Viruses and GI disease Flashcards

1
Q

Describe the features of parvoviruses

A

Icosahedral capsid
No envelope
Small, linear ssDNA genome
Infect and kill actively replicating cells
Persist for long periods in environment

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2
Q

Which parvoviruses are of veterinary importance?

A
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3
Q

Describe the effect of parvovirus in the villi of the SI

A

Grow in dividing stem cells in the crypts
Villi tip cells turnover normally but are not replaces as virus kills stem cells
=> stunted villi, malabsorption, maldigestion

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4
Q

Describe Feline infectious enteritis/feline panleukopenia

A

Faecal-oral transmission
Persists in environment up to a year
Infects lymph nodes of naso and oropharynx => spreads to other tissues
Mainly infects intestinal cells and bone marrow
Kittens most susceptible

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5
Q

Describe the pathogenesis of feline panleukopenia via parvoviruses

A

Decreased WBC count, killing of lymphoid and myeloid stem cells
High risk of secondary bacterial infection

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6
Q

Describe the pathogenesis of feline infectious enteritis via parvoviruses

A

Killing of stem cells in crypts
Dehydration due to malabsorption can be fatal
High risk of secondary bacterial infection

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7
Q

Describe the pathogenesis of cerebellar hypoplasia via parvoviruses

A

Infection in neonatal kittens
Cerebellum controls coordination/balance => wobbly kittens

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8
Q

What are the clinical signs of feline parvovirus?

A

Pyrexia
Vomiting
Diarrhoea
Dehydration
Shock and sepsis (compromised intestinal mucosa)
High mortality rate
Sudden death

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9
Q

What is the treatment for feline parvovirus?

A

fluids to support circulation/hydration
antibiotics to reduce sepsis risk

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10
Q

Describe the control of feline parvovirus

A

Maternally derives antibody wanes after ~8wks
Vaccination ~6wks
Prevent exposure

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11
Q

How can you confirm diagnosis of feline parvovirus?

A

Faeces contains virus:
- detects virus antigen (ELISA)
- detect virus DNA (PCR)
Detect antibody to virus in blood
Supportive evidence - marked leucopenia/neutropenia

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12
Q

Describe the pathogenesis of canine parvovirus (CPV-2)

A

Infects actively dividing cells
-Generalised neonatal disease
-Myocarditis in neonatal pups (goes to myocardium rather than cerebellum)
- Bone marrow => leukopenia
- Intestinal villi => enteritis => vomiting and haemorrhagic diarrhoea
- intestinal and mesenteric lymphoid tissues => immunosuppression

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13
Q

Describe heart failure due to myocarditis in canine parvovirus infection

A

Myocardial necrosis
Inclusion bodies in myocardial cells
Increased Inflammatory cells
Fibrosis
Massive enlargement of heart

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14
Q

Describe features of coronasviruses

A

+sense ssRNA
Enveloped
Commonly mutate
Survive well in environment and low pH - destroyed by disinfectants
Enteric and respiratory pathogens

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15
Q

What are the important porcine coronaviruses?

A

TGEV - transmissable gastroenteritis virus
EDV - porcine epidemic diarrhoea virus
PDCoV - porcine delta coronavirus

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16
Q

Describe the pathogenesis of TGEV (transmissible gastroenteritis virus) and EDV (porcine epidemic diarrhoea virus)

A

Highly contagious
Young pigs
Diarrhoea/vomiting
Rapid dehydration

17
Q

Describe coronaviruses in cattle

A

Betacoronaviruses => calf diarrhoea
Scour 4d - 3wks
Dehydration, acidosis, depression, fever
Can cause resp signs

18
Q

Describe canine coronavirus

A

Canine enteric CoV
Mild self-limiting diarrhoea
Lethargic and inappetant
Loos feaces +/- mucus and blood
Supportive treatment

19
Q

Describe feline coronavirus

A

Most = mild or subclinical enteritis
Some => feline infectious peritonitis

20
Q

Describe feline infectious peritonitis

A

Coronavirus replicates in macrophages
Immune complex formation
Vasculitis
=> effusions (Wet FIP) or pyogranulomatous lesions (Dry FIP)
Wet FIP:
- ascites in abdomen => pot belly
- pleural effusion in thorax => dyspnoea

21
Q

How are coronaviruses controlled?

