Difference between revisions of "Paramyxoviridae"

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#REDIRECT[[:Category:Paramyxoviridae]]
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{{unfinished}}
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{{toplink
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|linkpage =Viruses
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|linktext =VIRUSES
 +
|pagetype=Bugs
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}}
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<br>
 +
 
 +
=Introduction=
 +
 
 +
=Morphology=
 +
*Single-stranded negative-sense unsegmented RNA virus
 +
*Reassortment and antigenic shift cannot occur
 +
*Spike proteins include
 +
**'''HN''' (Haemagglutinin and Neuraminidase)
 +
**'''F''' (Fusion glycoprotein), which allows the virus to fuse directly to the plasma membrane and release its RNA
 +
***F also causes syncitium to form, which aids diagnosis
 +
***Host antibody response to the F protein is the basis for vaccination
 +
 
 +
=Virulence=
 +
*Paramyxoviruses replicate in the epithelium of the upper respiratory tract as well as occasionally in the gut
 +
**Sites of spike protein cleavage
 +
*Virulence varies by virus, see below
 +
 
 +
=Types and Subtypes=
 +
Paramoyxoviridae was reclassified in 2000 to include 2 subfamilies and 5 genera:
 +
*''Paramoyxovirinae'':
 +
**[[Paramyxoviridae#Bovine Parainfluenza - 3 (PI-3)| Bovine Parainfluenza 3]]
 +
**[[Paramyxoviridae#Canine Parainfluenza - 2|Canine Parainfluenza 2]]
 +
**[[Paramyxoviridae#Murine Parainfluenza - 1 (Sendai virus)|Murine Parainfluenza 1 (Sendai virus)]]
 +
**[[Paramyxoviridae#Newcastle Disease Virus (NDV)|Newcastle Disease (NDV)]] - avian paramyxovirus serotype 1
 +
**Avian Paramyxoviruses serotypes 2-9
 +
**[[Paramyxoviridae#Reptilian Paramyxoviruses|Reptilian Paramyxoviruses]]
 +
**Mumps
 +
*'''Morbilliviruses'''
 +
**[[Paramyxoviridae#Canine Distemper Virus (CDV)|Canine Distemper (CDV)]]
 +
**Rinderpest
 +
**Pest de petit ruminant (PPR)
 +
**Measels
 +
**Seal virus - phocine distemper
 +
**Dolphin Morbillivirus
 +
**[[Paramyxoviridae#Hendra Virus|Hendra virus]]
 +
**[[Paramyxoviridae#Nipah Virus|Nipah virus]]
 +
*'''Pneumovirinae'''
 +
**[[Paramyxoviridae#Bovine Respiratory Syncytial Virus (BRSV)|Bovine Respiratory Syncytial Virus (BRSV)]]
 +
**Turkey Rhinotracheitis Virus
 +
 
 +
=Antigenic Variation=
 +
*Antigenic conservation allows some cross protection by vaccination:
 +
**Conservation of major virus-specific F/HN antigens means vaccines protect against '''all isolates''' of the same virus
 +
**Minor morbillivirus-specific epitopes on F allows some cross protection between '''canine distemper, measles, and rinderpest'''
 +
*Antigenic "fingerprinting" is possible for some viruses based on minor variable epitopes of HN, F and NP on specific isolates as detected by monoclonal antibodies
 +
**These are detected by immunostaining infected cells
 +
 
 +
=Paramyxoviridae by Species=
 +
 
 +
==Avian==
 +
===Newcastle Disease Virus (NDV)===
 +
====Hosts====
 +
*Gallinaceous birds, pigeons, parrots, finches
 +
*Subclinical carriers: ducks, ostriches
 +
*Causes conjunctivitis in humans
 +
====Pathogenesis====
 +
*Transmission via aerosol and direct contact
 +
*Disease ranges from subclinical [[Respiratory Viral Infections - Pathology|respiratory tract infections]] -> torticollis -> haemorrhages and death
 +
====Diagnosis====
 +
Two diagnostic tests currently exist:
 +
*Animal test:
 +
**Samples of trachea and gut of 20 birds are tested in eggs
 +
**'''HI''' using anti-NDV serum (to differentiate '''HA''' caused by [[Orthomyxoviridae#Avian Influenza|avian influenza]]
 +
**Virulence of isolate tested by the speed it kills chicks
 +
*DNA test (which will soon replace the animal test):
 +
**Sequencing the cleavage site of H gene
 +
**The more basic amino acids the more virulent the virus
 +
====Control====
 +
*Newcastle Disease is '''NOTIFIABLE'''
 +
*Isolation of stock
 +
*Vaccination of chickens and racing pigeons
 +
*Surveillance of imported exotic birds
 +
*Infected premises to be culled and firebreak cull if spread
 +
 
