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Micro 12/07/12 RNA Respiratory Viruses
HDPP final at UMMSM
56
Microbiology
Graduate
12/12/2012

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Cards

Term
What picornavirus causes the common cold and upper respiratory infections?
Definition
Rhinovirus
Term
Is there a vaccine for rhinovirus?
Definition
No--there are over 100 serotypes and infection is self-limited
Term
What does rhinovirus bind to?
Definition
ICAM-1
Term
What is the surface structure of rhinovirus?
Definition
The surface has a common pocket antigen and a variable knob antigen
Term
Why is rhinovirus seasonal?
Definition
Its optimal temperature is 33*C
Term
How is rhinovirus spread?
Definition
By direct contact from hands and fomites or by inhalation of droplets
Term
What viruses are in the orthomyxovirus family?
Definition
Influenzas A, B, and C
Term
What is each influenza important in?
Definition
Influenza A is important in pandemics, influenza B is important in local epidemics, influenza C is not very common
Term
What forms the influenza envelope?
Definition
Neuraminidase and hemagglutinin, which forms clusters of cells
Term
How is the influenza genome set up and what is special about it?
Definition
The -RNA is helical and has 8 segments, and it carries its own RNA polymerase. Unlike other RNA viruses, it enters the nucleus to steal a cap for the RNA
Term
What is antigenic drift?
Definition
Simple mutation of NA or HA sites, but antibodies can still recognize the virus
Term
What is antigenic shift?
Definition
Simultaneous infection of different orthomyxoviruses results in reassortment, leading to a new antigen
Term
How many HA subtypes are there? NA?
Definition
15 HA and 9 NA
Term
How do highly infective, pandemic flu strains arise?
Definition
Segmental recombination of a successful avian (swine, etc.) influenza that underwent drift with a human influenza is reassortment that leads to viruses infective to multiple species
Term
What causes the flu symptoms?
Definition
The body's response of IFN induction, cell-mediated immunity, and desquamation of mucous secreting respiratory cells
Term
What is Reye's syndrome?
Definition
A neurological complication of influenza, characterized by acute encephalopathy along with fatty degeneration of the liver. Mortality is up to 40%
Term
What is Guillian-Barre syndrome?
Definition
An autoimmune reaction to the flu leading to muscle weakness or self-resolving paralysis secondary to viral affliction of the peripheral nervous system
Term
How do antivirals affect influenza?
Definition
Amantadine and zanamivir inhibit replication or block neruaminidase
Term
What is the best control for influenza?
Definition
Annual vaccines
Term
What is the immune response to a second influenza exposure?
Definition
If the virus is a variant (as it likely is), the individual will only make antibody to previously experienced epitopes, not to the new epitopes
Term
Why do antibiotics not affect the flu?
Definition
They would only work on pneumonia caused by a secondary bacterial infection, which is extremely rare
Term
What do coronaviruses look like?
Definition
They are medium-sized enveloped virions that look like crowns under a microscope
Term
How is the genome of coronavirus set up?
Definition
It is +RNA and is translated in phases, assembled at the RER
Term
How do coronaviruses present?
Definition
Typically as the common cold, but can also cause GI disease
Term
What are the rare complications of coronavirus?
Definition
Viral pneumonia, myocarditis, and SARS
Term
Where does coronavirus cause infection?
Definition
It infects the epithelium of the upper respiratory tract, where it is restricted because it survives best at 33-35*C
Term
What protection does the coronavirus have?
Definition
The envelope allows it the possibility of surviving the GI tract, and it is not destroyed by serum antibodies
Term
What is the structure of paramyxoviruses?
Definition
Helical nucleocapsid with -RNA and HA/NA envelope
Term
What are the primary diseases of parainfluenza?
Definition
Croup, pneumonia, and bronchitis
Term
Who is at highest risk for parainfluenza 1/2 and what time of year?
Definition
Children under 5; autumn
Term
What are the symptoms of parainfluenza based on?
Definition
Symptoms are based on where in the URT the virus replicates (larynx through lungs)
Laryngitis: croup, hoarseness, barking cough
Bronchiolotis: cough, dyspnea, etc.
Term
How many serotypes does parainfluenza have?
Definition
4
Term
How many serotypes are there for mumps?
Definition
1
Term
What does mumps cause?
Definition
Severe parotitis and rarely, meningitis
Term
How is mumps transmitted?
Definition
Via respiratory droplets only in humans. It has an 18 day incubation period
Term
How does mumps virus replicate?
Definition
In the URT before disseminating to other sites, mainly the parotid glands, which become enlarged
Term
What are possible sequelae of mumps?
Definition
Orchitis, pancreatitis, and meningoencephalitis
Term
What comprises the envelope of measles virus?
Definition
HA, but not NA
Term
What is the pathology of measles?
Definition
Rash and rarely encephalitis
Term
How is measles transmitted?
Definition
It is highly infectious and affects the respiratory tract in humans only. Incubation is usually 9 days, and symptoms last about a week
Term
How does measles virus spread in the body?
Definition
It spreads from the URT through blood and lymph to endothelial cells and T-cells
Term
What are key symptoms of measles?
Definition
Maculopapular rash, high fever, conjunctivitis, coryza, and cough followed by lifelong immunity. The rash starts discrete but becomes confluent and spreads rapidly. Koplik's spots are present
Term
What are Koplik's spots?
Definition
Clustered, white ulcerative lesions on the buccal mucosa
Term
What is subacute sclerosing panencephalitis?
Definition
Caused by CNS infection with defective measles virus. It is characterized by behavioral changes, myoclonic jerks, and blindness.
Term
What are complications of subacute sclerosing panencephalitis?
Definition
If cell-mediated immunity is defective, viral replication can continue and cause death
Term
What is respiratory syncytial virus?
Definition
A pneumovirus that does not disseminate from the URT. The virion is large but not resistant to desiccation and is spread by large-droplet aerosols
Term
What is the cause of the symptoms in RSV?
Definition
Pneumonia is due to viral cytopathic effects; bronchiolitis is mediated by host immunity
Term
What happens to children or adults who contract RSV?
Definition
Infants are hospitalized with fever, cough, dyspnea, and cyanosis.
Young kids get febrile rhinitis.
Adults just get cold symptoms
Term
How is RSV resolved?
Definition
Humanized IgA or antiviral ribavirin must be given because maternal IgG cannot protect infants, natural infection does not confer immunity, and there is no vaccine
Term
What is the single most important cause of severe respiratory illness in small children?
Definition
Respiratory syncytial virus
Term
What family contains rubella virus?
Definition
Togavirus
Term
What is the structure of rubella virus?
Definition
Enveloped +RNA virion
Term
What is the action of rubella virus?
Definition
It disseminates from the pharynx, causing fever, rash, and long-lasting lymphadenopathy
Term
How does the rash caused by rubella present?
Definition
It is a red, maculopapular rash that spreads from the upper body to the lower body
Term
How does rubella affect a fetus?
Definition
Rubella virus spread through the blood and across the placenta can be stopped by antibodies. Congenital infection can lead to cataracts, heart defects, deafness, intrauterine growth retardation, or microcephaly. In general, growth retardation results in failure to thrive and death within a year
Term
What is the MMR vaccine?
Definition
Measles, mumps, and rubella vaccine contains live, attenuated viruses of single serotypes. Vaccination at 15 mo, 4-6 years, and before junior high. 95% develop lifelong immunity with a single dose
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