Difference between revisions of "Paramyxoviridae"

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#REDIRECT[[:Category:Paramyxoviridae]]
 
 
 
 
===Overview===
 
 
 
*Systemic infections - controlled by '''live monotypic vaccination'''
 
*Respiratory infections - ''not'' controled by '''live monotypic vaccinations'''
 
*[http://www.pitt.edu/~super1/lecture/lec3401/index.htm On line Paramyxoviridae lecture by P. Russell]
 
 
 
 
 
===Classification===
 
 
 
*'''Paramyxovirinae'''
 
**[[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
 
 
 
 
 
===Virus properties===
 
 
 
====Structure====
 
 
 
*Negative sense '''RNA''', unsegmented, single stranded
 
**-> '''Reasortment''' and '''antigenic shift''' cannot occur
 
*'''HN spike''' contains:
 
**'''Haemagglutinin (H)'''- attachment protein
 
**'''Neuraminidase (N)'''
 
*'''Fusion''' glycoprotein (F) spike
 
**-> Viral lipid bilayer can fuse directly with host plasma membrane
 
***-> RNA released into cytoplasm
 
**->Syncytium (multinucleated giant cells) in lesions and cell culture
 
**Host antibody response to this protein is most important
 
***Best induced by '''live attenuated vaccines'''
 
 
 
====Growth ''in vitro''====
 
 
 
*Allantoic cavity of 10-day-old eggs
 
*Followed by '''haemagglutination'''
 
 
 
====''In vivo''====
 
 
 
*Cell tropism for upper respiratory tract epithelium
 
**All replicate in these cells
 
*Some replicate in the gut
 
*Most virulent replicate in lymphoid cells and neurons ([[Paramyxoviridae#Canine Distemper Virus (CDV)|Distemper]], [[Paramyxoviridae#Newcastle Disease Virus (NDV)|NDV]])
 
*Links to the readiness to cleave Fo and Ho precursors in different cells
 
 
 
====Antigenic differentiation====
 
 
 
*Major conserved immunodominant virus-specific antigens on [[Paramyxoviridae#Structure|F and HN]]
 
**-> Vaccines protect against all isolates of the same virus
 
*Minor morbillivirus-specific epitopes on [[Paramyxoviridae#Structure|F]]
 
**Some crossprotectin between [[Paramyxoviridae#Canine Distemper Virus (CDV)|canine distemper]], measels and rinderpest
 
*Minor variable epitopes of [[Paramyxoviridae#Structure|F, HN and '''NP''']]
 
**Allows antigenic '''fingerprinting'''
 
 
 
 
 
===Newcastle Disease Virus (NDV)===
 
 
 
*'''Hosts'''
 
**Gallinaceous birds, pigeons, parrots, finches
 
**Subclinical carriers: ducks, ostriches
 
**Causes conjunctivitis in humans
 
 
 
*'''Virulence'''
 
**Disease ranges from subclinical [[Viral infections|respiratory tract infections]] -> torticollis -> haemorrhages and death
 
 
 
*'''Epidemiology'''
 
**Air-born
 
**Direct contact of poultry
 
 
 
*'''Diagnosis'''
 
**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]]
 
**Animal test: virulence of isolate tested by the speed it kills chicks
 
**Sequencing the cleavage site of [[Paramyxoviridae#Structure|H]] gene
 
***The more basic amino acids the more virulent the virus
 
***Now replacing the animal test
 
 
 
*'''Control'''
 
**Isolation of stock
 
**Vaccination of chickens and racing pigeons
 
**Surveillance of imported exotic birds
 
**Notifiable disease
 
**Infected premises to be culle and firebreak cull if spread
 
 
 
 
 
===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
 
 
 
 
 
===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 [[General Pathology - Antigen Recognition, Processing and Presentation#NK Receptors|NK cells]] via high circulating [[General Pathology - Innate Immunity#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
 
 
 
 
 
===Canine Parainfluenza - 2===
 
 
 
*or Parainfluenza - 5
 
*Infects dogs
 
*May cause mild upper respiratory infection, [[Nasal cavity - inflammatory#Infectious causes of rhinitis|rhinitis]]
 
**Virus shed for a short time only
 
*Also part of kennel cough ([[Viral infections#Infectious canine tracheitis|Infectious canine tracheitis]]), together with [[Bordetella bronchiseptica and Bordetella avium|''Bordetella bronchiseptica'']]
 
*Control:
 
**'''Live attenuated vaccine''' may be incorporated in multivalent vaccines
 
***Immunity is short-lived
 
***Only reduces severity of clinical signs
 
 
 
 
 
===Bovine Parainfluenza - 3 (PI-3)===
 
 
 