 +
==Canine==
 +
===Canine Parainfluenza - 2===
 +
*or Parainfluenza - 5
 +
*Infects '''dogs'''
 +
*May cause mild upper respiratory infection, [[Nasal Cavity Inflammatory - Pathology#Infectious causes of rhinitis|rhinitis]]
 +
**Virus shed for a short time only
 +
*Also part of kennel cough ([[Respiratory Viral Infections - Pathology#Infectious canine tracheitis|Infectious canine tracheitis]]), together with [[Bordetella bronchiseptica and Bordetella avium|''Bordetella bronchiseptica'']]
 +
*Control:
 +
**'''Live attenuated vaccine''' may be incorporated in multivalent vaccines
 +
***Immunity is short-lived
 +
***Only reduces severity of clinical signs
 +
 
 +
===Canine Distemper Virus (CDV)===
 +
*Hosts: dogs, ferrets, seals, lions, mink
 +
*Has been a major pathogen of dogs prior to vaccination
 +
*Variable mortality depending on virulence
 +
*May occur subclinically
 +
*Involvement of central nervous system generally results in death
 +
*'''Pathogenesis''':
 +
**Aerosol infection
 +
**Infects alveolar [[Macrophages - WikiBlood|macrophages]] or [[Oropharynx - Pathology|oropharynx]]
 +
**Multiplies in the bronchial and other lymph nodes, infects monocytes and dendritic cells
 +
**Viraemia
 +
**Spreads via monocytes to a variety of epithelium depending upon the strain of virus
 +
**[[Respiratory Viral Infections - Pathology#Canine distemper|Respiratory]] and alimentary tracts, skin and later (1-5 wk. post infection) to the brain
 +
*'''Clinical signs''':
 +
**Mucopurulent oculonasal discharge
 +
**Keratitis
 +
**[[Lungs Inflammatory - Pathology#Interstitial pneumonia|Interstitial pneumonia]]
 +
**Severe clinical pneumonia follows secondary infection with [[Bordetella bronchiseptica and Bordetella avium|''Bordetella bronchiseptica'']]
 +
**Smelly sometimes bloody diarrhoea
 +
**Eruptions on the skin including hyperkeratosis of the nose and pads (hardpad)
 +
**[[PNS Repsonses to Injury - Pathology#Segmental Demyelination|Demyelination]] (especially in cerebellum) -> incoordination or muscle tremors -> paralysis and coma or convulsions -> death
 +
**Encephalitis
 +
**Secondary pyogenic infections associated with immunosuppression and damage to epithelia
 +
**Recovered animals may have persistent or spasmodic chorea
 +
**The severity of the disease may vary; if enough neutralising antibody develops in the early stages, the virus maybe kept restricted largely to the lymph nodes.
 +
*'''Diagnosis''':
 +
**May present as series of infections
 +
**'''Immunocytochemistry''' of inclusion bodies
 +
***Intracytoplasmic inclusions may be found in most affected tissues
 +
***Inclusions persist longest in the brain (may be intranuclear) and the alveolar macrophages
 +
***Sections of fixed bronchial tissue, lung, macrophages, bladder may be used or nasal or conjunctival epithelium from live animals
 +
**Giant cells may be seen in the alveoli
 +
*'''Control''':
 +
**Live attenuated virus vaccines given at 10 and 12 weeks of age
 +
***Some now given at 7 and 10 weeks to allow socialisation
 +
**Homeopathic vaccines do not work
 +
**Live attenuated vaccines may kill some wildlife therefore '''Iscom vaccine''' is used in seal sanctuaries
 +
 
