Final Exam - Paramyxoviridae Flashcards
Paramyxoviridae
Causes rinderpest, canine distemper virus, Newcastle disease virus, Nipah, measles and mumps. Impact has been reduced from vaccination.
Two genera that come from Paramyxoviridae are:
- Avulavirus
2. Morbilivirus
3 membrane proteins
- Unglycosylated matrix protein (M)
- Fusion protein (F) glycosylate envelope protein
- Hemagglutinin (H) glycosylated envelope protein
3 nucleocapsid proteins
- RNA binding protein (N)
- Phosphoprotein (P)
- Large polymerase (L)
Antibodies directed against these proteins
Usually neutralizing antibodies - important in protection against paramyxovirus infection
Replication - Rubulaviruses, Respiroviruses and Avulaviruses
The HN molecule binds to sialic acid residue - either glycolipids or glycoproteins.
Replication - Morbiliviruses
The receptor is located on lymphocytes, dendritic cells or macrophages - CD150
Replication - Henipaviruses
The receptor is ephrin B2 and B3 cell surface proteins on endothelial cells or on brain stem neurons
Replication - Pneumoviruses
The receptor is heparan sulfate.
Paramyoviruses Inclusion Bodies
Cytoplasmic acidophilic inclusion bodies, composed of ribonucleoprotein structure
Newcastle Disease
A disease of chickens. 10 serotypes. Avian ParaMyxoViruses. APMV-1 to APMV-10. NDV = APMV-1.
Newcastle Disease - 5 Pathotypes
- Viscerotropic velogenic
- Neurotropic velogenic
- Mesogenic
- Lentogenic (respiratory)
- Asymptomatic
Newcastle Disease Hosts
Chickens are highly susceptible to disease. Turkeys do NOT develop severe signs.
Newcastle Disease Transmission
Direct contact with secretions of infected birds via ingestion and inhalation. Fomites feed, water, premises, human clothing, boots, sacks, egg trays/crates. Hatching chicks may be infected through the egg for some NDV strains.
Newcastle Disease Occurence
Velogenic NDV is endemic in areas of Mexico, Central and South America. In double crested wild cormorants in the US and Canada. Lentogenic strains of NDV are worldwide in their distribution.
Newcastle Disease Diagnosis
Clinical signs are rare. Clinical signs alone do not present a reliable basis for diagnosis of ND.
Lentogenic Strains
Usually associated with subclinical disease marked by mild respiratory symptoms; coughing, gasping, sneezing and rales. Morality is negligible.
Velogenic Strains
Cause severe disease in chickens with high mortality for unvaccinated chickens. Signs, principally respiratory and/or nervous. Initial clinical signs vary but include: lethargy, inappetence, ruffled feathers, edema. Greenish or white water diarrhea, dyspnoea and inflammation of the head and neck with cyanotic discoloration. Often result in death with few or no signs.
Velogenic Strains - Neurological Signs
May be manifested as tremors, tonic/clonic spasms, wing/leg paresis or paralysis, torticollis, and aberrant circling behavior.
Velogenic Strains - Lesions
Only velogenic strains produce significant gross lesions such as: swelling of periorbital area of entire head. Edema of interstitial or peritracheal tissues of neck. Edema, hemorrhages or degeneration of ovaries. Edema, hemorrhages, necrosis of ulceration of respiratory/digestive lymphoid tissue.
Laboratory Diagnosis
Samples collected from recently dead or moribund birds. Sent to a reference laboratory. Dead birds: oronasal swabs. Live birds: tracheal or oropharyngeal and cloacal swabs. Clotted blood samples or serum for serology. inoculation of embryonated specified pathogen free (SPF) eggs and tested for hemagglutination (HA) activity. ELISA. and Validated xisspecific molecular methods (PCR)
Prevention and Control - Medical Prophyla
Vaccination with live vaccines: lentogenic vaccines and mesogenic vaccines. Live virus vaccines administered by incorporation in the drinking water, as a coarse spray (aerosol), or by intranasal or conjunctival instillation.
