Viruses and GI disease

Question 1

Describe the features of parvoviruses

Answer 1

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

Question 2

Which parvoviruses are of veterinary importance?

Answer 2

Question 3

Describe the effect of parvovirus in the villi of the SI

Answer 3

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

Question 4

Describe Feline infectious enteritis/feline panleukopenia

Answer 4

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

Question 5

Describe the pathogenesis of feline panleukopenia via parvoviruses

Answer 5

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

Question 6

Describe the pathogenesis of feline infectious enteritis via parvoviruses

Answer 6

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

Question 7

Describe the pathogenesis of cerebellar hypoplasia via parvoviruses

Answer 7

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

Question 8

What are the clinical signs of feline parvovirus?

Answer 8

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

Question 9

What is the treatment for feline parvovirus?

Answer 9

fluids to support circulation/hydration
antibiotics to reduce sepsis risk

Question 10

Describe the control of feline parvovirus

Answer 10

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

Question 11

How can you confirm diagnosis of feline parvovirus?

Answer 11

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

Question 12

Describe the pathogenesis of canine parvovirus (CPV-2)

Answer 12

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

Question 13

Describe heart failure due to myocarditis in canine parvovirus infection

Answer 13

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

Question 14

Describe features of coronasviruses

Answer 14

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

Question 15

What are the important porcine coronaviruses?

Answer 15

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

Question 16

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

Answer 16

Highly contagious
Young pigs
Diarrhoea/vomiting
Rapid dehydration

Question 17

Describe coronaviruses in cattle

Answer 17

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

Question 18

Describe canine coronavirus

Answer 18

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

Question 19

Describe feline coronavirus

Answer 19

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

Question 20

Describe feline infectious peritonitis

Answer 20

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

Question 21

How are coronaviruses controlled?

Answer 21

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

Question 22

Name the pestiviruses of veterinary impotance

Answer 22

Bovine viral diarrhoea
Border disease virus
Classical swine fever

Question 23

Describe the features of pestiviruses

Answer 23

+ve ssRNA genome
cytoplasmic replication
icosahedral capsid
enveloped

Question 24

Describe Bovine viral diarrhoea virus

Answer 24

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

Question 25

Describe mucosal disease as a consequence of bovine viral diarrhoea virus

Answer 25

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

Question 26

How is bovine viral diarrhoea virus controlled?

Answer 26

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

Question 27

What are the important genera in the family paramyxovirus

Answer 27

Question 28

Describe the features of paramyxovirus

Answer 28

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

Question 29

What are the notifiable viruses in the genera morbillivirus

Answer 29

Rinderpest virus Peste despetits ruminants Canine distemper

Question 30

Describe rinderpest

Answer 30

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

Question 31

What are the clinical signs of rinderpest

Answer 31

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

Question 32

Describe pest de petit ruminants

Answer 32

Mucosal erosions and profuse diarrhoea

Question 33

Describe the pathology of canine distemper

Answer 33

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

Question 34

What are the clinical signs of canine distemper?

Answer 34

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

Question 35

Describe Newcastle disease

Answer 35

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

Question 36

Describe the different strains of newcastle disease virus

Answer 36

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

Question 37

What are the membrane glycoproteins on viruses and their roles

Answer 37

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

Question 38

Describe the role of F proteins in virulence

Answer 38

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

Question 39

Describe the control of newcastle disease

Answer 39

Biosecurity Cull infected animals Vaccination