 +
*Can contribute to [[Respiratory Viral Infections - Pathology#In Dogs|Infectious canine tracheitis]]
 +
*May be involved in [[Pancreas Inflammatory - Pathology#Chronic interstitial pancreatitis|chronic interstitial pancreatitis]]
 +
*May cause [[Bones Developmental - Pathology#Retention of elongated primary trabeculae|growth retardation lattice]]
 +
*May also trigger latent [[Tissue cyst-forming coccidia|Toxoplasmosis]] due to suppressing effect on lymphoid tissue
 +
 
 +
==Bovine==
 +
===Bovine Parainfluenza - 3 (PI-3)===
 +
*Virulence varies with isolates
 +
*Cessation of [[Respiratory System General Introduction - Pathology#Mucociliary escalator|ciliary clearance]] and epithelial necrosis predisposes to secondary bacterial infections -> cough
 +
*May cause [[Respiratory Viral Infections - Pathology#Parainfluenza- 3|rhinitis]] of cattle
 +
*With other agents causes [[Respiratory Bacterial Infections - Pathology#Enzootic pneumonia of calves|calf pneumonia ]]
 +
**Together with managemental factors (overcrowding, poor ventilation, high humidity, deprivation of colostrum and stress caused by transport or mixing of stock)
 +
*'''Diagnosis'''
 +
**Diseased lung tissue from dead animals or centrifuged cells from lung lavage
 +
**Virus is too fragile for cell culture isolation (often inactivated intransport)
 +
**Antigen detection by ''' immunocytochemistry''' for intracytoplasmic viral inclusions containing labelled viral protein
 +
**Serology: 4-fold rise in ELISA antibody in paired serum samples from several animals
 +
*'''Control'''
 +
**Improve managemental factors
 +
**All-in, all-out systems
 +
**Some vaccination
 +
***Temperature sensitive mutant that replicates at 34<sup>o</sup>C but not at 37<sup>o</sup>C
 +
***Re-infection is common
 +
 
 +
===Bovine Respiratory Syncytial Virus (BRSV)===
 +
*'''Pathogenesis''':
 +
**More serious than [[Paramyxoviridae#Parainfluenza -3 (PI-3)|PI-3]]
 +
**Causes [Respiratory Viral Infections - Pathology#Respiratory syncytial virus|respiratory infection]]
 +
**Replicates in nasal epithelium -> throughout upper respiratory tract -> bronchial tree
 +
**Syncytia form -> shed into bronchioles
 +
**Complications include [[Lungs Ventilation - Pathology#Emphysema|emphysema]] and [[Lungs Circulatory - Pathology#Pulmonary oedema|oedema]], drop in milk yield in adult cattle
 +
*'''Epidemiology''':
 +
**Subclinical reinfections are important in spreading disease
 +
**More than 70% of cattle in the UK have antibodies to BRSV
 +
*'''Diagnosis''' is same as for [[Paramyxoviridae#Parainfluenza -3 (PI-3)|PI-3]]
 +
*'''Control'''
 +
**Improve husbansry as in [[Paramyxoviridae#Parainfluenza -3 (PI-3)|PI-3]]
 +
**Vaccines are available but not effective as need to stimulate [[Lymphocytes - WikiBlood#Cytotoxic CD8+|cytotoxic T-cells]]
 +
*<small>'''Reference''': Bryson, 1999, Update on calf pneumonia, CPD Veterinary Medicine, 1,3, 90-95</small>
 +
 
 +
==Equine==
 +
===Hendra Virus===
 +
*Equine Paramyxovirus
 +
*Causes [[Respiratory Viral Infections - Pathology#Hendra virus|respiratory infections]] with respiratory distress and paralysis
 +
*Potentially zoonotic (beware palpating inside the throat for obstruction)
 +
 
 +
==Porcine==
 +
===Nipah Virus===
 +
*Infects pigs and humans
 +
*Humans exposed to pig blood are at risk
 +
 
 +
==Reptiles==
 +
===Reptilian Paramyxoviruses===
 +
*Infect central nervous system and lungs
 +
*Kill particularly '''snakes'''
 +
*Healthy reptiles may be carriers
 +
*Testing by serology - '''HI test'''
 +
*Aim to keep virus free collection and prevent spread back into the wild
 +
 
