Final Exam - Paramyxoviridae Flashcards Preview

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Flashcards in Final Exam - Paramyxoviridae Deck (45):
1

Paramyxoviridae

Causes rinderpest, canine distemper virus, Newcastle disease virus, Nipah, measles and mumps. Impact has been reduced from vaccination.

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Two genera that come from Paramyxoviridae are:

1. Avulavirus
2. Morbilivirus

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3 membrane proteins

1. Unglycosylated matrix protein (M)
2. Fusion protein (F) glycosylate envelope protein
3. Hemagglutinin (H) glycosylated envelope protein

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3 nucleocapsid proteins

1. RNA binding protein (N)
2. Phosphoprotein (P)
3. Large polymerase (L)

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Antibodies directed against these proteins

Usually neutralizing antibodies - important in protection against paramyxovirus infection

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Replication - Rubulaviruses, Respiroviruses and Avulaviruses

The HN molecule binds to sialic acid residue - either glycolipids or glycoproteins.

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Replication - Morbiliviruses

The receptor is located on lymphocytes, dendritic cells or macrophages - CD150

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Replication - Henipaviruses

The receptor is ephrin B2 and B3 cell surface proteins on endothelial cells or on brain stem neurons

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Replication - Pneumoviruses

The receptor is heparan sulfate.

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Paramyoviruses Inclusion Bodies

Cytoplasmic acidophilic inclusion bodies, composed of ribonucleoprotein structure

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Newcastle Disease

A disease of chickens. 10 serotypes. Avian ParaMyxoViruses. APMV-1 to APMV-10. NDV = APMV-1.

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Newcastle Disease - 5 Pathotypes

1. Viscerotropic velogenic
2. Neurotropic velogenic
3. Mesogenic
4. Lentogenic (respiratory)
5. Asymptomatic

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Newcastle Disease Hosts

Chickens are highly susceptible to disease. Turkeys do NOT develop severe signs.

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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.

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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.

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Newcastle Disease Diagnosis

Clinical signs are rare. Clinical signs alone do not present a reliable basis for diagnosis of ND.

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Lentogenic Strains

Usually associated with subclinical disease marked by mild respiratory symptoms; coughing, gasping, sneezing and rales. Morality is negligible.

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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.

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Velogenic Strains - Neurological Signs

May be manifested as tremors, tonic/clonic spasms, wing/leg paresis or paralysis, torticollis, and aberrant circling behavior.

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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.

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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)

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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.

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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)

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Sanitary Prophylaxis

NO TREATMENT! One age group per farm ("all in-all out) breeding is recommended.

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Nipah Virus

A newly emerging zoonosis that causes severe disease in both animals and humans. Causes encephalitis and respiratory illness.

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Nipah Virus SYNONYMS in pigs

Barking pig syndrome, porcine respiratory and encephalitis syndrome, porcine respiratory and neurologic syndrome.

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Nipah Virus - Agent

Genus Henipavirus. Rapidly progressive encephalitis in humans. High mortality rate. Severe, respiratory disease in pigs.

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Nipah Virus - Transmission (Reservoir)

Flying foxes (fruit bats). Virus found in urine and maybe saliva from partially eaten fruit.

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Nipah Virus - Clinical signs - Suckling pigs and piglets (

Labored breathing and muscle tremors with limb weakness. Mortality in piglets can be high.

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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 .

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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.

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Nipah Virus - REMEMBER

Classified as a BSL4 agent!

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Nipah Virus - Identification of agent

Virus isolation and characterization. Virus neutralization. RT-PCR. Immunohistochemistry.

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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.

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Nipah Virus Prevention and Control - Medical prophylaxis

No vaccine yet!

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Nipah as a biological weapon

Potentially high morbidity and mortality. Aerosolization potential.

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Canine Distemper Virus

Belongs to Mobilivirus genus. Highly contagious, acute febrile disease of dogs. Currently a rare disease in dogs in the developed world.

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Canine Distemper Virus - Host

Canidae (dogs, dingo, fox, coyotes), Procyonidae (raccoon, panda), Mustelidae (ferrets, mink, skunk) and Felidae (lions, tigers, leopards, cheetah).

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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.

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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.

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Canine Distemper Virus - Clinical Features - in puppies

Develop pneumonia, enteritis, conjunctivitis, rhinitis, and tracheitis. Secondary bacterial infections lead to bronchopneumonia.

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Canine Distemper Virus - Clinical Features - Other signs

Develop CNS such as seizures, paraparesis or tetraparesis. Hyperkeratosis of footpads and nose.

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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.

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Canine Distemper Virus - Diagnosis

Virus isolation. Immunofluorescence test. RT-PCR

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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.