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2.2: Brief descriptions of Microbial Pathogens

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