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2.2: Brief descriptions of Microbial Pathogens

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  • Acellular pathogens: prions and viruses

    1. Prions: “proteinaceous infectious particles” (see fig. 18.6/18.7 p 475 in Belk’s Biology)

    -abnormally folded cellular proteins ( abbreviated “PrP’s”=Prion Proteins)

    -cause Transmissible Spongiform Encephalopathies or TSE’s

    -100% fatal

    -prion diseases in animals (examples):

    -scrapie/sheep, goats

    -CWD, Chronic Wasting Disease / deer, elk;

    -BSE, Bovine Spongiform Encephalopathy “Mad Cow Disease”/ cattle

    -prion diseases in humans (examples):


    -CJD, Creutzfeldt Jakob Disease

    -variant vCJD (from ingestion of BSE/Mad Cow prions)

    2. Viruses: “trouble wrapped in protein” (see fig 18.4 p 472 in Belk’s Biology)

    -genetic info= DNA or RNA

    -protein coat/capsid

    +/- lipid envelope stolen from host cell

    -obligate intracellular parasites; cannot replicate unless inside host cell

    -e.g. smallpox/variola virus, influenza virus, herpes virus,

    HIV/Human Immunodeficiency Virus, West Nile virus, Ebola virus


    Fig 1: virus examples a=”naked” virus b=enveloped virus

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