Examining Committee
Dr. Massimo Marcone, Chair
Dr. Jeffrey Farber, Advisor
Dr. Marc Habash, Co-Advisor
Dr. Lawrence Goodridge, Department Member

TITLE: THE USE OF POTENTIALLY PROBIOTIC BACTERIA FOR THEIR BIOCONTROL EFFECTS ON THE FOODBORNE PATHOGEN HUMAN NOROVIRUS GII.4 AND ITS SURROGATE VIRUS MURINE NOROVIRUS-1

ABSTRACT: Norovirus (NoV) is the foodborne pathogen responsible for the largest number of foodborne illnesses worldwide. The aim of this thesis was to investigate potential probiotic bacteria for their bio-control effects against NoVs in vitro. During initial infectivity experiments no significant increases in BV-2 survival were observed in the potential probiotic treated samples, although some non-significant increases were observed. Due to these initial results, an alternative methodology was selected, namely the ability of the potential probiotics to bind to murine norovirus-1 (MNV-1) and human norovirus GII.4 (HuNoV GII.4). For this, six potential probiotics strains were chosen, and binding was assessed using droplet digital PCR using Enterobacter cloacae as a binding control. Potential binding only occurred when 10³ genome copies/mL of norovirus and 10⁹ CFU/mL of bacteria (probiotic or E. cloacae) was used. Lactobacillus rhamnosus was the only strain to cause a statistically significant reduction in MNV-1 genome copies/mL, indicating that it may be able to bind to MNV-1 under the conditions tested. For HuNoV GII.4, no significant reduction in genome copies were observed with any of the potential probiotic strains and only occurred with E. cloacae, the binding control.