Exam III Review

Exam III Review - Lecture 16: Basic Concepts in Medical...

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Lecture 16: Basic Concepts in Medical Virology What are the three things that must occur in order for a virus to cause disease in humans? o 1. Non-specific surface defenses activated o 2. Immune system is lowered (?) o 3. Tissue cell death or destructive immune/inflammatory response There are 3 potential outcomes of a viral infection. What are they? o 1. Failed infection (abortive) o 2. Cell death (lytic) o 3. Replication without cell death (persistent) There are 4 types of persistent viral infections. Be able to distinguish/describe these 4 types. o 1. Chronic (nonlytic, productive) o 2. Latent (limited viral macromolecular but no virus synthesis) o 3. Recurrent o 4. Transforming (immortalizing) Many viruses have the means to escape one or more aspects of the immune system. Which strategies were mentioned in class? o Occur in an infected cell that is not killed by the virus: Some viruses can leave the cell without causing it to lyse (productive, nonlytic infection) Some viruses enter a resting stage (latency) after infection (non-productive, nonlytic infection) Replication triggered by various stimuli What factors affect the length of the incubation period for a virus?
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o Incubation period – virus is replicating but has not reached the target tissue, disease is not yet apparent Short: Site of infection is the target tissue Long: Site of infection is not the target tissue: o Virus must travel to other tissues o Viral load must be amplified o Symptoms are caused by immunopathology What factors determine viral disease severity? o Severity of symptoms depend upon target tissue function and immunopathologic response: o Inappearent infections: Infected tissue is undamaged Infection controlled before virus reaches target site Target tissue is expendable Damaged tissue is rapidly repaired Extent of damage does not interfere with function What determines the mode of viral transmission? o The source of the virus determines the mode of transmission: Direct contact (including sexual) Injection w/ contaminated fluids Organ transplantation Respiratory transmission Fecal-oral routes
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Viruses can be either enveloped or naked. How are the two types different from one another? o Enveloped: Comparatively fragile (to naked) Require intact envelope Respiratory transmission Blood Mucus Saliva Semen Injection Organ transplantation Sensitive to Acids Detergents o Naked (Non-Enveloped): Can withstand drying Detergents Extremes of pH and temperature Respiratory transmission Fecal-oral transmission Acquired from contaminated objects = Fomites
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Lecture 17: H1N1/Influenza Be able to describe the genome organization, virion structure and other identifying characteristics of the Influenza/H1N1 viruses. o
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This note was uploaded on 04/29/2010 for the course BIOL 1404 taught by Professor Machaeldini during the Fall '09 term at Texas Tech.

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Exam III Review - Lecture 16: Basic Concepts in Medical...

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