Attachment and survival of viruses on lettuce (Lactuca sativa L. var. capitata L.): role of physicochemical and biotic factors
Year: 2006
Type: dissertation
Abstract: Enteric viruses are responsible for a significant amount of foodborne disease in\nthe United States. Foodborne disease associated with enteric viruses has been\nincreasing within the last few years due to technological advances and raised\nawareness. Salads and salad crops are the principal vector for transmission of\nenteric viruses. The objective of this study was to determine if viruses are able to\nattach non-specifically to the surface of lettuce and to determine the forces\nresponsible for non-specific viral adsorption to lettuce. Additionally, the impact\nof the microbial flora on viral persistence was studied to determine the effect on\nviruses. The four viruses studied were echovirus 11, feline calicivirus, MS2 and\nφX174. The viruses were chosen based on their varying isoelectric points and\nsimilar physicochemical attributes. The isoelectric point was not the main factor\ndetermining virus attachment to lettuce. Viruses had varying attachment\nefficiencies, with echovirus 11 having the highest affinity to lettuce and φX174 the\nleast. Viral adsorption to lettuce was mediated by electrostatic forces due to the\nremoval of virus adsorption at pH 7 and 8 with the addition of 1 M NaCl to the\nbuffer solutions. Microcosm studies indicated that the microbial flora did not have a negative impact on virus survival. The bacteriophages had the highest\nsurvival rate. Virus survival in the microcosm studies was not indicative of virus\nsurvival on the surface of the lettuce. The animal viruses exhibited survival rates\ngreater than or equal to the survival of bacteriophages at 4° C, but at room\ntemperature viable animal viruses rapidly declined compared to the\nbacteriophages. Additional studies also indicated that the microbial flora was\nnot able to degrade the viruses for aerobic microbial growth. Overall, these\nresults indicate that viruses are able to attach to the surface of lettuce, providing\na possible explanation for the high incidence of virus associated disease\ninvolving salads and fresh produce. More importantly the use of surrogates for\nvirus studies involving fresh produce must be re-evaluated, because of the lack of\ncorrelation between animal viruses and bacteriophages. Appropriate viral\nsurrogates, if used, have to be carefully chosen based on viral physicochemical\nproperties as well as the infectious route of the virus.
Author: Everardo Vega
Language: English
Subfield: Food Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: green
OpenAlex ID: W2292150135