Difference between revisions of "Paramyxoviridae"

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*Infects pigs and humans
 
*Infects pigs and humans
 
*Humans exposed to pig blood are at risk
 
*Humans exposed to pig blood are at risk
 +
*Causes porcine respiratory and neurologic syndrome in pigs
 +
*Zoonosis transmitted by fruit bats
 +
*Nipah virus is an emerging disease with the first outbreak in 1999 in Malaysia
  
 
==Reptiles==
 
==Reptiles==

Revision as of 08:18, 6 September 2009



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VIRUSES



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, of interest including:

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)

Canine

Canine Parainfluenza - 2 (aka Parainfluenza - 5)

Canine Distemper Virus (CDV)

Bovine

Bovine Parainfluenza - 3 (PI-3)

Bovine Respiratory Syncytial Virus (BRSV)

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
  • Causes porcine respiratory and neurologic syndrome in pigs
  • Zoonosis transmitted by fruit bats
  • Nipah virus is an emerging disease with the first outbreak in 1999 in Malaysia

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


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