New viruses occasionally appear in human populations and can significantly affect public health as evidenced by the pandemic spread of HIV. However, little is known of the ecological and evolutionary factors that impact the population dynamics of emerging viruses. Part of the problem is that it is difficult to conduct experimental studies using pathogenic viruses and their animal hosts because of time, space and ethical constraints. Bacterial viruses and their bacterial hosts provide an easy to manipulate model system to study the dynamics of large virus and host populations over a short time scale.
The proposal specifically addresses several prominent hypotheses regarding the emergence of viruses into new host types. The first aim is to ascertain whether initial virus fitness on the novel host is positively correlated with the probability of emergence. The second aim is to determine whether virus adaptation is enhanced in mixed host communities as compared to communities containing a single host type. The third aim is to establish whether gene flow between virus populations infecting different hosts enhances adaptive evolution. The fourth aim is to investigate the significance of translational adaptation (i.e., evolution of phage codon usage to match host tRNA abundance) in viral emergence. Together these experiments constitute one of the most comprehensive experimental approaches to the study of virus emergence attempted. Successful completion of the work may allow more realistic models of virus emergence and enhance our ability to identify and counteract potentially dangerous viruses.