 +
==Rodentia==
 +
===Murine Parainfluenza - 1 (Sendai virus)===
 +
*Endemic in many '''mouse''' colonies
 +
*Most mice show no symptoms due to maternal antibodies
 +
*But minor respiratory lesions may invalidate carcinogenic or toxicological studies
 +
*Immunological studies also confused due to virus activating [[Lymphocytes - WikiBlood#Natural Killer (NK) Cells|NK cells]] via high circulating [[Innate Immune System - WikiBlood#Interferons|IF]] 3-4 days post-infection
 +
*Control achieved by:
 +
**Purchasing specific pathogen free (SPF) mice
 +
**Kill whole colony in an outbreak -> disinfection -> formalin fumigation
 +
 
 +
=Other resources=
 +
*[http://www.pitt.edu/~super1/lecture/lec3401/index.htm On line Paramyxoviridae lecture by P. Russell]
 +
 
 +
 
 +
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Revision as of 20:07, 12 October 2008


 This article is still under construction.


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VIRUSES



Introduction

Morphology

  • Single-stranded negative-sense unsegmented RNA virus
  • Reassortment and antigenic shift cannot occur
  • Spike proteins include
    • HN (Haemagglutinin and Neuraminidase)
    • F (Fusion glycoprotein), which allows the virus to fuse directly to the plasma membrane and release its RNA
      • F also causes syncitium to form, which aids diagnosis
      • Host antibody response to the F protein is the basis for vaccination

Virulence

  • Paramyxoviruses replicate in the epithelium of the upper respiratory tract as well as occasionally in the gut
    • Sites of spike protein cleavage
  • Virulence varies by virus, see below

Types and Subtypes

Paramoyxoviridae was reclassified in 2000 to include 2 subfamilies and 5 genera:

Antigenic Variation

  • Antigenic conservation allows some cross protection by vaccination:
    • Conservation of major virus-specific F/HN antigens means vaccines protect against all isolates of the same virus
    • Minor morbillivirus-specific epitopes on F allows some cross protection between canine distemper, measles, and rinderpest
  • Antigenic "fingerprinting" is possible for some viruses based on minor variable epitopes of HN, F and NP on specific isolates as detected by monoclonal antibodies
    • These are detected by immunostaining infected cells

Paramyxoviridae by Species

Avian

Newcastle Disease Virus (NDV)

Hosts

  • Gallinaceous birds, pigeons, parrots, finches
  • Subclinical carriers: ducks, ostriches
  • Causes conjunctivitis in humans

Pathogenesis

  • Transmission via aerosol and direct contact
  • Disease ranges from subclinical respiratory tract infections -> torticollis -> haemorrhages and death

Diagnosis

Two diagnostic tests currently exist:

  • Animal test:
    • Samples of trachea and gut of 20 birds are tested in eggs
    • HI using anti-NDV serum (to differentiate HA caused by avian influenza
    • Virulence of isolate tested by the speed it kills chicks
  • DNA test (which will soon replace the animal test):
    • Sequencing the cleavage site of H gene
    • The more basic amino acids the more virulent the virus

Control

  • Newcastle Disease is NOTIFIABLE
  • Isolation of stock
  • Vaccination of chickens and racing pigeons
  • Surveillance of imported exotic birds
  • Infected premises to be culled and firebreak cull if spread

Canine

Canine Parainfluenza - 2

  • or Parainfluenza - 5
  • Infects dogs
  • May cause mild upper respiratory infection, rhinitis
    • Virus shed for a short time only
  • Also part of kennel cough (Infectious canine tracheitis), together with Bordetella bronchiseptica
  • Control:
    • Live attenuated vaccine may be incorporated in multivalent vaccines
      • Immunity is short-lived
      • Only reduces severity of clinical signs

Canine Distemper Virus (CDV)

