BOLOGY 107 Lecture 36Outline of Last Lecture I. Viruses a. Life cycleb. Bacteriophages c. Treatment d. Retroviruses Rapid adaptation Outline of Current Lecture II. Viruses a. HIVIII. Viroids and Prionsa. Viroids b. PrionsCurrent LectureViruses1) HIVa) Invades immune system cellsi) White blood cellsb) Can exist as a provirusi) Integrates DNA into the host genomec) RTase is error pronei) High mutation rate – fast evolutionii) By the time the immune system responds, the virus cannot be recognized(1) Vaccines are useless, become quickly drug resistanced) Treatment- target all stepsi) RTase inhibitors(1) Dideoxynucleotides prevent elongation, lead to early termination(a) Example: AZT, has no 3’ OH to continue chainii) Irreversible inhibition of enzyme(1) Protease inhibitors(a) Envelope proteins must be cut, blocks protease to cut so no new virus forms (2) Fusion inhibitorsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.(a) Blocks the envelope from fusing with the host cell, virus cannot get close enough to fuse(3) Integration inhibitorsiii) Problems with current treatments(1) High mutation leads to high resistance(a) Combated by administering a multi-drug regimen making it difficult to adapt to all three (the usual number in a combination)(2) HIV drugs are designer drugs(a) Many cannot afford the regimensViroids and Prions2) Virodsa) Small, circular, naked ssRNAi) No proteinsii) ~ 250-450 nucleotidesiii) Base pairs with itselfb) Found in plantsi) Cross cell wall and membrane freelyii) Use mRNA transcription machinery to make copies of self3) Prionsa) “Infectious” proteinsi) Misfolded versions of normal proteinsii) No genetic materialiii) Very stable – cannot be denatured by normal meansb) Occur from rare spontaneous misfoldingi) Mutations in the protein make this more likelyii) Can be induced by another copyc) Autocatalytic – cause normal proteins to misfoldi) Aggregate and interfere with normal neuron function(1) Cells die, leaving the brain looking like a sponged) Often degenerative brain diseasesi) Things like scrapie or Creutzfeld-Jacob Diseasee) Can be trans-speciesi) Scrapie infected cows, cows got mad cow disease, humans ate infected beef, humans got Creutzfeld-Jacob
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