A

hygiene
vaccines
removal of infected animals
maintenance of clean herd/housing

22
Q

Name the pestiviruses of veterinary impotance

A

Bovine viral diarrhoea
Border disease virus
Classical swine fever

23
Q

Describe the features of pestiviruses

A

+ve ssRNA genome
cytoplasmic replication
icosahedral capsid
enveloped

24
Q

Describe Bovine viral diarrhoea virus

A

Transplacental transmission
Diarrhoea
Decreased fertility/milk yield
Abortion
Congenital defects
Stunted calves
Immunosuppression
Mucosal disease

25
Q

Describe mucosal disease as a consequence of bovine viral diarrhoea virus

A

Only develops in persistent infected animals
Required presence of NCP (non-cytopathic) and CP (cytopathic) virus
CP viruses show marked tropism for GALT
Severe diarrhoea => fatal
Marked mucosal haemorrhage

26
Q

How is bovine viral diarrhoea virus controlled?

A

Eliminate persistently infected animals from herd
Maintain closed herd
OR
Maintenance of herd immunity so no naive cattle are infected BVD
Vaccination or deliberate infection

27
Q

What are the important genera in the family paramyxovirus

A
28
Q

Describe the features of paramyxovirus

A

Large enveloped virus
-ve sense ssRNA
sensitive to heat, detergent, desiccation
cytoplasmic replication
release by budding

29
Q

What are the notifiable viruses in the genera morbillivirus

A

Rinderpest virus
Peste despetits ruminants
Canine distemper

30
Q

Describe rinderpest

A

High infectious disease of cattle
Respiratory and alimentary tract disease
Very high morbidity and mortality

31
Q

What are the clinical signs of rinderpest

A

Nasal and oral discharge
Pyrexia
Oral and nasal erosions and ulcerations
Diarrhoea + mucus, blood and debris
Dehydration => death

32
Q

Describe pest de petit ruminants

A

Mucosal erosions and profuse diarrhoea

33
Q

Describe the pathology of canine distemper

A

Morbillivirus
Transmitted by direct contact
Virus replicates in upper resp tract
Spreads to tonsils/lymph nodes
Viraemia and systemic spread to epilthelia

34
Q

What are the clinical signs of canine distemper?

A

Pyrexia
depression
Ocular and nasal discharge
Cough
Vomiting
Diarrhoea
Hyperkeratosis of nose/pads
Neurological signs if immune response is poor

35
Q

Describe Newcastle disease

A

Avian paramyxovirus
Shed in excretions and secretion => aerosols
Mechanical transfer from carcasses
Common in wild birds

36
Q

Describe the different strains of newcastle disease virus

A

Ientogenic - mild inapparent infection
Mesogenis - mild resp disease

Neurotropic velogenic - acute, sever, fatal with resp and nervous signs
Viscerotropic velogenic - severe, fatal with haemorrhagic intestinal lesions, resp disease

37
Q

What are the membrane glycoproteins on viruses and their roles

A

Fusion/F protein - enables fusion and entry
Haemagglutinin/neuraminidase (HN) - enables virus attachment to cell receptor

38
Q

Describe the role of F proteins in virulence

A

synthesised as precursor (F0) and cleaved by host cell proteases to active forms (F1 and F2) - if not cleaved then virus cannot enter
Lentogenic strains - confined to GI and resp tracts where trypsin-like proteases are present
Velogenic strains - can be cleaved in many tissues by different proteases due to altered cleavage site

39
Q

Describe the control of newcastle disease

A

Biosecurity
Cull infected animals
Vaccination