Difference between revisions of "Paramyxoviridae"

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===[[Bovine Parainfluenza - 3 (PI-3)]]===
 
===[[Bovine Parainfluenza - 3 (PI-3)]]===
  
===Bovine Respiratory Syncytial Virus (BRSV)===
+
===[[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==
 
==Equine==

Revision as of 18:49, 13 October 2008



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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)

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

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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