality
  • Keratoconjunctivitis
  • Encephalitis (BHV-5)
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24
Q

What is the pathogenesis of BHV?

A
  • Initial entry via nasopharyngeal membranes
  • Localized viral replication may or may not lead to clinically-apparent respiratory disease
  • compromise of upper respiratory defense mechansims may lead to bacterial pneumonia
  • Viral replication in regional lymphoid tissues
  • Viremia
    • In viremic newborn calves, inflammatory disease and necrosis in lung, liver, and intestine.
    • If viremia crosses from mother to fetus Abortion
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25
Q

Where in the body is BHV latency associated?

A

sensory ganglia of nasopharynx, also potentially in the lymphocytes and monocytes.

Periodic Reactivation and Shedding can occur

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26
Q

What are differential diagnoses for an animal with BHV?

A

Bovine Respiratory Syncytial virus (BRSV)

Parainfluenza-3 virus

Bovine viral diarrhea virus (BVD)

Malignant catarrhal fever (MCF)

27
Q

How would you diagnose BHV?

A

viral isolation from pharyngeal swabs taken early in clinical disease

Immunohistochemistry-detects viral antigen in tissues

Serology- serum neutralization tests

28
Q

What are methods of control for BHV?

A

Minimize stress, segregate animals with clinical signs and those recently stressed

Vaccination- offer some protection for either abortion or respiratory disease. They do not prevent infections but will ameliorate clinical disease. As with most herpes vaccines. Protection is short lived.

29
Q

For both EHV and BHV, what is the reservoir for virus?

A

Animals that have reactivated a latent infection

30
Q

During Viremia, when do you want to collect samples?

A

Early in the infection.

31
Q

What is Gallid Herpesvirus-2?

A

Marek’s Disease Virus

32
Q

What disease is a common neuropathic, neoplastic, economically important, lymphoproliferative disease in the poultry industry?

A

Marek’s disease virus.

33
Q

What are the 4 different pathotypes of Marek’s Disease virus?

A

Mildly virulent

Virulent

Very Virulent

Very Virulent Plus

34
Q

What is the nature of Marek’s Disease Virus?

A
  • Progressive disease with variable clinical sings
  • Neurolymphomatosis
    • Enlargement of peripheral nerves
    • Asymmetric paralysis
  • Acute Marek’s Disease
    • Explosive outbreaks affect large proportions of birds in flock
    • Depression, ataxia, significant mortality
  • Ocular lymphomatosis
  • Cutaneous Marek’s Disease
35
Q

List the 4 phases of infection

A
  1. Early productive-restrictive virus infection causing primarily degenerative changes
  2. Latent infection
  3. A second phase of cytolytic productive-restrictive infection coincident with permanent immunosuppression
  4. A Proliferative phase involving nonproductively infected lymphocytes.
36
Q

How long does Marek’s disease live in the dust and dander?

A

It can live there for months. Readily transmitted in dust and dander form infected chickens. Infections quickly spread regardless of vaccine status.

37
Q

What are methods for diagnosis of Marek’s Disease virus in chickens?

A

diagnosis based on enlarged nerves (especially sciatic) and lymphoid tumors in various viscera

Can be confirmed histologically, PCR

38
Q

What are methods of controlling Marek’s Disease Virus?

A

Vaccination- effectiveness of vaccines periodically compromised by emergence of vaccine resistant strains

Breeding genetic resistance into flocks

39
Q

What is the common name for Suid Herpesvirus 1?

A

Pseudorabies virus

40
Q

What species can pseudorabies virus be transmitted to?

A

cattle, dogs, cats, sheep, goats, racoons, skunks, rodents

These are dead end hosts, and the condition tends to be fatal.

Reportable disease

41
Q

What are methods for transmission of Suid Herpesvirus 1?

A

Direct contact- nose to nose

Venereal- Semen

Transplacental

virus survives up to 7 hr with relative humidity >55%

Aerosol spread under the right conditions

42
Q

What are the main methods for control of Suid Herpesvirus 1?

