Date of Graduation

12-2014

Document Type

Thesis

Degree Name

Master of Science in Food Science (MS)

Degree Level

Graduate

Department

Food Science

Advisor

Kristen E. Gibson

Committee Member

Steven C. Ricke

Second Committee Member

Jeffrey Silberman

Keywords

Acanthamoeba, Food Safety, Fresh Produce, Norovirus

Abstract

Human noroviruses (HuNoV) are the most common cause of foodborne disease outbreaks in the United States and the most common food commodities implicated in HuNoV outbreaks are leafy greens; however, the vehicle of transmission and point of contamination are often unknown. Here, we hypothesize that common free-living amoebae (FLA) ubiquitous in the environment may act as reservoirs of HuNoV and facilitate the transmission of these pathogens to fresh produce. The objective of this research was to first evaluate the interaction/association between HuNoV surrogates and Acanthamoeba by incubating them together and analyzing virus titer associated with amoeba through an 8 day period and a complete life cycle. Also, the location of associated virus in/on amoeba was investigated. Last, the transfer of virus-associated amoeba from the environment to fresh produce was evaluated.

In conclusion, A. castellanii can interact with a HuNoV surrogate, murine norovirus type 1 (MNV-1) and associate with MNV-1 for 8 days and even through the complete amoeba life cycle. In addition while viruses were still infectious, immunofluorescence staining results indicated that MNV-1 changed its location from amoeba surface to inside amoeba over 24 hours. Finally, the transfer of virus-associated amoeba from water to fresh produce was notable. Based on the data we presented, A. castellanii appears to have potential for carrying MNV-1 and transfer it to fresh produce in water and therefore, possibly playing a role in the transmission of HuNoV from aquatic environment to fresh produce.

The findings of this study are significant in understanding the HuNoV survival in the environment and for the future control of HuNoV outbreaks where FLA may serve as important reservoirs.

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