A Rabbit Model of Acanthamoeba Keratitis That Better Reflects the Natural Human Infection.

Acanthamoeba species are ubiquitous, free-living protozoa that can invade the cornea and result in Acanthamoeba keratitis (AK), a painful progressive sight-threatening corneal disease. Disease progression in current animal models is too rapid to mimic AK in humans accurately. This study provides a novel method for establishing AK in rabbits and compared it with the conventional method with regard to pathogenesis and immune response in humans. The New Zealand white rabbits were randomly divided into two experimental groups (Groups A and B). Rabbits in the Group A (n = 14) received intrastromal injections of 1 × 10(4) /100 µL Acanthamoeba healyi trophozoites (conventional AK model). The Group B animals (n = 14) received microinjections of 1 × 10(4) /10 µL A. healyi trophozoites between the corneal epithelium and Bowman's layer, anterior to the corneal stroma (novel AK model). In addition, two rabbits were left untreated as normal controls. AK in the treated rabbits was evaluated clinically, histopathologically, and immunologically for 35 days. AK was successfully established in both the conventional and novel model groups. Compared with the Group A, AK in the Group B displayed an efficient immune response with less severe pathology. Moreover, the self-limiting but chronic nature of the infection in the Group B was strikingly similar to that of AK in humans. The novel animal model for AK described here more closely simulates the pathogenesis and immune response of Acanthamoeba corneal infection in humans than the animal models currently in use.