A
  • Biosecurity
  • Vaccination
    • MLV, gene deletion Vx, reduce shedding, protect against neurologic disease. Safe for pigs of all ages
  • Eradication program
    • All states were declared PRV-free in 2006
43
Q

CHV-1

A

Hemorrhagic Disease of Pups

  • CHV-1 is temperature sensitive
  • Rare highly fatal, generalized hemorrhagic disease of pups - hypothermia under 3-4 weeks of age.
  • Genital disease in mature animals but is rarely diagnosed clinically.
44
Q

Neonatal puppies infected with CHV-1

A
  • Acute infection that is rapid and the course of disease is fatal
  • Signs include painful and persistent crying, abdominal pain, depression and anorexia
  • No fever- rectal temp become subnormal before death
45
Q

Older dogs infected with CHV-1

A

May be focal nodular lesions on the vaginal, penile and prepucial epithelium

46
Q

What is the pathogenesis of CHV-1

A

Infection of oronasal epithelium

hypothermia can lead to generalized, often fatal disease

Cell-associated viremia in macrophage

Dissemiation throughout body

viral replication in blood vessel walls- vasculitis hemorrhage, thrombocytopenia.

47
Q

When evaluating a foal fetal liver infected with EHV-1, what is the most diagnostic finding?

A

inclusion bodies in the hepatocytes.

48
Q

where are latent infections isolated from for horses with EHV?

A

T cell lymphocytes.

49
Q

What gross lesions are seen with CHV-1

A

Large ecchymotic hemorrhages of parenchymal organs.

50
Q

What methods of control can be utilized for CHV-1

A

Vaccinations are not available

Elevation of body temperature early in infection may have a theraputic effect

51
Q

what is the major Gammaherpesvirus we need to be aware of in veterinary Medicine?

A

Malignant Catarrhal Fever

52
Q

What viruses make up MCF

A
  • Alcelaphine herpesvirus type 1
    • Occurs in Africa mainly
  • Ovine herpesvirus 2
    • Sheep associated MCF virus.
53
Q

What species are susceptible to MCF

A

cattle, bison, some species of deer, certain other exotic and domestic ruminants. Bison and deer are somewhat more susceptible than cattle: develop more severe and rapid disease

54
Q

What species of animals are carrier species of MCF

A

wildebeests and sheep- do not show clinical signs

55
Q

Explain what type of disease MCF is

A
  • Pansystemic disease of lymphoid and epithelial cells; primary clinical signs referable to upper respiratory and intestinal tracts, eyes, skin, lymph nodes
    • severe erosions and ulcers of affected systems; especially rhinitis, keratoconjunctivitis, panopthalmitis, stomatiits, gastroenteritis, encephalitis
    • Corneal opacity is a characteristic clinical disease that is usually present.
56
Q

You go out to Farmer John’s herd of cattle and several present:

What questions do you want to ask Farmer John?

A

Are there any sheep in the area?

You suspect MCF

57
Q

What age of sheep are associated with the greatest transmission of MCF

A

shep 6-8 months of age.

wildebeest calves shed as neonates, and virtually cease by 4 months of age.

58
Q

How are lambs infected with MCF?

A

infected from other sheep horizontally, during the first few weeks of life.

59
Q

You confirm a case of MCF, but what are other Ddx were on your list?

A

BVD

Severe IBR

Rinderpest, foot and mouth disease, and vesicular stomatitis

60
Q

How is MCF diagnosed?

A

characteristic clinical signs, history of exposure to sheep or wildebeests, histologic lesions in blood vessels and elsewhere, and laboratory tests for the virus.

The PCR test detects viral DNA in lymphocytes of infected animals- this is the best test for diagnosing acute disease

61
Q

How do you control MCF

A

Physically separate susceptible species from sheep or wildebeests.

It is possible to produce virus-free sheep by removing them from the flock prior to infection. They then pose no threat to susceptible species.

62
Q

Is there a vaccine for MCF?

A

no

63
Q

blank

A

blank wouldn’t delete

Virology (6 decks)

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