BIOEE 1780 Chapter Notes - Chapter 18: Coinfection, Smart Key, World War I
9 Dec 2016
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Ex: cytomegalovirus (hcmv or human herpes virus) relationships among viruses mirrors the relationships of their hosts as that ancestor"s descendants diverged into new lineages, the virus diverged as well; did not leap to distantly related animals, it adapted. Hiv does not mirror that of its host. Pathogens face a trade-off: adaptations that make them better adapted to spread in a new species will make them less fit in their original host evolution of host shift represents a major threat to human health. Attenuation: they mix viruses with the cells of monkeys or chimps. The viruses mutate as they replicate, and selection favors the strains best adapted to these nonhuman hosts. At the same time, the viruses become less suited to infecting humans. Once the viruses have become weak enough, they can be injected safely into people. They can then trigger a strong immune response, but they no longer make people sick.
