Virology lecture #22: Evolution
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evolution
A plant virus that switched to vertebrates
Viruses can be transmitted to completely new host species that they have not previously infected. Usually host defenses stop the infection before any replication and adaptation can take place. On rare occasions, a novel population of viruses arises in the new host. These interspecies infections can sometimes be deduced by sequence analyses, providing a glimpse …
TWiV #78: Darwin gets weird
Hosts: Vincent Racaniello, Alan Dove, Dickson Despommier, and Rich Condit Vincent, Alan, Dickson, and Rich talk about treating arthritis with a tanapox virus protein, Darwinian evolution of prions in cell culture, and the connection between cold weather fronts and outbreaks of avian H5N1 influenza in Europe. This episode is sponsored by Data Robotics Inc. Use …
Influenza PB1-F2 protein and viral fitness
The second RNA segment of the influenza virus genome encodes the PB1 protein – part of the viral RNA polymerase – and, in some strains, a second protein called PB1-F2. The latter protein is believed to be an important determinant of influenza virus virulence. The absence of a full-length PB1-F2 protein has been suggested as …
Reassortment of the influenza virus genome
Mutation is an important source of RNA virus diversity that is made possible by the error-prone nature of RNA synthesis. Viruses with segmented genomes, such as influenza virus, have another mechanism for generating diversity: reassortment. When an influenza virus infects a cell, the individual RNA segments enter the nucleus. There they are copied many times …
The trajectory of evolution
Scientists and philosophers have long debated the trajectory of evolution. Some of the questions they consider include: is there a predictable direction for evolution, and if there is, what is the pathway? Are there evolutionary dead ends? Viruses are excellent subjects for the study of evolution: they have short generation times, high yields of offspring, …