In experimental cultures, when bacteria are mixed with lytic (virulent) bacteriophage, bacterial cells resistant to the phage commonly emerge and become the dominant population of bacteria. Following the ascent of resistant mutants, the densities of bacteria in these simple communities become limited by resources rather than the phage. Despite the evolution of resistant hosts, upon which the phage cannot replicate, the lytic phage population is most commonly maintained in an apparently stable state with the resistant bacteria. Several mechanisms have been put forward to account for this result. Here we report the results of population dynamic/evolution experiments with a virulent mutant of phage Lambda, λVIR, and Escherichia coli in serial transfer cultures. We show that, following the ascent of λVIR-resistant bacteria, λVIRis maintained in the majority of cases in maltose-limited minimal media and in all cases in nutrient-rich broth. Using mathematical models and experiments, we show that the dominant mechanism responsible for maintenance of λVIRin these resource-limited populations dominated by resistant E. coli is a high rate of either phenotypic or genetic transition from resistance to susceptibility—a hitherto undemonstrated mechanism we term "leaky resistance." We discuss the implications of leaky resistance to our understanding of the conditions for the maintenance of phage in populations of bacteria—their “existence conditions.”.
Chaudhry W, Pleska M, Shah N, et al. Leaky resistance and the conditions for the existence of lytic bacteriophage. PLoS Biology. 2018;16(8). doi:10.1371/journal.pbio.2005971
Chaudhry, W., Pleska, M., Shah, N., Weiss, H., Mccall, I., Meyer, J., … Levin, B. (2018). Leaky resistance and the conditions for the existence of lytic bacteriophage. PLoS Biology. Public Library of Science. https://doi.org/10.1371/journal.pbio.2005971
Chaudhry, Waqas, Maros Pleska, Nilang Shah, Howard Weiss, Ingrid Mccall, Justin Meyer, Animesh Gupta, Calin C Guet, and Bruce Levin. “Leaky Resistance and the Conditions for the Existence of Lytic Bacteriophage.” PLoS Biology. Public Library of Science, 2018. https://doi.org/10.1371/journal.pbio.2005971.
W. Chaudhry et al., “Leaky resistance and the conditions for the existence of lytic bacteriophage,” PLoS Biology, vol. 16, no. 8. Public Library of Science, 2018.
Chaudhry W, Pleska M, Shah N, Weiss H, Mccall I, Meyer J, Gupta A, Guet CC, Levin B. 2018. Leaky resistance and the conditions for the existence of lytic bacteriophage. PLoS Biology. 16(8), 2005971.
Chaudhry, Waqas, et al. “Leaky Resistance and the Conditions for the Existence of Lytic Bacteriophage.” PLoS Biology, vol. 16, no. 8, 2005971, Public Library of Science, 2018, doi:10.1371/journal.pbio.2005971.
All files available under the following license(s):
Creative Commons Attribution 4.0 International Public License (CC-BY 4.0):
2018_Plos_Chaudhry.pdf 4.01 MB