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*Single-stranded negative-sense unsegmented RNA virus
*Single-stranded negative-sense unsegmented RNA virus
*Reassortment and antigenic shift cannot occur
*Reassortment and antigenic shift cannot occur
*Spike proteins include '''HN''' (Haemagglutinin and Neuraminidase) and '''F''' (Fusion glycoprotein), which allows the virus to fuse directly to the plasma membrane and release its RNA
*Spike proteins include
**F also causes syncitium to form, which aids diagnosis
**'''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=
=Virulence=
*Paramyxoviruses replicate in the epithelium of the upper respiratory tract as well as occasionally in the gut
*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=
=Types and Subtypes=
Paramoyxoviridae was reclassified in 2000 to include 2 subfamilies and 5 genera:
*''Paramoyxovirinae'':
*Systemic infections - controlled by '''live monotypic vaccination'''
**[[Paramyxoviridae#Bovine Parainfluenza - 3 (PI-3)| Bovine Parainfluenza 3]]
**[[Paramyxoviridae#Bovine Parainfluenza - 3 (PI-3)| Bovine Parainfluenza 3]]
**[[Paramyxoviridae#Canine Parainfluenza - 2|Canine Parainfluenza 2]]
**[[Paramyxoviridae#Canine Parainfluenza - 2|Canine Parainfluenza 2]]
**Turkey Rhinotracheitis Virus
**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
===Virus properties===
=Paramyxoviridae by Species=
==Avian==
===Newcastle Disease Virus (NDV)===
===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
*'''Virulence'''
*Disease ranges from subclinical [[Respiratory Viral Infections - Pathology|respiratory tract infections]] -> torticollis -> haemorrhages and death
====Diagnosis====
Two diagnostic tests currently exist:
*Animal test:
**Air-born
**Samples of trachea and gut of 20 birds are tested in eggs
**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]]
**'''HI''' using anti-NDV serum (to differentiate '''HA''' caused by [[Orthomyxoviridae#Avian Influenza|avian influenza]]
**Animal test: virulence of isolate tested by the speed it kills chicks
**Virulence of isolate tested by the speed it kills chicks
**Sequencing the cleavage site of [[Paramyxoviridae#Structure|H]] gene
*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====
*'''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===
===Canine Parainfluenza - 2===
*or Parainfluenza - 5
*or Parainfluenza - 5
*Infects dogs
*Infects '''dogs'''
*May cause mild upper respiratory infection, [[Nasal Cavity Inflammatory - Pathology#Infectious causes of rhinitis|rhinitis]]
*May cause mild upper respiratory infection, [[Nasal Cavity Inflammatory - Pathology#Infectious causes of rhinitis|rhinitis]]
**Virus shed for a short time only
**Virus shed for a short time only
***Immunity is short-lived
***Immunity is short-lived
***Only reduces severity of clinical signs
***Only reduces severity of clinical signs
===Canine Distemper Virus (CDV)===
===Canine Distemper Virus (CDV)===
*Hosts: dogs, ferrets, seals, lions, mink
*Hosts: dogs, ferrets, seals, lions, mink
*Has been a major pathogen of dogs prior to vaccination
*Has been a major pathogen of dogs prior to vaccination
*May also trigger latent [[Tissue cyst-forming coccidia|Toxoplasmosis]] due to suppressing effect on lymphoid tissue
*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===
===Hendra Virus===
*Equine Paramyxovirus
*Equine Paramyxovirus
*Causes [[Respiratory Viral Infections - Pathology#Hendra virus|respiratory infections]] with respiratory distress and paralysis
*Causes [[Respiratory Viral Infections - Pathology#Hendra virus|respiratory infections]] with respiratory distress and paralysis
*Potentially zoonotic (beware palpating inside the throat for obstruction)
*Potentially zoonotic (beware palpating inside the throat for obstruction)
==Porcine==
===Nipah Virus===
===Nipah Virus===
*Infects pigs and humans
*Infects pigs and humans
*Humans exposed to pig blood are at risk
*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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