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Infectious Diseases 2 > Asfarviridae & Adenoviridae > Flashcards

Asfarviridae & Adenoviridae Flashcards

1
Q

What does Asfarviridae stand for?

A 
African
Swine
Fever
And 
Related viruses
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2
Q

Describe Asfarviridae…

A
  • Only one virus species in the whole family
  • dsDNA
  • Cytoplasmic replication
  • Large and complex
  • Enveloped
  • Highly resistant to wide pH range (4-15)
  • Survives for months-years in refrigerated meat
  • Only DNA virus that is an arbovirus (transmitted by ticks)
  • Causes lethal haemorrhagic disease in pigs
  • List A OIE notifiable disease
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3
Q

What is an arbovirus?

A

Term used to refer to viruses that are transmitted by arthropods

  • need to replicate within the nucleus of these vector’s cells
    e. g. ticks
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4
Q

Is African Swine Fever notifiable in NZ?

A

Yes

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5
Q

Describe African Swine Fever…

A
  • Infects all members of the family Suidae
  • Highly contagious lethal disease of pigs
  • Asymptomatic in warthogs
  • Clinical and post mortem signs are indistinguishable from classical swine fever (totally different family and also has a vaccine)
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6
Q

How far has African Swine Fever spread in less than a decade?

A

Across western Russia

- worrying because Russia is so close to Europe

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7
Q

Describe the epizootiology of African Swine Fever…

A

It has two different epidemiological patterns - transferred by ticks

  • Sylvatic (circulates in wild animals only) cycle in wild african swine
  • Epidemic and endemic cycles in domestic swine
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8
Q

Describe the Sylvatic cycle of ASF…

A

The virus cycles between the hosts: Wild pigs, domestic pigs and ticks
- Need a suitable vector for the disease to become enzootic in an area

Sexual transmission within the ticks
- mother to eggs
- from one virus developmental stage to another
Tick population is 25% infected

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9
Q

What symptoms do wild pigs show when infected with ASF?

A

None

  • Asymptomatic
  • Persistent Infection in wild pigs and ticks
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10
Q

How are pigs initially infected with ASF?

A
  • Tick bites
    OR
  • Ingestion / inhalation of infected material
  • Feeding uncooked pig meat
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11
Q

How do infected pigs spread ASF?

A

They produce large amounts of virus in all body secretions and excretions

  • Spread by:
    • Aerosol
    • Direct contact
    • People
    • Vehicles
    • Other
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12
Q

If a pig recovers from ASF are they still infectious?

A

They remain carriers and shed the virus for their entire lives but don’t show clinical signs

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13
Q

What are the three forms of ASF clinical signs?

A
  1. Acute
  2. Subacute
  3. Chronic
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14
Q

What are ASF clinical signs?

A
  • Bloody diarrhoea
  • Hind leg paralysis
  • Huddling
  • Conjunctivitis
  • Purple decolourisation on rump
  • Staggering
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15
Q

What are some DDx for ASF?

A
  • Classical Swine Fever
  • Erysipelas
  • Porcine dermatitis and nephropathy syndrome
  • Salmonellosis
  • Pasteurellosis
  • All Septicaemic conditions
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16
Q

What samples do you collect for lab diagnosis of ASF?

A
  • Tissues: spleen, kidney, liver, lymph nodes
  • Anticoagulated blood for virus isolation
  • Clotted blood for serology
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17
Q

How do you detect ASF or ASF components?

A
  • Virus isolation (blood, spleen, kidney, liver)
  • Fluorescent antibody test
  • PCR
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18
Q

What serology tests do you need to diagnose ASF?

A
  • Antiobodies to ASF appear 7-12 dots per inch
  • No neutralisation
  • No known cross-reactivity
  • ELISA
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19
Q

Describe the pathogenesis of ASF…

A

Disseminated intravascular coagulation (DIC) with multiple haemorrhages in all tissues

  • ASF replicates in macrophages and monocytes
  • Modulation of signalling pathways in infected macrophages
    • expression of a number of viral immunomodulatory (capable of modifying immune functions) proteins
20
Q

Are neutralising antibodies made by pigs?

A

No

- not even in pigs that survive

21
Q

Is there a vaccine available for ASF?

A

No not yet

22
Q

How do you control ASF outbreaks?

A
  • Difficult to control
  • No vaccine
  • Exclude wild pigs from domestic piggeries in enzootic areas
  • Use tick killers and disinfectants
  • Slaughter if spreads to unaffected country
  • Burn carcasses
23
Q

What are the risks of ASF to NZ?

A
  • Imported frozen pig meat
  • Imported live pigs
  • Swill from passenger air crafts
  • Ticks
  • Wild pigs
24
Q

Describe adenoviral replication…

A
  • Replicate in the nucleus
  • Produce intranuclear inclusion bodies - crystalline arrays of virions
  • Virions release by cell lysis
  • “Bunch of Grapes” cytoplasmic effects
25
Q

Describe the structure of Adenoviruses…

A
  • Penton fibres project from icosahedral vertices
  • Each fibre has a terminal knob
  • These knobs stick together some mammalian RBCs
    • can use haemagglutination test (HA)
26
Q

What are some common properties of Adenoviruses?

