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Explore the structures and functions of viruses and prions, including their interaction with host cells, reproduction cycles, immune responses, historical impacts, and the emergence of diseases like smallpox and 1918 flu pandemic.
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STRUCTURE • DNA strand or RNA strand • Covered by a Capsid • Capsid (protein covering)
Function of Structures • DNA or RNA incorporate into host DNA • Use the host proteins (enzymes, etc.) to reproduce • Once reproduced to a certain level – burst to infect other cells • Capsid (covering) – identify host to attach and enter cells • Capsid – also is portion that immune system identifies to attack the virus.
HOSTS • required for reproduction • All types of organisms may be hosts • Usually specific hosts
Cycles • Lytic Cycle – infect, reproduce, and lyse (break-open the cell) – influenza, HPV • Lysogenic Cycle- infect, remain dormant (“hidden”) in the cell, a trigger will cause the viruses to begin growing and go through the lytic cycle (bursting) to release more viral particles. (Shingles, HIV) • Amoeba Sisters Summary • https://s-media-cache-ak0.pinimg.com/originals/e2/0f/50/e20f508e9c5a5fcd5eb7d02f0600c823.jpg
VIRUSES • Some deadly • Smallpox – viral infection • 20-60% fatality rate overall • 80% in children • Responsible for 300-500 million deaths during the early 20th century • Eradicated in 1979 (Somalia)
Immune Response • Antigenic (protein) surface markers on capsid cause an immune response • Immune system produces antibodies to attack the infection. • Memory: If re-infected the immune system remembers the antigen & will attack the virus before you get sick.
Edward Jenner and Vaccinations • milk maids had immunity to smallpox • Hypothesis: Milkmaids exposed to a less virulent (dangerous) form of the virus (cowpox) had immunity to smallpox. • injected a boy with cowpox- the boy got sick but recovered. • then injected the boy with smallpox – the boy did not get sick!
How vaccines work • Vacca- Latin for cow • Contains an agent that resembles the disease-causing microbe • Causes an immune response – if get exposed to virus the immune system remembers it and destroys the virus before the host gets sick.
1918 Flu Pandemic I had a little bird its name was EnzaI opened the window And in-flu-enza -poem 1918
Definitions • Endemic –regularly found in a population • Epidemic -widespread occurrence at a certain time. • Pandemic - world. • Virulence /pathogenicity– severity epi = on, upon, above Demic – relating to people or district Pan=all En= within
Definitions • Vector –(carrier) organism that transmits a disease or parasite • Reservoir (disease) – host- infectious agent normally lives and multiplies • Zoonotic Infections- disease that can be transmitted from animals to people (rabies, SARS, influenza, Lyme disease)
1918 Spanish flu • Killed > Great War or World War I • 38 million from WWI/50 million from 1918 flu • 1/3 of the World Population Infected (500 million) • Normally influenza has a 0.1% fatality rate, but 1918 had increased virulence because of new mutations- all those that may have been immune with a slight mutation were not. • Economic impacts and impacts to the war effort
Prions • protein particle • transmissible spongiform encephalopathies (TSE) which -neurodegenerative diseases. • Most commonly known- Mad Cow Disease, Scrapie, CJD, Kuru • Ceph- head – https://www.youtube.com/watch?v=ujK7KiLt0s8