Date of Award

1-1-2015

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School/Department

Department of Biological Sciences

Content Description

1 online resource (xiv, 196 pages) : color illustrations

Dissertation/Thesis Chair

Ing-Nang Wang

Committee Members

Paul Turner, Thomas Caraco, Robert Osuna

Keywords

Host Range Evolution, Phage, Recombination, Viruses, Viral genetics

Subject Categories

Biology

Abstract

Most viruses are specialists and have a narrow host range, infecting only a single species or host strain. However, many of the viruses currently responsible for causing emerging infectious diseases are generalists and able to infect a wider host range. Viruses that are able to infect multiple hosts are more likely to continue expanding their host range and infecting additional species. The ability to infect a novel host is a complex process. The first step required to acquire the ability to infect a novel host is host recognition; the host recognition binding protein on the virus must be able to recognize and bind the novel host protein, either in addition to or instead of the original host protein. My study aims to examine this step in more detail using bacteriophages (phages) in order to gain a greater understanding of this process in an attempt to one day predict, prevent, or treat viruses that are likely to expand their host range into humans and cause diseases. I utilize serial passages to perform long term evolution of Lambda, a dsDNA phage often used as a model system. The environment for these passages is made more complex and realistic by the use of multiple host strains and/or the unstructured addition of a second phage, Phi80. These studies examine the dynamics between these two phage populations as they evolve, and demonstrate the presence of multiple evolutionary pathways that are heavily influenced by host environment. Next generation sequencing of some of these evolved phages shows the importance of the often touched upon but rarely examined recombination as a mechanism of changing their host range. Directed recombination reiterates this importance while revealing the ability of recombination to expand the host range of the phage. In conclusion, a more complex environment in the laboratory for evolution studies may reveal the preference of viruses for recombination over point mutations as a method of evolution and changes in host recognition, which is important in the further understanding and prediction of viruses likely to expand their host range and cause emerging infectious diseases.

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