Abstract
Ocular toxoplasmosis is the principal cause of posterior uveitis and a leading cause of blindness. Animal models are required to improve our understanding of the pathogenesis of this disease. The method cur-rently used for the detection of retinal cysts in animals involves the observation, under a microscope, of all the sections from infected eyes. However, this method is time-consuming and lacks sensitivity. We have developed a rapid, sensitive method for observing retinal cysts in mice infected with Toxoplasma gondii. This method involves combining the flat-mounting of retina – a compromise between macro-scopic observation and global analysis of this tissue – and the use of an avirulent recombinant strain of T. gondii expressing the Escherichia coli b-galactosidase gene, visually detectable at the submacroscopic level. Single cyst unilateral infection was found in six out of 17 mice killed within 28 days of infection, whereas a bilateral infection was found in only one mouse. There was no correlation between brain cysts number and ocular infection.