*Virulence varies with isolates
 
*Cessation of [[Respiratory system - general introduction#Mucociliary escalator|ciliary clearance]] and epithelial necrosis predisposes to secondary bacterial infections -> cough
 
*May cause [[Viral infections#Parainfluenza- 3|rhinitis]] of cattle
 
*With other agents causes [[Bacterial infections#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 [Viral infections#Respiratory syncytial virus|respiratory infection]]
 
**Replicates in nasal epithelium -> throughout upper respiratory tract -> bronchial tree
 
**Syncytia form -> shed into bronchioles
 
**Complications include [[Lungs - ventilation#Emphysema|emphysema]] and [[Lungs - circulatory#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 [[General Pathology - T-cell Activation and Function#Cytotoxic T-Cells|cytotoxic T-cells]]
 
*<small>'''Reference''': Bryson, 1999, Update on calf pneumonia, CPD Veterinary Medicine, 1,3, 90-95</small>
 
 
 
 
 
===Canine Distemper Virus (CDV)===
 
 
 
*Hosts: dogs, ferrets, seals, lions, mink
 
*Has been a major pathogen of dogs prior to vaccination
 
*Variable mortality depending on virulence
 
*May occur subclinically
 
*Involvement of central nervous system generally results in death
 
*'''Pathogenesis''':
 
**Aerosol infection
 
**Infects alveolar [[Macrophages - Anatomy & Physiology|Macrophages]] or [[Oral Cavity - Oropharynx|oropharynx]]
 
**Multiplies in the bronchial and other lymph nodes, infects monocytes and dendritic cells
 
**Viraemia
 
**Spreads via monocytes to a variety of epithelium depending upon the strain of virus
 
**[[Viral infections#Canine distemper|Respiratory]] and alimentary tracts, skin and later (1-5 wk. post infection) to the brain
 
*'''Clinical signs''':
 
**Mucopurulent oculonasal discharge
 
**Keratitis
 
**[[Lungs - inflammatory#Interstitial pneumonia|Interstitial pneumonia]]
 
**Severe clinical pneumonia follows secondary infection with [[Bordetella bronchiseptica and Bordetella avium|''Bordetella bronchiseptica'']]
 
**Smelly sometimes bloody diarrhoea
 
**Eruptions on the skin including hyperkeratosis of the nose and pads (hardpad)
 
**[[PNS Repsonses to Injury#Segmental Demyelination|Demyelination]] (especially in cerebellum) -> incoordination or muscle tremors -> paralysis and coma or convulsions -> death
 
**Encephalitis
 
**Secondary pyogenic infections associated with immunosuppression and damage to epithelia
 
**Recovered animals may have persistent or spasmodic chorea
 
**The severity of the disease may vary; if enough neutralising antibody develops in the early stages, the virus maybe kept restricted largely to the lymph nodes.
 
*'''Diagnosis''':
 
**May present as series of infections
 
**'''Immunocytochemistry''' of inclusion bodies
 
***Intracytoplasmic inclusions may be found in most affected tissues
 
***Inclusions persist longest in the brain (may be intranuclear) and the alveolar macrophages
 
***Sections of fixed bronchial tissue, lung, macrophages, bladder may be used or nasal or conjunctival epithelium from live animals
 
**Giant cells may be seen in the alveoli
 
*'''Control''':
 
**Live attenuated virus vaccines given at 10 and 12 weeks of age
 
***Some now given at 7 and 10 weeks to allow socialisation
 
**Homeopathic vaccines do not work
 
**Live attenuated vaccines may kill some wildlife therefore '''Iscom vaccine''' is used in seal sanctuaries
 
 
 
*Can contribute to [[Viral infections#In Dogs|Infectious canine tracheitis]]
 
*May be involved in [[Pancreas - inflammatory#Chronic interstitial pancreatitis|chronic interstitial pancreatitis]]
 
*May cause [[Bones - developmental#Retention of elongated primary trabeculae|growth retardation lattice]]
 
*May also trigger latent [[Tissue cyst-forming coccidia|Toxoplasmosis]] due to suppressing effect on lymphoid tissue
 
 
 
===Hendra Virus===
 
 
 
*Equine Paramyxovirus
 
*Causes [[Viral infections#Hendra virus|respiratory infections]] with respiratory distress and paralysis
 
*Potentially zoonotic (beware palpating inside the throat for obstruction)
 
 
 
 
 
===Nipah Virus===
 
 
 
*Infects pigs and humans
 
*Humans exposed to pig blood are at risk
 
 
 
 
 
 
 
 
 
 
 
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Latest revision as of 10:52, 22 May 2010