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15 Cards in this Set
- Front
- Back
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3 Strains of Flu
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A: Infects all animals
B: Humans C: Humans and Pigs |
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Spanish Flu
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- similar to H1N1
- very virulent - caused viscous pneumonia and inflammation of lower lungs (fluid --> suffocation) |
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2 Types of Viral Proteins
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1. Hemaglutinin: helps virus attach to cell surface, fusion with envelop to host cell plasma membrane, bind and enter
2. Neuraminidase: cleaves sialic acid; helps virus penetrate mucous to infect epithelial cells - important for escape, cleave to release virus |
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Course of Infection
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01: Droplet Inhalation
02: Replication in respiratory tract 03: Death of cells in respiratory tract (due to TGF Beta, transforming growth factor --> cytokine storm) 04: Influenza Syndrome |
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Pathogenesis
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01: Virus induces synthesis of TGF B inside respiratory cells
02: TGF B diffuses from cell and activates monocytes to make other cytokines 03: Multiple cytokines induce massive inflammation in respiratory tract Monocyte --> More TGF , TNF (tumor necrosis factor) , IL-1 |
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Rapid Diagnosis of Flu Infection
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- Test for AB:
01: Drop of serum is added; fluid moves by capillary action 02: T-test line H1N1 viral proteins attached 03: C-control line has H1N1 viral proteins attached 04: Anti-human AB coupled to purple dye is added --> Anti-human AB and serum will bind if positive: purple dye is concentrated on T line if serum has AB to H1N1 virus |
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Complications of Influenza
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- Pneumonia
- Bacterial pneumonia - Myositis (muscle inflammation) - Cardiac involvement - Reye's Syndrome: acute encephalitis in kids, risk incr by aspirin |
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Tamiflu
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- inhibits NA
- shortens duration of disease - Prophylaxis: prevents infection |
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Flu Vaccine
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- Mixture of extracts or purified HA and NA proteins from 3 dif strains of virus
- Virus prepared from virus grown in embryonated eggs, then chemically inactivated - Ideally vaccine incorporates Ags of the A and B strains that will be prevalent in the coming winter |
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Vaccine Recommended for:
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- Persons older than 50
- Healthcare workers - Preggers (2-3 tri) - Kids (5-18) |
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Mechs of Flu Variation
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- Ag Drift
- Ag Shift |
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Ag Drift
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MUTATION
if one of RNAs mutates --> dif HA if 2 RNAs mutate --> even more diverse; AB cannot recognize |
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Ag Shift
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REASSORTMENT
if infect same cell, can exchange genetic segments |
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Evolution of Flu Virus
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Usually humans can't be infected by avian flu
Pigs (swine :[ ) can be affected by both human and avian strains Pigs = mixing vessel for reassortment --> Their cells contain receptors recognized by human and avian viruses |
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Avian Flu
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- Found in wild birds' intestines
- Contagious - Asymptomatic - Also in domestic birds - Catch by direct contact, contaminated feed and H2O, and contaminated surfaces - Case in Hong Kong: little boy w/ sore throat and stomach ache --> dies one week later with total organ failure - Found large amts of H5 in stomach - Killed all chicken with high amts of H5 |
