Difference between revisions of "Paramyxoviridae"

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#REDIRECT[[:Category:Paramyxoviridae]]
 
 
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=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)]]===
 
 
 
==Canine==
 
===[[Canine Parainfluenza - 2 (aka Parainfluenza - 5)]]===
 
 
 
===[[Canine Distemper Virus (CDV)]]===
 
 
 
==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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Latest revision as of 10:52, 22 May 2010