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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Animal Parasitic Diseases Laboratory » Research » Research Project #440184

Research Project: Foodborne Parasites and their Impact on Food Safety

Location: Animal Parasitic Diseases Laboratory

Project Number: 8042-32000-113-000-D
Project Type: In-House Appropriated

Start Date: Apr 29, 2021
End Date: Apr 28, 2026

Objective 1: Describe natural sporulation in coccidian oocysts, including temporal changes in the expression of genes over the course of sporulation and during the degradation of ‘old oocysts’ and morphological changes over the course of sporulation. Sub-objective 1.A. Characterize changes in gene expression as oocysts of E. acervulina mature to their sporulated and infectious state using RNA-Seq to elucidate maturation and identify biomarkers for assaying oocyst viability and infectivity. Sub-objective 1.B: Determine the markers of oocyst senescence by tracking the waning of gene expression and/or the advent of apoptotic signals in E. acervulina. Sub-objective 1.C: Determine whether developmental gene expression patterns established for E. acervulina hold for other Eimeria species infecting poultry. Sub-objective 1.D: Characterize morphological changes of E. acervulina oocysts during sporulation and senescence. Objective 2: Develop assays for coccidian oocyst viability; and using the information from Objective 1, establish gene products strongly up-regulated in infectious, sporulated oocysts of Eimeria. Using comparative genomics, determine homologues in the Cyclospora genome. Sub-objective 2.A: Establish quantitative assays targeting gene products established (above) to undergo the strongest and most consistent up-regulation in mature oocysts of E. acervulina. Sub-objective 2.B: Determine the extent to which these genes’ expression levels predict the infectiousness of oocyst cohorts, using cell culture assays and/or in vivo challenge experiments. Sub-objective 2.C. Identify homologues, in the genome of Cyclospora cayetanensis, of genes consistently and significantly up-regulated in various species of Eimeria infecting poultry. Sub-objective 2.D: Develop quantitative assays designed to measure expression levels of genes deemed most likely over-expressed in mature, infectious oocysts of C. cayetanensis. Objective 3: Evaluate the efficacy of interventions for produce safety using the surrogate. Evaluate known interventions on viability, and on the biomarkers to validate assays for coccidian viability. Sub-objective 3.A: Determine the efficacy of various washing procedures on limiting contamination of produce with oocysts of E. acervulina. Sub-objective 3.B. Improved detection of E. acervulina and C. cayetanensis DNA in contaminating matrices using genome probe capture arrays. Objective 4: Continue to advance the molecular epidemiology of other foodborne zoonotic parasites in livestock and wildlife in the U.S. such as Trichinella in feral swine, pastured swine, and wild carnivores, and Sarcocystis zoonotic species in cattle. Sub-objective 4.A: Determine the efficacy of whole genome and reduced representational sequencing methods to individuate outbreak lineages of Trichinella spiralis. Sub-objective 4.B: Document prevalence of Trichinella in defined compartments of food production and in wild game populations, and the prevalence of anti-Trichinella antibodies in those animals. Sub-objective 4.C: Survey U.S. beef for the presence of Sarcocystis species, including the zoonotic species.

Foodborne parasites exact a serious toll on public health, undermine public confidence in the safety of food, interfere with agricultural marketing and trade, and impose liabilities and exact costs on farmers and food producers. Adopting a “One Health” approach that recognizes commonalities in protecting human, veterinary, and environmental health, we will pursue scientific goals capable of ameliorating burdens imposed by longstanding and emerging problems imposed by parasites contaminating meats and fresh produce. We will first establish a safe and tractable model for Cyclospora cayetanensis, the agent of human cyclosporiasis, using a closely related poultry parasite, Eimeria acervulina. We will use this model to evaluate practical ways to minimize people’s exposure to infection with coccidian oocysts, and will endeavor to supply our regulatory partners with molecular assays to assess parasite viability and infectivity. We will also advance the molecular epidemiology of other foodborne zoonotic parasites in livestock and wildlife in the U.S. such as Trichinella spp. and Sarcocystis zoonotic species. Studies will determine the efficacy of sequencing methods to individuate outbreak lineages of Trichinella spiralis and document prevalence of Trichinella in compartments of food production and in wild game populations. Further studies will analyze the prevalence of Trichinella spp. antibodies in those animals and characterize the presence of Sarcocystis species (including an important zoonotic species) in the U.S. beef supply. Taken together, these studies will address important research gaps and provide powerful tools to producers and food safety regulators for monitoring and ameliorating food safety risks imposed by parasitic infection.