Newcastle Disease Vaccinations
Inactivated vaccines and new recombinants vaccines (fowlpox virus, vaccinia virus, pigeonpox virus, turkey herpesvirus and avian cells in whicht eh HN gene, the F gene or both, of NDV are expressed)
Sanitary Prophylaxis
NO TREATMENT! One age group per farm (“all in-all out) breeding is recommended.
Nipah Virus
A newly emerging zoonosis that causes severe disease in both animals and humans. Causes encephalitis and respiratory illness.
Nipah Virus SYNONYMS in pigs
Barking pig syndrome, porcine respiratory and encephalitis syndrome, porcine respiratory and neurologic syndrome.
Nipah Virus - Agent
Genus Henipavirus. Rapidly progressive encephalitis in humans. High mortality rate. Severe, respiratory disease in pigs.
Nipah Virus - Transmission (Reservoir)
Flying foxes (fruit bats). Virus found in urine and maybe saliva from partially eaten fruit.
Nipah Virus - Clinical signs - Suckling pigs and piglets (
Labored breathing and muscle tremors with limb weakness. Mortality in piglets can be high.
Nipah Virus - Clinical signs - Young swine (1 to 6 months old)
Acute fever with respiratory signs. Labored breathing, nasal discharge and loud non-productive cough (“barking pig syndrome” or “one-mile cough”). Neurological signs. High morbidity and low mortality .
Nipah Virus Clinical signs - Older animals ( > 6 months old)
Acute febrile, with marked neurological signs. respiratory signs: open mouthed breathing, nasal discharge and sialorrhea (possibly due to pharyngeal paralysis). Morbidity in confined animals is ~100%. First trimester abortions may occur.
Nipah Virus - REMEMBER
Classified as a BSL4 agent!
Nipah Virus - Identification of agent
Virus isolation and characterization. Virus neutralization. RT-PCR. Immunohistochemistry.
Nipah Virus Prevention and Control - Sanitary prophylaxis
Strict biosecurity of swine installations to avoid contact with fruit bats and their secretions. Culling of seropositive swine.
Nipah Virus Prevention and Control - Medical prophylaxis
No vaccine yet!
Nipah as a biological weapon
Potentially high morbidity and mortality. Aerosolization potential.
Canine Distemper Virus
Belongs to Mobilivirus genus. Highly contagious, acute febrile disease of dogs. Currently a rare disease in dogs in the developed world.
Canine Distemper Virus - Host
Canidae (dogs, dingo, fox, coyotes), Procyonidae (raccoon, panda), Mustelidae (ferrets, mink, skunk) and Felidae (lions, tigers, leopards, cheetah).
Canine Distemper Virus - Clinical Features - Mild
At least 50% of infections are subclinical or mild. Inappetence, fever, respiratory tract infection such as bilateral nasal discharges, serous or mucopurulent, coughing, labored breathing.
Canine Distemper Virus - Clinical Features - Severe
Fever, followed by systemic spread of virus, anorexia, inflammation of the upper respiratory tract (serous or mucopurulent nasal discharges), conjunctivitis, depression, leukopenia. Some GI signs such as vomiting and watery diarrhea.
Canine Distemper Virus - Clinical Features - in puppies
Develop pneumonia, enteritis, conjunctivitis, rhinitis, and tracheitis. Secondary bacterial infections lead to bronchopneumonia.
Canine Distemper Virus - Clinical Features - Other signs
Develop CNS such as seizures, paraparesis or tetraparesis. Hyperkeratosis of footpads and nose.
Canine Distemper Virus - Pathogenesis
Replicates in the upper respiratory tract macrophages. Spreads to tonsils and lymph nodes. Virus infects all cells expressing CD150. The virus enters the blood stream and infects T and B cells.
Canine Distemper Virus - Diagnosis
Virus isolation. Immunofluorescence test. RT-PCR
Canine Distemper Virus - Control
Vaccination only in Canidae. Modified live vaccine available. Vaccinate puppies only after maternal antibody level has gone down. Hyperimmune serum administered immediately after exposure to the virus may help protect against infection.