A
  • Resistant in the environment
  • Readily transmitted on fomites
  • Provoke strong humoral immune responses
  • Can persist for a long period
  • Widespread
  • Host Specific
  • Relatively non-pathogenic
  • Can cause disease in immunocompromised hosts
  • Some are oncogenic in rodents
  • Infect cells in respiratory and GI tracts
27
Q

Where can adenoviruses persist for long periods?

A
  • Pharyngeal lymphoid tissues
  • Kidney tubule cells
  • Intestinal cells
28
Q

What are some diseases caused by adenoviruses?

A
  • Canine adenoviruses 1 and 2
  • Equine adenoviruses
  • Egg drop syndrome
  • Inclusion body hepatitis
  • Haemorrhagic enteritis of turkeys
  • Marble spleen disease of pheasants
  • Quail Bronchitis
29
Q

What are the names for canine adenoviruses 1 and 2?

A
    • Infectious canine hepatitis (CAdV-1)

- - Respiratory Disease (CAdV-2)

30
Q

Describe Canine Adenovirus 1…

A

Infectious canine hepatitis

  • Dogs (puppies espec) , foxes, wolves. coyotes, skunks, bears are susceptible
  • Acute hepatitis
  • Many subclinical infections occur
31
Q

Describe the infection of CAdV-1…

A
  • Infection by nasopharyngeal, oral or conjunctival routes
  • Local replication in tonsils or Peyer’s patches
  • Spread to many tissues
  • Replication
  • Transmission
  • Excretion in faeces, saliva and urine
  • Endothelial cells cause haemorrhages
  • Parenchymal cells cause necrotic lesions
32
Q

What is peracute CAdV-1 disease?

A

Death in 3-4 hours

No symptoms

33
Q

What is acute CAdV-1?

A
  • Incubation period of 4-9 days
  • Fever
  • Depression
  • Loss of appetite
  • Vomiting
  • Abdominal pain
  • Tachycardia
  • Leukopenia
  • Prolonged clotting time
  • DIC
  • Bloody Diarrhoea
  • Petechial haemorrhages on gums
  • Pale Mucous Membranes
  • May be Fatal
34
Q

What is “blue eye”?

A

Corneal Opacity that develops in 25% of dogs with acute CAdV-1

  • develops 7-10 days after apparent recovery
  • usually disappears spontaneously
35
Q

What is the mortality rate in dogs with CAdV-1?

A

Puppies: 100% mortality
Adults: 10-30% mortality

36
Q

Do dogs that have recovered from CAdV-1 shed the virus?

A

Yes

  • for several months
  • especially in urine
37
Q

How is CAdV-1 diagnosed?

A
  • Clinical Signs
  • Clinical Pathology
  • Gross Pathology
  • Histopathology
  • Rising antibody titres
  • Virus Isolation
  • Viral Antigen in tissues
  • Viral DNA in PCR
38
Q

What is CAdV-2 a contributing factor to?

A

Infectious canine laryngotracheitis (kennel cough)

39
Q

Describe the vaccination against CAdV-1…

A

Inactivated vaccine

- Live attenuated no longer used because of complications

40
Q

Describe the vaccination against CAdV-2…

A

Live Attenuated

- also protects against CAdV-1 (cross-protection) because their antigenic properties are similar

41
Q

Describe Equine Adenoviruses….

A
  • Most infections are asymptomatic
  • May contribute to equine respiratory disease
    • fever, depression, nasal discharge, cough
    • Self- limiting
42
Q

What is SCID?

A

Severe combined immunodeficiency

  • Absence of both T and B cells
  • Destruction of cells in many tissues and multi-organ failure
  • Death at ~3 months old
43
Q

What are the clinical features of acute ASF?

A
  • Fever
  • Early leucopaenia and thrombocytopaenia
  • Reddening of skin extremities
  • Anorexia, listlessness, cyanosis, incoordination
  • Increased pulse and RR
  • Vomiting, diarrhoea and eye discharges
  • Death up to 20 days
44
Q

What are the clinical features of subacute ASF?

A
  • Less severe clinical signs
  • 5-30 duration
  • Abortion in pregnant sows
  • Death within 15-45 days
  • Low mortality rate
45
Q

What are the clinical features of chronic ASF?

A
  • Weightloss
  • Irregular peaks of temperature
  • Respiratory signs
  • Necrosis in areas of skin
  • Chronic skin ulcers
  • Arthritis
  • Pericarditis
  • Adhesions of lungs
  • Swelling over joints
  • Develops over 2-15 months
  • Low mortality

Infectious Diseases 2 (9 decks)

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