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):

-Kuru

-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

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

Contributors

Karen Carberry-Goh, D.V.M., Ph.D. (Sacramento City College)