Adaptation of waterborne echovirus to warm habitats enhances disinfection resistance

Because of their high mutation rate, enteric virus populations excreted from a host are not clonal, but rather consist of a mutant cloud with many different genetic variants. Among these variants, the susceptibility to environmental stressors (e.g., temperature, sunlight, microbial grazing) is expected to differ, and the variants most resistant to environmental stressors are the most likely to persist and encounter a new host. Interestingly, several studies have isolated viruses from the environment with a significantly higher resistance to disinfection compared to the corresponding lab strain. This indicates that environmental persistence and disinfection resistance may be linked. The goal of this study was to determine if exposure to, and persistence under, environmental stress leads to virus resistance to disinfection. Using echovirus 11, we first conducted a series of experimental evolution experiments under different combinations of solar irradiance and temperature, representative of those encountered in temperate and tropical climates. We then determined the persistence of the adapted echovirus 11 populations with respect to thermal inactivation, solar inactivation and microbial grazing, as well as the susceptibility to inactivation by chlorine. None of the adapted populations exhibited enhanced persistence to sunlight or microbial grazing. However, the populations adapted to high temperatures (30 °C) were less prone to thermal inactivation and exhibited a higher capsid stability compared to those adapted to lower temperatures. In addition, the 30 °C-adapted populations were also more resistant to inactivation by chlorine. Interestingly, the mutations associated with thermal stability are commonly found in circulating echovirus 11, indicating a widespread distribution of not only of high environmental persistence, but also disinfection resistance. Overall, our data indicate that viruses that persist in warm surface waters may have enhanced disinfection resistance. As such, disinfection requirements may differ between climate zones, and may change as a function of global warming.


Presented at:
International Water Association - Health-related Water Microbiology, Vienna, September 15-20, 2019
Year:
Sep 15 2019
Publisher:
IWA
Laboratories:




 Record created 2020-03-08, last modified 2020-03-11


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