Presentation Title

An Investigation of T7 Coliphage Resistance to Chlorination

Faculty Mentor

Matt Verbyla, Fei Zhao

Start Date

17-11-2018 10:15 AM

End Date

17-11-2018 10:30 AM

Location

C164

Session

Oral 2

Type of Presentation

Oral Talk

Subject Area

biological_agricultural_sciences

Abstract

Chlorine compounds such as hypochlorite, which are used in water disinfection processes, kill pathogens by causing irreversible damage to their proteins and nucleic acids. Recent studies have shown that viruses can evolve to develop increased resistance to chlorine disinfectants and it has been hypothesized that the reason for this is that the viruses develop mutations in their genome. I am testing this hypothesis by subjecting T7 coliphage to a chlorine dose that kills 90% – 99.9% of them, and then regrowing the surviving viruses to understand if this selective pressure induces increased resistance. I plan to repeat this procedure about ten times and get ten different generations to compare to the original coliphage stock. Chlorine blanks were run as negative controls at the same time as the chlorine experiments. The free chlorine concentration was measured using the Hach free chlorine test kit and the phage concentrations before and after chlorination and in the negative controls are measured using the double agar layer plaque assay. The chlorination is done within a set time, currently two minutes, and the reaction is stopped using sodium thiosulfate. After 10 generations, the coliphage genome will be sequenced to determine if any mutations happened, and if the mutations may have contributed to an increased resistance to chlorine treatment. The implications of this research are important for water treatment and public health. A model could be developed to predict the susceptibility of new or unknown viruses using genome data and known chlorine disinfection rates of similar viruses.

Summary of research results to be presented

As of date I am at the third generation. The first time I ran the experiment I added a chlorine dose of ~182 mg-sec/L with about a three log reduction so 99.9% removal. The second and third time I added ~165 and ~126 mg-sec/L chlorine dosage and achieved 99.9% and 90% removal, respectively.

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Nov 17th, 10:15 AM Nov 17th, 10:30 AM

An Investigation of T7 Coliphage Resistance to Chlorination

C164

Chlorine compounds such as hypochlorite, which are used in water disinfection processes, kill pathogens by causing irreversible damage to their proteins and nucleic acids. Recent studies have shown that viruses can evolve to develop increased resistance to chlorine disinfectants and it has been hypothesized that the reason for this is that the viruses develop mutations in their genome. I am testing this hypothesis by subjecting T7 coliphage to a chlorine dose that kills 90% – 99.9% of them, and then regrowing the surviving viruses to understand if this selective pressure induces increased resistance. I plan to repeat this procedure about ten times and get ten different generations to compare to the original coliphage stock. Chlorine blanks were run as negative controls at the same time as the chlorine experiments. The free chlorine concentration was measured using the Hach free chlorine test kit and the phage concentrations before and after chlorination and in the negative controls are measured using the double agar layer plaque assay. The chlorination is done within a set time, currently two minutes, and the reaction is stopped using sodium thiosulfate. After 10 generations, the coliphage genome will be sequenced to determine if any mutations happened, and if the mutations may have contributed to an increased resistance to chlorine treatment. The implications of this research are important for water treatment and public health. A model could be developed to predict the susceptibility of new or unknown viruses using genome data and known chlorine disinfection rates of similar viruses.