This article is still under construction.

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:

• Subfamily: Paramyxovirinae:

• Subfamily: Pneumovirinae
  • 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)

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

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

• On line Paramyxoviridae lecture by P. Russell