Orthomyxoviridae, Paramyxoviridae

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mstengs
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172876
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Orthomyxoviridae, Paramyxoviridae
Updated:
2012-09-23 21:33:11
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Viruses
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  1. Orthomyxoviridae

    - Disease
    - Virion Structure
    - Influenza virus

    • (-) RNA, segmented (8); helical; enveloped
    • *Replicate in nucleus
  2. Orthomyxoviridae

    Influenza A:
    Influenza B:
    Influenza C:
    • A - Humans & other mammals; cause human disease
    • B - Humans only; cause human disease
    • C - Humans only
  3. Hemagglutinin protein (HA)
    • - Surface spike on orthomyxovirus envelope, anchored by M protein
    • - Binds to sialic receptors on cell membranes of upper resiratory tract, allowing adsorption to host cell memebrane
    • - Cleaved into HA1 & HA2 --> infectivity

    • - Major antigen
    • - Subject to antibodies
  4. Neuraminidase protein (NA)
    • - Surface spike on orthomyxovirus envelope, anchored by M protein
    • - Cleaves neuraminic acid in the mucin that covers and protects upper respiratory epithelial cells, allowing Hemagglutinin to adsorb to the cell membranes
    • - Cleaves sialic acid receptor to allow release of virions from cell
    • - Prevents mature virus from aggregating within infected cell

    • - Major antigen
    • - Subject to neuraminidase inhibitors
  5. Antigenic Drift
    • - Point mutation changes in antigenic nature of HA or NA glycoproteins
    • - Results in new strains that result in recurrent epidemics of influenza
    • - Requires continual development of new vaccines

    • - Most pronounced in Influenza A
    • - Occurs in HA & NA
    • - HA drift is more clinically significant
  6. Antigenic Shift
    • - Major change in HA, NA, or both
    • - Reults in new virus that results in pandemic of influenza
    • - Genetic ressortment of avian and animal viruses

    - Only occurs in Influenza A
  7. Influenza Transmission
    • - Small-particle aerosol
    • - Person-to-person
    • - Eyes, Mouth
    • - Esp. children
    • - Esp. December-May
  8. Clinical Manifestations of Influenza
    • - Fever, headache, chills, myalgia, malaise
    • - Dry, explosive cough cough
    • - Tracheobronchitis (upper respiratory)
  9. Complications of Influenza
    • - Primary viral pneumonia (severe infection pt's)
    • - Secondary bacterial pneumonia (immunocompromised pt's)
  10. Croup
    • - In children (3-5 mo.)
    • - Characterisitic "seal-like barking" cough

    - Airway swelling and narrowing secondary to upper respiratory infection (esp. parainfluenza virus, influenza virus)
  11. Reye's Syndrome
    • - Severe liver and brain disease
    • - Children < 4yrs
    • - Mortality 10-40%
    • - Caused by aspirin administration to children with viral infection (esp. influenza B)


    • *Never give aspirin to children for fever!
    • - Give acetaminophene for antipyretic
  12. Amantadine
    • - Antiviral Drug against Influenza A
    • - Targets M2 protein and prevents viral uncoating inside host cell
  13. Rimantadine
    • - Antiviral Drug against Influenza A
    • - Targets M2 protein and prevents viral uncoating inside host cell
  14. Neurominidase inhibitors
    (Tamiflu)
    • - Antiviral drug against Influenza
    • - Prevents viral assembly and release from host cell
  15. Influenza Vaccination
    • - Inactivated
    • - Prevents Influenza A & b
    • - Contraindicated if severe egg allergy
    • - Recommended for elderly, children, pregnant women, chronically ill (e.g. asthmatics), healthcare workers
  16. Flu-Mist
    • - Attenuated vaccination against influenza
    • - Recommended for healthy 5-29 yrs
  17. H5N1 - Avian Flu

    - Resistance
    - Treatment

    - Transmission
    - Mortality
    • - Strains resistant to Amantadine/Rimantadine
    • - Sensitive to Neuraminidase inhibitors

    • - Direct transmission from birds
    • - 59% mortality rate
  18. H1N1 - Swine Flu

    - Genetic recombination
    - Mortality
    -
    • - Two pig genes, one avian gene, one human gene
    • - Not more lethal than seasonal flu
    • - More pathogenic to young, healthy adults
  19. Paramyxoviridae

    - Disease
    - Virion Structure
    • - Parainfluenza Virus
    • - Respiratory Syncytial Virus (RSV)
    • - Human Metapneumovirus (HMPV)
    • - Measles
    • - Mumps
    • - Hendra Virus
    • - Nipha Virus

    • (-) RNA, non-segmented; Helical; Enveloped
    • Replication in cytoplasm

    • *HA and NA proteins are the in same glycoprotein spike
    • *Fusion (F) protein causes fusion of infected host cells into syncytial cells
  20. Clinical Manifestations of Parainfluenza
    • - Adults: upper respiratory infection
    • - Children: lower respiratory infection (+ croup) (+ pneumonia/bronchitis in infants)
  21. Parainfluenza Transmission
    • - Large droplets
    • - Bodily secretions
  22. Vaccine Against Parainfluenza
    None
  23. Respiratory Syncytial Virus (RSV)

    - Epidemiology
    - Clinical Manifestations
    #1 cause of pneumonia/bronchiolitis in infants/children

    • - Adults: upper respiratory infection
    • - Children: lower respiratory infection
    • - Reinfection is the rule: usually upper respiratory
  24. Transmission of RSV
    • - Large droplets
    • - Person-to-person
    • - Contact of surfaces
  25. RSV Route of Entry
    • Eye & Nose
    • (not so much mouth)
  26. Complications of RSV
    • - Chronic pulmonary disease (e.g. asthma)
    • - Increased risk of mortality for pt's with lung/cardiac/congenital anomalies
  27. Vaccine Against RSV
    None

    *Breastfeeding may confer IgA antibodies that can reduce severity of RSV infection
  28. Clinical Manifestations of Human Metapneumovirus (HMPV)
    • - Rhinorrhea, cough, wheezing, rales
    • - Bronchitis, Bronchiolotis, Pneumonia, Pharyngitis, Asthma exacerbation
  29. Hendra Virus

    - Taxonomy
    - Natural Host Animal

    - Clinical Manifestations
    • - Emerging Paramyxovirus
    • - Natural Host: Fruit bats
    • - Infected horses in Australia

    • - Severe respiratory symptoms w/ systemic symptoms
    • - High mortality
  30. Nipha Virus

    - Taxonomy
    - Natural Host Animal

    - Clinical Manifestations
    • - Emerging Paramyxovirus
    • - Natural Host: Fruit bats
    • - Infected pigs in Malaysia

    • -Predominantly encephalitic symptoms (rather than respiratory)
    • - High mortality

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