Orphan drug for acanthamoeba keratitis (ODAK) project: validation of an acanthamoeba polyphaga keratitis model

Abstract

AbstractPurpose Acanthamoeba keratitis is a sight‐threatening infectious disease.The ODAK project (Orphan Drug for Acanthamoeba Keratitis) is a European research project, the objective of which is to assess safety and efficacy of PHMB (polyhexamethylene biguanide) eyedrops to provide the basis for marketing authorisation. The aim of our study is to develop a rat model of Acanthamoeba polyphaga keratitis suitable for this project.Methods Sprague‐Dawley rats were injected in the left cornea stromal layer with Acanthamoeba polyphaga. A subconjunctival injection of 0.57 mg long‐acting betamethasone was administred and clinical examination was performed weekly. One rat was injected with culture media as sham. Corneal scrapings were performed for bacterial and parasitological cultures and real‐time PCR analyses. Paraffin‐embedded corneas were analysed after hematoxylin‐eosin and Schiff periodic acid staining.Results Clinical infections were observed in 7/9 rats (78%). Trophozoites and/or cysts were detected in axenic culture after 1 month in 7/9 rats (78%). Acanthamoeba polyphaga DNA was detected in 7/9 rats (78%) by real‐time PCR. No clinical or microbiologic infection was detected in sham. Histological studies detected trophozoites and/or cysts only in 3/9 rats.Conclusion In this study, a rat model of Acanthamoeba polyphaga keratitis was obtained with good correlation between clinical findings, culture and/or PCR findings. This model was found suitable for assessment of PHMB in animals. The research leading to these results has received funding from the European Union Seventh Framework Programme ([FP7/2007‐2013] under grant agreement n° 305661.