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45 Cards in this Set
- Front
- Back
What viruses cause respiratory infections and diseases?
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- Influenza virus
- Rhinovirus - Coronavirus - Parainfluenza Virus - Respiratory Syncytial Virus (RSV) - Metapneumovirus - Adenovirus (sometimes) |
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What causes influenza epidemics? Pandemics?
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- Epidemics - genetic drift (mutations)
- Pandemics - genetic shift (reassortment) |
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What cells are infected by influenza virus? How are these cells destroyed/damaged?
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- Ciliated epithelial cells lining upper resp. tract, trachea, and bronchi
- Virus replication and cytotoxic T lymphocytes damage and destroy respiratory epithelium |
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How long is the incubation period for influenza virus?
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Short ~24 hours
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What are the symptoms of influenza virus infection in adults?
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- Rapid onset of fever
- Malaise - Myalgia - Sore throat - Non-productive cough |
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What are the symptoms of influenza virus infection in children?
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- Similar to adults
- Higher fever - GI symptoms (abdominal pain and vomiting) - Otitis media - Myositis - Croup |
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What are the complications of influenza virus infection?
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- Primary viral pneumonia
- Secondary bacterial pneumonia - Myositis and cardiac involvement - Neurological syndromes: Guillain-Barré Syndrome, Encephalopathy, Encephalitis, Reye Syndrome |
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How do you diagnose influenza infection?
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- Rapid antigen capture (detects Nucleoprotein, NP, ~15 min.)
- RT-PCR |
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Where does influenza virus replicate cellularly? What kind of genome?
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- Replicates, transcribes in nucleus (unusual)
- (-) ssRNA |
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What kind of drugs are used to treat influenza infections?
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- Zanamivir and Oseltamivir (NA inhibitors)
- Previously Amantadine and Rimantadine (block M2 proteins - inhibits uncoating) - Ribavirin (inhibits viral RNA synthesis) |
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What kind of vaccines are used to prevent influenza infections?
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- Formalin inactivated (mix of prevalent antigenic types)
- Attenuated infectious viruses (intranasal and must be kept cold) |
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What is the cause of 50% of common colds? Type - genome?
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Rhinovirus (Picornavirus = +ssRNA icosahedral)
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What causes the symptoms of Rhinoviruses?
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Inflammatory response - infected cells in nose release bradykinin and histamine --> nasal discharge, sore throat, cough, headache
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What are the temperature considerations of Rhinovirus? Coronoviruses?
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- Rhinoviruses - grow better at 33 degrees than 37 degrees (sensitive to fever)
- Coronoviruses - grow better at 33 degrees to 35 degrees |
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What immune response is important for limiting re-infection of rhinoviruses?
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Secretory IgA
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How are Rhinoviruses transmitted between people?
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Directly from individual to individual via respiratory secretions (via fomites - door handle, silverware, etc)
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How do you treat / prevent Rhinoviruses?
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No effective prevention and control measures yet
(Experimental: IFN-α (induce antiviral resistance), soluble ICAM-1 (compete for attachment), viral protease inhibitors, WIN compounds (block uncoating by inserting in virus surface pore)) |
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What is the cause of 10-15% of common colds? Genome?
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Coronaviruses = +ssRNA (helical)
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What cells are affected by Coronaviruses? Symptoms?
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- Epithelial cells of upper respiratory tract
- Watery eyes, sneezing, nasal congestion, sore throat, sometimes fever, chills, headache, other aches, cough |
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What is the cause of SARS?
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- Coronavirus - +ssRNA helical
- Originated from virus in horseshoe bats in China |
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How was SARS (Coronavirus) spread?
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Face-to-face contact (virus in respiratory secretions and feces)
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How are Coronoviruses (common cold and SARS treated)?
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No vaccines available or efficacious therapies
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What diseases / viruses are caused by "Paramyxoviruses"? Way to remember? Genome?
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- Parainfluenza (croup)
- RSV (Respiratory Syncytial Virus) - Mumps and Measles PaRaMyxovirus - (-)ssRNA helical |
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What are the important surface proteins on Paramyxoviruses (Parainfluenza, RSV, Mumps, Measles)?
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- F = Fusion protein (for virus entry)
- HN = Hemagglutinin (viral attachment) and Neuraminidase (viral release) ** HN Not on RSV |
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How are Parainfluenza viruses (Paramyxoviradae) spread? When are they more common?
