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Clemson BIOL 3350 - Viruses and Their Transmittance
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Biol 3350 1st Edition Lecture 20Outline of Last Lecture I. Mechanisms of Kin RecognitionII. Associative Learning III. Phenotype MatchingIV. Recognition AllelesV. Eusocial SocietiesVI. Honey Bee ColoniesVII. Naked Mole RatsVIII. Importance of Evolution for Human HealthIX. How do bacteria acquire resistance?X. Antibiotic ResistanceOutline of Current Lecture I. InfluenzaII. Influenza EvolutionIII. Tracing Origins of Pandemic Flu StrainsIV. Virulence as Coincidental EvolutionV. Virulence as Short-Sighted EvolutionVI. Virulence as a Trade-OfVII. Trade-Ofs: PredictionsVIII. Overdominance and DiseaseIX. Some symptoms are actually an adaptive response to illnessCurrent LectureI. Influenzaa. Influenza viruses have proteins on the surface of their cell, called coat proteins (ex. Hemagglutinin and neuraminidase)b. Antigenic sites are the places on the coat of the virus that the proteins bind toc. Our immune systems changes once it has experience with virus, and form defenses that recognized the coat proteins next timed. Change the structure of those coat proteins or attack cells that have not been exposed to these proteins before in order for viruses to be efectivee. Enters the nucleus and is able to use the machinery to create new baby viruses (RNA copies)f. New proteins are coated in sialic acidII. Influenza EvolutionThese 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. There is so many of them and they reproduce so quickly that even with the high deleterious rate, the virus populations are very efectiveb. Most mutations are deleteriousc. Viruses do not have proofreading mechanisms in their RNAd. They looked at amino acid replaced (nonsynoymous replacement) à found that in the surviving lineages, there were more mutations at the sites where selective pressures were acting on the proteins than the extinct lineages III. Tracing Origins of Pandemic Flu Strainsa. They are able to see which proteins are most closely related by comparing which proteins have the least amount of diferent mutations from one anotherb. Closely related strains tend to infect the same hostc. Example: H1 and N1 both infected together due to similar clustering à these areproteins on the same virus; if H1 is present on the virus, N1 is also thered. The host was a pig for most of the H1N1 infections until 1976 when this virus infected a humane. Not all strains that infected pigs were H1N1 à H3N2 in 1982f. The swine viruses mixed in with avian and human strainsg. Gene swapping occurs inside the vessel of a pig à once the gene swapping has occurred, it is more likely for us as humans to get that virush. Zoonosis – when gene swaps from one species to anotherIV. Virulence as Coincidental Evolutiona. Virus needs to be very virulent to get transmitted at allb. The virulence of some pathogens in humans may be an accidenti. There is no direct selection for them in humansV. Virulence as Short-Sighted Evolutiona. When virus switches from one type of cell to another type of cell to infect, there is no competition from other virusesb. Pathogens may evolve in a host for many generations, leading to new strains thatbenefit them in a host, but are unlikely to be transmittedVI. Virulence as a Trade-Ofa. If you are very virulence and your host dies, you can move and reproduceb. Being very virulent is not an adaptive strategy because it will limit their transmittance abilityc. Balance between virulence and transmissiond. Natural selection should favor pathogens that balance between virulence within a host and ability to be transmitted to new hostsVII. Trade-Ofs: Predictionsa. Pathogens that are transmitted directly should have lower virulence, low numbers of deaths b. Pathogens transmitted by vectors may evolve higher virulenceVIII. Overdominance and Diseasea. Some diseases are maintained by overdominance because there is a heterozygote advantagei. Sickle cell anemiaii. Cystic fibrosisb. Selection favors the heterozygote, but also results in some homozygous individualsIX. Some symptoms are actually an adaptive response to illnessa. Body tries to get rid of the pathogens quickly using means of coughing, sneezing, diarrhea à allows the pathogens to be transmitted elsewhere; high reservoirs of transmittanceb. Low/moderate fever is body’s adaptive response to get rid of the


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Clemson BIOL 3350 - Viruses and Their Transmittance

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