(656d) Utilization of Model Discrimination Analysis in the Description of Bacteriophage Ms2 Viral Dynamics
Lytic phages infect their bacterial hosts, use the host machinery to replicate, and finally lyse and kill their hosts releasing progeny phages. Various mathematical models have been developed that describe these phage-host viral dynamics. For this study, four variations among phage-host viral dynamics models were considered: (1) uninfected cells grew and the infected cells did not grow, (2) uninfected and infected cells grew at the same rate, (3) uninfected and infected cells grew at different rates and (4) infected cells did not grow and the phage-resistant cells developed. The aim of this study was to determine which of these models best described the viral dynamics of lytic RNA phage MS2 and its host Escherichia coli C-3000. Experimental data consisted of uninfected and infected bacterial cell densities, free phage density, and substrate concentration. Parameters of various models were either determined directly from experiments or estimated using non-linear regression analysis. The models were evaluated using a Bayesian-based model discrimination technique. Based on our analysis, the model that predicted the development of phage-resistant cells and the lack of growth of infected cells was found to be the most probable in describing the MS2/C-3000 system. Further analysis showed that the uninfected bacterial population is a quasispecies consisting of phage sensitive and phage resistant bacterial cells rather than a homogenous population of phage sensitive that mutate into resistant bacteria.