  • Hosts: dogs, ferrets, seals, lions, mink
  • Has been a major pathogen of dogs prior to vaccination
  • Variable mortality depending on virulence
  • May occur subclinically
  • Involvement of central nervous system generally results in death
  • Pathogenesis:
    • Aerosol infection
    • Infects alveolar macrophages or oropharynx
    • Multiplies in the bronchial and other lymph nodes, infects monocytes and dendritic cells
    • Viraemia
    • Spreads via monocytes to a variety of epithelium depending upon the strain of virus
    • Respiratory and alimentary tracts, skin and later (1-5 wk. post infection) to the brain
  • Clinical signs:
    • Mucopurulent oculonasal discharge
    • Keratitis
    • Interstitial pneumonia
    • Severe clinical pneumonia follows secondary infection with Bordetella bronchiseptica
    • Smelly sometimes bloody diarrhoea
    • Eruptions on the skin including hyperkeratosis of the nose and pads (hardpad)
    • Demyelination (especially in cerebellum) -> incoordination or muscle tremors -> paralysis and coma or convulsions -> death
    • Encephalitis
    • Secondary pyogenic infections associated with immunosuppression and damage to epithelia
    • Recovered animals may have persistent or spasmodic chorea
    • The severity of the disease may vary; if enough neutralising antibody develops in the early stages, the virus maybe kept restricted largely to the lymph nodes.
  • Diagnosis:
    • May present as series of infections
    • Immunocytochemistry of inclusion bodies
      • Intracytoplasmic inclusions may be found in most affected tissues
      • Inclusions persist longest in the brain (may be intranuclear) and the alveolar macrophages
      • Sections of fixed bronchial tissue, lung, macrophages, bladder may be used or nasal or conjunctival epithelium from live animals
    • Giant cells may be seen in the alveoli
  • Control:
    • Live attenuated virus vaccines given at 10 and 12 weeks of age
      • Some now given at 7 and 10 weeks to allow socialisation
    • Homeopathic vaccines do not work
    • Live attenuated vaccines may kill some wildlife therefore Iscom vaccine is used in seal sanctuaries

Bovine

Bovine Parainfluenza - 3 (PI-3)

  • Virulence varies with isolates
  • Cessation of ciliary clearance and epithelial necrosis predisposes to secondary bacterial infections -> cough
  • May cause rhinitis of cattle
  • With other agents causes calf pneumonia
    • Together with managemental factors (overcrowding, poor ventilation, high humidity, deprivation of colostrum and stress caused by transport or mixing of stock)
  • Diagnosis
    • Diseased lung tissue from dead animals or centrifuged cells from lung lavage
    • Virus is too fragile for cell culture isolation (often inactivated intransport)
    • Antigen detection by immunocytochemistry for intracytoplasmic viral inclusions containing labelled viral protein
    • Serology: 4-fold rise in ELISA antibody in paired serum samples from several animals
  • Control
    • Improve managemental factors
    • All-in, all-out systems
    • Some vaccination
      • Temperature sensitive mutant that replicates at 34oC but not at 37oC
      • Re-infection is common

Bovine Respiratory Syncytial Virus (BRSV)

  • Pathogenesis:
    • More serious than PI-3
    • Causes [Respiratory Viral Infections - Pathology#Respiratory syncytial virus|respiratory infection]]
    • Replicates in nasal epithelium -> throughout upper respiratory tract -> bronchial tree
    • Syncytia form -> shed into bronchioles
    • Complications include emphysema and oedema, drop in milk yield in adult cattle
  • Epidemiology:
    • Subclinical reinfections are important in spreading disease
    • More than 70% of cattle in the UK have antibodies to BRSV
  • Diagnosis is same as for PI-3
  • Control
    • Improve husbansry as in PI-3
    • Vaccines are available but not effective as need to stimulate cytotoxic T-cells
  • Reference: Bryson, 1999, Update on calf pneumonia, CPD Veterinary Medicine, 1,3, 90-95

Equine

Hendra Virus

  • Equine Paramyxovirus
  • Causes respiratory infections with respiratory distress and paralysis
  • Potentially zoonotic (beware palpating inside the throat for obstruction)

Porcine

Nipah Virus

  • Infects pigs and humans
  • Humans exposed to pig blood are at risk

Reptiles

Reptilian Paramyxoviruses

  • Infect central nervous system and lungs
  • Kill particularly snakes
  • Healthy reptiles may be carriers
  • Testing by serology - HI test
  • Aim to keep virus free collection and prevent spread back into the wild

Rodentia

Murine Parainfluenza - 1 (Sendai virus)

  • Endemic in many mouse colonies
  • Most mice show no symptoms due to maternal antibodies
  • But minor respiratory lesions may invalidate carcinogenic or toxicological studies
  • Immunological studies also confused due to virus activating NK cells via high circulating IF 3-4 days post-infection
  • Control achieved by:
    • Purchasing specific pathogen free (SPF) mice
    • Kill whole colony in an outbreak -> disinfection -> formalin fumigation

Other resources


BACK TO VIRUSES
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