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Author ORCID Identifier

https://orcid.org/0000-0002-0323-3390

AccessType

Open Access Dissertation

Document Type

dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Food Science

Year Degree Awarded

2023

Month Degree Awarded

September

First Advisor

Matthew Moore

Second Advisor

Lynne McLandsborough

Third Advisor

John Gibbons

Fourth Advisor

Jiakai Lu

Fifth Advisor

Mandy Muller

Subject Categories

Environmental Microbiology and Microbial Ecology | Food Microbiology | Other Microbiology | Virology

Abstract

Viruses, owing to their ubiquitous nature and ability to infect almost every other species, have long been a subject of interest for scientists. Some of the virus species can be very deadly to humans and animals alike and can impose a huge economic and health burden across the world. The recent CoVID-19 pandemic underscores the importance of timely detection for developing effective intervention strategies. Unfortunately, some of the virus species that cause significant health and economic impacts do not have robust and reliable detection methods due to several reasons. In some cases, despite having gold standard methods for detection of viruses, lack of effective upstream sample preparation steps could result in underestimating the viral loads. Sample preparation prior to detection is an often-overlooked aspect of foodborne virus detection. The sample preparation step is very crucial especially when food and environmental samples are involved due to the small number of infectious virus particles in a large volume of sample (eg. Fresh produce and sewage). Earlier studies have shown that representative gut bacteria strains can capture human norovirus from environmental samples. But the capture efficiency is largely dependent on the culture media conditions. The current study focuses on this aspect of sample concentration prior to detection using engineered bacterial strains. We have demonstrated that using engineered bacterial strains could effectively improve the capture efficiency of human norovirus particles from stool samples. We noticed an upwards of 65% capture efficiency with all the engineered clones we tested. This is much higher compared to that of conventional PEG or magnetic bead-based methods wherein the capture efficiencies are E. coli-based capture method can be scaled up to accommodate larger sample volumes. The engineered E. coli-based capture and concentration technique is also not susceptible to change in media conditions as the inducible expression of norovirus specific peptides expressed on the surface can be fine-tuned. This is the first time ever someone has used engineered E. coli for capture and concentration of human norovirus from environment samples. Moreover, the ease with which the engineered bacteria can be cultured and utilized for capture of norovirus makes it an ideal method for sample concentration prior to detection in resource limited settings. Control of environmentally transmissible viruses is an important aspect from a public health standpoint. To achieve this, conventional disinfection strategies employ a wide variety of chemical compounds which can often be detrimental to human health. To circumvent this issue, we propose the use of novel disinfection strategies that employ engineered water nanostructures for neutralizing both foodborne and environmental viruses. The residue-free disinfection methods proposed can be employed in a food industry setting without any problem. The EWNS cocktails used in this study showed more efficacy against a coronavirus surrogate and vegetative bacteria than MS2. Miniscule amounts of active ingredients were required to achieve inactivation of pathogens on high touch surfaces. Targeted and precise delivery of active ingredients is superior to conventional “wet” treatments. With the EWNS system, we were able to achieve complete inactivation of the SARS-CoV-2 surrogate HCoV229E after just 1 minute exposure. This demonstrates the potential of the EWNS system as an effective method for inactivating viruses on surface. The potential of EWNS for air disinfection is currently being tested. We also highlight the importance of using UV-C based disinfection methods for combating environmentally significant viruses. We tested the efficacy of 4 different commercially available UV-C light-based systems for their disinfection capacity. The two handheld devices we tested lived up to their claims of disinfecting viruses on surfaces. The airborne inactivation results show promise for occupational deployment of ceiling-based UVC 222 nm technology for a high level of SARS-CoV-2 inactivation in the air within a short time. But the potential for UV-C based disinfection techniques requires further scrutiny.

DOI

https://doi.org/10.7275/35911980

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

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