Koch’s Postulates- Purpose of Koch’s Postulates o Specific infectious diseases are caused by a specific microbeo Help determine etiology of disease  Can help with prevention and treatment!- Origins o Robert Koch’s experiment Isolated microbes from a diseased animal Grows microbes in pure culture - Identifies microbes Microbes are inoculated into a healthy animal in the lab The disease is reproduced in the healthy animal  Microbes are taken from the lab animal and grown in pure culture- Identifies microbes to see if they match the microbes from the diseased animal - Koch’s Postulates o 1) The same pathogen must be present in every case of the diseaseo 2) Pathogen must be isolated and grown in a pure cultureo 3) Pathogen from pure culture must cause disease in the healthy animalo 4) The pathogen must be isolated from inoculated animal and must match the original pathogeno What are some problems with Koch’s postulates? Many infections have the same symptoms  Secondary infections Some organisms don’t get sick from certain microbes  Clean petri plate problem- Some microbes can’t grow in the lab- Microbiotao Symbiotic relationship with the host (us!) o Microbiota protect us Microbial antagonism = competition with other microbes; occupy niches Produce aids and bacteriocins  Probiotics = live microbes applied to or ingested into the body- Produces benefits - Viral Cultures o 1) Mince tissue for culturing o 2) Disaggregation by enzymes o 3) Inoculate cells in a fresh culture mediumo 4) Confluent culture; cells are separated by enzymeso 5) cryopreservation OR subculturing/passaging o Forms viral plagues  Turns purple host cells - white - River’s Modified Postulates o 1) Isolate virus from the diseased host o 2) Cultivate virus in host cello 3) Proof of Filterability  Bacteria = 1-5 micrometers while Viruses = 50-100 nanometers Filter pore separates the two to determine the type of infectiono 4) Production of the comparable diseaseo 5) Reisolation of same virus from inoculated animals o 6) Specific immune responses to virus  Nucleic Acid Based Detection - PCR, quantitative PCR, reverse transcriptase PCR Antibody Based Detection - Proteins made by B lymphocytes - ELISA- Western