# Evaluation of eimeria spp. Parasites as surrogates for the study of toxoplasma gondii oocyst inactivation

Laure Augendre, Sandie Escotte-Binet, Dominique Aubert, Anne Silvestre, Jean-Michel Répérant, Isabelle Villena, Aurélien P Dumètre, Stéphanie La Carbona

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Laure Augendre, Sandie Escotte-Binet, Dominique Aubert, Anne Silvestre, Jean-Michel Répérant, et al. Evaluation of eimeria spp. Parasites as surrogates for the study of toxoplasma gondii oocyst inactivation. Apicowplexa, Oct 2022, Bern, Switzerland. . hal-04126144

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Submitted on 13 Jun 2023

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# EVALUATION OF *EIMERIA* SPP. PARASITES AS SURROGATES FOR THE STUDY OF *TOXOPLASMA GONDII* OOCYST INACTIVATION

**Augendre L.**¹, Escotte-Binet S.¹, Aubert D.¹, Silvestre A.², Repérant JM.³, Villena I.¹, Dumètre A.⁴, La Carbona S.⁵

¹EA7510 ESCAPE Epidemiosurveillance and circulation of parasites in the environment, University of Reims Champagne Ardenne,²INRAE, Infectiology and Public Health, University of Tours, ³Virology, Immunology, Avian and Rabbit Parasitology Unit, Ploufragan-Plouzané-Niort Laboratory, ⁴Aix-Marseille University, IRD, AP-HM, IHU-Méditerranée Infection, UMR Vectors - Tropical and Mediterranean Infections, ⁵ACTALIA Food Safety, Saint-Lô

## Why *Eimeria* spp. as putative surrogates of *T. gondii*?

**Oocyst structure**
* 2 sporocysts x 4 sporozoites
* Walls: 2 layers, 90% proteins
* Few lipids and sugars

**Size**
* 11 µm x 13 µm

**Mode of transmission**
* Fecal-oral route

**Pathogenicity to humans**
* Yes

**Definitive host**
* Felids

**Production**
* Difficult to implement
* Quantity depends on the animal

**Oocyst structure**
* 4 sporocysts x 2 sporozoites
* Walls: 2 layers, 90% proteins
* Few lipids and sugars

**Size**
* 14-21 µm x 15-31 µm

**Mode of transmission**
* Fecal-oral route

**Pathogenicity to humans**
* No

**Definitive host**
* Depends on the species
* Ex: chicken, mouse,...

**Production**
* Easy to implement
* Large quantity

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## Results

### Heat treatment impacts on the inner structure (MPL, BP) of *E. acervulina* but not *T. gondii* oocysts

<figure><img src="image_3.png" /><figcaption>Fig 1 : Impact of the different treatments on the structure and permeability of *E. acervulina* and *T. gondii* oocysts obtained by flow cytometry (examples of Heat and NaOH treatments)</figcaption></figure>

- : Decrease in fluorescence vs. Control, + : Increase in fluorescence vs. Control, Ø : No change in

fluorescence vs. Control, — Control (untreated, marked),

— T. gondii (treated, marked),

— E. acervulina (treated, marked),

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Difference between the two parasites, ■ No difference

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## Introduction

* Foodborne diseases are a global public health concern [1]

* *T. gondii*: one of the **most important parasites to consider in the food domain** (multiple routes of infection, high prevalence, worldwide distribution) [2]

* **Oocyst** of *T. gondii*: **resistant** to adverse environmental conditions for **very long periods** [3]. Soil and water can represent **sources of contamination of fresh produce** (i.e vegetables, fruits, shellfish) during primary production and **drinking water** [4]

* **Implementation of control measures** by food industries and/or consumers to **reduce contamination levels** and/or inactivate parasites in foods → Need to assess the efficiency of control measures

* **Problematic**: studies conducted on *T. gondii* are hampered by **financial and ethical constraints** → Efforts are underway to identify and characterize organisms that could be used as surrogates for *T. gondii* oocysts.

## Objectives

* → To determine whether oocysts of the genus *Eimeria* can be used as *T. gondii* surrogates by comparing the response of the two parasites to chemical and physical treatments in an agri-food context

* → Impact of the treatments on the structure (permeability) of oocysts

## Methods

**Permeability assessment**

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## Conclusions and perspectives

* *Eimeria acervulina* has been previously described as a surrogate of *Cyclospora cayetanensis* in some studies [5], [6], [7] → oocysts are **safe to handle and appear to be an economical model for most studies on coccidian contamination**

* The response to different physical and chemical treatments of both parasites was evaluated by measuring the oocysts permeability to different lectins that mark specific layers of the oocysts. **Our results showed that bleaching, NaOH, freezing, 6 freezing cycles have similar effect on E. acervulina and T. gondii oocysts structure.** However, heat treatment impacts differently. This suggest that *E. acervulina* could be representative of *T. gondii* behaviour upon certain treatments but not all. Hence, different surrogates could be required depending on the treatment that has to be assessed. Other *Eimeria* species are currently tested.

* To validate *Eimeria* oocysts as surrogates of *T. gondii*, the next essential step is to compare the inactivation kinetics of both parasites upon different treatments. Such assessment requires to measure viability and/or infectivity of *Eimeria* oocysts. Finally, molecular responses (transcriptomic, proteomic) could also be evaluated to describe the potential surrogate with accuracy.

## References

[1] WHO, (2019) https://www.who.int/

[2] Charvat, R. A., Arrizabalaga, G. (2016). Oxidative stress generated during monensin treatment contributes to altered *Toxoplasma gondii* mitochondrial function. Nature Publishing Group, 1–17

[3] Shapiro K., Bahia-Oliveira L., Dixon B., Dumètre A., de Wit L.A., VanWormer E., Villena I. (2019). Environmental transmission of *Toxoplasma gondii*: Oocysts in water, soil and food. Food and Waterborne Parasitology

[4] FAO/WHO, (2014). Multicriteria-based Ranking for Risk Management of Food-borne Parasites.

[5] Kniel E., Shearer A., Cascarino L., Wilkins C., Jenkins C. (2007) High Hydrostatic pressure and UV light treatment of produce contaminated with *Eimeria acervulina* as a *Cyclospora cayetanensis* surrogate. Journal of Food Protection, Vol. 70, No. 12, Pages 2837-2842

[6] Shearer, A.E.H., Wilkins, G.C., Jenkins, M.C., and Kniel, K.E. (2007). Effects of high hydrostatic pressure on *Eimeria acervulina* pathogenicity, immunogenicity and structural integrity.

[7] Lee M. B., and E. H. Lee. (2001). Coccidial contamination of rasp-berries: mock contamination with *Eimeria acervulina* as a model for decontamination treatment studies. J. Food Prot. 64:1854-1857.