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31 Cards in this Set
- Front
- Back
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Kind of virus orthomyxovirus is?
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Enveloped, SS RNA, linear, helical, segmented.
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Where does orthomyxovirus replicate?
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NUCLEUS (not cytoplasm)
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Lifecycle?
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(HA) Hemagglutinin – attaches to ‘NANA’ groups on host cell for FUSION
- Anchored in virus lipid bilayer - Upon CLEAVAGE → viral envelope fuses with host endosome |
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Name 4 key pathogenic characteristics of the flu?
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NA (Neuraminidase)
MP1 (Matrix Protein) RNP (RiboNucleoprotein) Lipid Bilayer / Lipoprotein envelope NEGATIVE singel strand RNA |
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Why is each of them good:
NA: |
Neuraminidase is an ezyme that facilitates budding
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Why is each of them good:
MP1: |
Matrix protein is the inner surface of the envelope.
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Why is each of them good:
RNP: |
associates with and stabilizes RNA
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Why is each of them good:
lipid bilayer / lipoprotein envelope: |
Causes easy drying, short half life.
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Why is each of them good:
- SS RNA: |
8 segments all needed for full function, each has its own job.
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Process of viral replication?
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HA attaches to host cell NANA (fusion, endocytosis). MP1 releases RNP (uncoating of the endosome). RNP heads to nucleus, + RNA copy is produced, as are proteins. Then HA, NA, MP1 go to membrane (RNP goes instead to nucleus to associate with RNA and then to membrane). NA facilitates progeny budding from surface, and host cell dies from trauma to membrane surface.
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Why do pandemics happen every 10 to 15 years?
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Antigenic sudden shift. Major change in antigenic type, 2 virusses mix and repackage/reassort RNA segments.
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What is drift?
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Minor changes in HA/NA via point mutation, local outbreaks.
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Influenza A:
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Avian, mammals. Pandemics (such as the H5N1 Avian flu), H1N1, HA - major and minor changes, NA some variation, epidemics.
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Tx for Influenza A?
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Zanam/Oseltam; Aman/Riman
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Influenza B:
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Humans. Mild, HA drive only (local outbreak).
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Tx for Influenza B?
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Zanam/Oseltam.
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Influenza C:
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Humans. Mild, uncommon.
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Tx for Influenza C?
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Zanam/Oseltam.
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Epidemiology of the flu
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Significantly changes national mortality rates, antigenic shift causes pandemics, drift causes local outbreaks. Antigenic recycling (older population = resistance?). types & strains vary each year (need new vaccine). Short incubation period (2 days), RAPID spread, associated with groups and facilities. Happens November through March.
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Pathogenesis of the flu
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Multiplies in respiratory epithelium, max titers in 2 days. Emesis, edema --> necrosis and leukocyte infiltration. Sudden onset: myalfia, H/A, fever, chills. Congestion, sore throat, cough, rhinorhea, SOB. --> may progress to pneumonia.
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Managing the flu
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ASA (but not kids). Codeine, rest, NO AB. Antivirals: Zanamivir, Oseltamivir. NA inhibitors = virus cannot bud away from infected cell. Amantidine, Rimantidine: blocks uncoating of viral RNA, increases resistance in 2005. A MAN TO DINE takes off his coat.
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Complications of the flu
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Pneumonia, myocarditis, bacterial pneumonia. Influenza paves the way, by destroying the integrity of the respiratory mucosa/ mucociliary clearance mechanism. Depresses cell-mediated immunity, macrophage function, phagocyte function. You can get Reye's Syndrome.
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Prevention of the flu
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Vaccines (70% effective). Give before flu enters community.
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What's the TIV like?
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Inactivated trivalent influenza vaccine (TIV). 2 strains type A, 1 strain type B. CI: anaphylactic egg allergy, current fever, GBS (Guillán Barré hx with 6wks previous vacc.). SE: site sore, low grade fever. Maybe.
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What's the LAIV like?
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LIve Attenuated Influenza Vaccine
healthy people ages 2-49 take it. CI: egg allergy, outside age range, chronic illness, contact with immunocompromise. SE: runny nose, nasal congestion, HA, sore throat. |
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Priority vaccine groups (high risk groups):
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Peds: 6 months to 5 yrs.
Adults 50-65 yrs. Healthcare workers, essential occupations (police, fire, EMS). Women who anticipate pregnancy during flu season General population (it's cost effective!) |
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Why would you use zanamivir, osetalmivir, amantidine, or rimantidine as prophylaxis?
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Buys time for late immunization (outbreaks for high risk unimmunized pts).
60-90% effective against sensitive strains. |
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H1N1 SWINE FLU epidemiology
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Mexico 3/09, US 4/09, increased activity fall of 2009, younger ages.
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H1N1 SWINE FLU Clinically
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like seasonal flu, but worse in younger pts.
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H1N1 SWINE FLU Prevention
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Hygiene, vaccine (preggers, health care workers, infant contacts, 6 months to 4 yrs., 5-18 yrs with medical condition, 25-64 with medical conditions, then general populations)
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H1N1 SWINE FLU Treatment
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Antivirals within 2-3 days. Tamiflu = Oseltamivir. Relenza = Zanamivir.
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