Evolutionary Biology BIOL 3350 Dr Lisa Rapaport Lecture 13 Part 2 Notes Evolution and Human Health continued I Influenza A Hemagglutinin and Neuraminidase are anti genic sites or are the sites that the host recognizes B Once a host has an experience with a virus it changes and is able to recognize these proteins in order to build up a defense against the virus C Viruses change the coats of these proteins to make them unrecognizable by the host and viruses try to infect na ve hosts hosts that have not been infected before in order to be successful inside the host and prevent the host from being able to defend against the virus Influenza evolution A Viruses do not have any proof reading mechanism in their RNA B Most mutations are deleterious C The virus population is able to be very effective D If the viruses are mutating the proteins so that the host cannot recognize it we would expect very high mutation rates at those sites of change Tracing origins of pandemic flu strains A They are able to see proteins are most closely related by comparing which proteins have the least amount of different mutations form one another B Those clustered in group 1 are clustered that way because they have C the least amount of differences to one another If you have a virus with H1 then you would expect it to have an N1 as well because they are more closely related to each other D In 1976 the host changed from a pig to a human E All of the viruses that used a horse as a host are grouped together F The swine pig virus is grouped in with humans G Swap of N3 for N2 in the 1968 Northern Territory strain H When a strain of virus jumps from one species to another it is called a Virulence as coincidental evolution A C tetanae is not lethal in all circumstances B Transmission is much more difficult in a solid soil than in liquid or zoonotic virus air Virulence as short sighted evolution A Changing cell types causes very deleterious effects on the host Virulence as a trade off A If a virus is very virulent then the host will die II III IV V VI 1 VII B Being extremely virulent is not a very adaptive strategy for a pathogen because extreme virulence will limit its ability to be transmitted since it causes the host to die Some symptoms are actually an adaptive response to illness A Coughing sneezing and diarrhea are ways to rid the body of pathogens but they are also intense reservoirs for pathogen transmission as pathogens are trying to infect another host 2
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