The system of E. coli and its virus, phage lambda, has long served as a paradigm for cell-fate bifurcation. As a temperate phage, upon infecting an E. coli cell, lambda can choose either the lytic (virulent) pathway producing ~100 new progeny particles and lysing the cell, or the lysogenic (dormant) pathway with its DNA integrated into the host chromosome and replicating along with the host. Recent single-cell, single-molecule studies have yielded many interesting findings including individual phage voting, interplay of phage competition and cooperation. We are interested in formulating a quantitative picture of the lysis-lysogeny decision making. In addition, we have expanded our studies to other temperate phages such as P1. We aim to elucidate the fundamental mechanisms of these systems, which will shed important light on phage therapy treating multi-drug resistant bacteria and how other viruses operate in the host including higher organisms.

ssRNA phages are small viruses which infect bacteria through retractile pili. We are particularly interested in the entry dynamics of genomic RNA from the phage capsid to the cell, virus replication and assembly inside the cell, and the impact on the retractile pili as a result of ssRNA phage infection. We aim to understand these fundamental processes and to engineer these phages as novel antibacterials.