This is what happens with botulism botulinum

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This is what happens with botulism ( botulinum ) , diphtheria ( Corynebacterium diphtheriae ) , and scarlet fever ( streptococci ). The poisons are produced by the prophages. Other viruses have molecular components such as envelope proteins that are toxic.
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Cold virus v. polio virus Cold viruses attack epithelial tissues, which quickly regenerate after they are damaged. Polio attacks nerve cells, which cannot regenerate Viral Damage and Control Controlling Viruses Some viruses can be prevented by vaccines, e.g., polio, smallpox. Viruses generally can’t be cured , e.g., with antibiotics, because they lack the normal machinery of cells, such as enzymes, etc., on which drugs work. However, because some viruses employ some enzymes that cells do not require, one way to fight viruses is to produce medicines that attack these unusual enzymes. For example, AZT treats HIV by interfering with reverse transcriptase . Acyclovir inhibits the herpes virus’ DNA polymerase, but not cellular DNA polymerase.
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Emerging Viruses: Where do viral diseases come from 3. Epidemics from new exposure . -E.g., HIV and Ebola: These were isolated and unnoticed for decades in Africa. HIV has been spread by changes in the modern world: Increased rapid travel, sexual promiscuity, blood transfusions, drug abuse, etc. Ebola too ! Pandemics = Global Epidemics 1918 Pandemic 1. Mutation : Non-virulent viruses can change into virulent viruses by mutation. For example, RNA viruses, like flu, mutate especially fast because they are often transcribed incorrectly and there is no mechanism to repair the mistakes. 2. Host switching Hantavirus : Normally found in small rodents can spread to humans under special conditions H1N1 (swine flu): An influenza A virus that with small mutations can move among various vertebrate hosts (Spanish Flu of 1918) H5N1 : Another influenza A virus, causing Avian Flu. The H stands for hemagglutinin which is surface protein key for attachment of the virus to a cell host. The N is for neuraminidase which is a enzyme that helps release new viruses from infected cells.
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Are Viruses Alive? They reproduce but not in isolation from cells, and they: Don’t grow – they are only one size from “birth to death” Or develop from one stage to another (like a tadpole to a frog) Or adjust to the immediate environment—no homeostasis Or do most other things living organism do. They do, however, adapt over time via mutations — i.e., they evolve.
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Viroids and Prions: The Simplest Infectious Agents Viroids are small circular RNA molecules that infect plants and disrupt their growth Prions are slow-acting, virtually indestructible infectious proteins that cause brain diseases in mammals. Prions propagate by converting normal proteins into the prion version. Scrapie in sheep, mad cow disease, and Kuru and Creutzfeldt-Jakob disease in humans are all caused by prions. Prion Propagation
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