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- Respiratory secretions
- Fall and winter, common nosocomial infection (hospital acquired) |
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What cells are affected by a Parainfluenza infection (Paramyxoviradae)? Symptoms?
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- Infect epithelial cells in upper respiratory tract
- Lower respiratory complications in infants and young children, CROUP, subglottal swelling may close airway |
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What virus causes CROUP?
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Parainfluenza (Paramyxovirus)
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What are the types of Parainfluenza viruses? Differences?
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- Types 1, 2, 3 - resp. tract disease ranging from mild common colds to bronchiolitis an/or pneumonia
- Type 4 - usually mild |
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What protects from Parainfluenza infection?
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IgA (against HN - hemagglutinin/neuraminidase) in nasal secretions (short-lived protection)
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What patient population is affected more severely by Parainfluenza infections?
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Children w/ T cell deficiencies
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What is the most common cause of fatal acute respiratory tract infection in infants and young children?
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RSV (Respiratory Syncytial Virus) - type of Paramyxovirus
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How common is RSV (Respiratory Syncytial Virus) - type of Paramyxovirus?
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Infects virtually everyone by age 2; re-infections occur throughout life and can be sever in elderly
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Where does RSV (Respiratory Syncytial Virus) - type of Paramyxovirus infect? Symptoms?
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- Localized infection of respiratory tract
- No viremia or systemic spread - Pneumonia from cytopathologic spread of virus (syncytia), Bronchiolitis (by immune response), narrowing of airways (leads to obstruction) - Typical "giant cells" lead to airway obstruction |
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Can you be protected from RSV (Respiratory Syncytial Virus) - type of Paramyxovirus infection?
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- Maternal antibody does not protect infant (hence most common cause of fatal acute resp. tract infxn in infants and young children)
- Natural infection does not prevent re-infection |
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What type of immune response to RSV (Respiratory Syncytial Virus) - type of Paramyxovirus is mediated by adults? Infants?
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- Adults - Th1 response --> IFN-γ --> activates macrophages, NK cells, CMI and B cells
- Infants - Th2 response --> IgG4, IgG1, IgE and IL-4 lead to mast cell degranulation, IL-5 leads to eosinophilia and wheezing |
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What are the symptoms of RSV (Respiratory Syncytial Virus) - type of Paramyxovirus infection for children <1 yo, children, older children and adults?
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- <1 yo - fever, cough, dyspnea, cyanosis
- Children - febrile rhinitis and pharyngitis - Older children and adults - common cold |
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How do you treat healthy infants, premature or immunocompromised infants, and premature infants with RSV (Respiratory Syncytial Virus) - type of Paramyxovirus?
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- Healthy infant - supportive tx, oxygen, IV fluids, nebulized cold stream
- Premie or Immunocompromised - aerosolized ribavirin - Premie - passive immunization w/ anti-RSV Ig and humanized monoclonal Abs * NO vaccine * |
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What are the symptoms and treatments for Metapneumovirus (Paramyxovirus)?
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- Acute respiratory illness similar to RSV (most severe cases seen in infants, elderly, and immunocompromised)
- Upper RTI - common cold, bronchitis, wheezing, pneumonia - No vaccine or antiviral therapies - Most children infected by 5 yo |
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What are the two emerging respiratory viruses with high mortality rates?
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Hendra and Nipah virus - Paramyxoviruses (jumped from bats to people)
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What kind of viruses are Adenoviruses? Symptoms?
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- DS linear DNA virus
- Respiratory infection (pharyngitis), conjunctivitis (pink eye), GI infections, hemorrhagic cystitis (inflam. of urinary bladder) - Resp. infections --> systemic infections (viremia) in immunocompromised |
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What can happen to the respiratory tract when infected with Adenovirus?
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- Destructive productive infection
- Persistent infection w/ virus shedding - Latent infections in lymphoid tissues like tonsils or adenoid tissue |
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What populations of patients are Adenovirus infections associated with?
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- Military recruits - acute respiratory disease
- Children / bone marrow transplant recipients - acute hemorrhagic cystitis |
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How are Adenoviruses spread?
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- Aerosol, close contact, or fecal-oral
- Fingers spread virus to eyes (conjunctivitis) |
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What types of cells are affected by Adenoviruses?
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- Mucoepithelial cells in respiratory tract, GI tract, conjunctiva or cornea
- Persists in lymphoid tissue (e.g., tonsils, adenoids, Peyer patches) |
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What immune responses are important for Adenoviruses?
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- Antibody is important for prophylaxis and resolution
- Cell-mediated immunity also important |