Assessing Toxoplasma gondii oocyst infectivity using a sporocyst-based cell-culture assay combined with qPCR for environmental applications.

The objectives of this study were (i) to develop a reliable method, applicable in biomonitoring, for the rapid detection of infectious oocysts by cell culture of their sporocysts combined with qPCR (sporocyst-CC-qPCR), and (ii) to adapt this method to blue and zebra mussels experimentally contaminated by oocysts with the objective to use these organisms as sentinels of aquatic environments. Combining mechanical treatment and bead beating leads to the release of 84 ± 14% of free sporocysts. The sporocyst-CC-qPCR can detect fewer than ten infectious oocysts in water within four days (one day of contact and three days of cell culture), compared to four weeks by mouse bioassay. For both mussel matrices, oocysts were pre-purified using a 30%-Percoll gradient and treated with sodium hypochlorite before cell culture of their sporocysts. This assay was able to detect as low as ten infective oocysts. This sporocyst-based CC-qPCR appears as a good alternative to mouse bioassay for monitoring infectious T. gondii oocysts directly in water but also using biosentinel mussel species. This method offers new perspective to assess the environmental risk for human health associated to this parasite.Importance: The ubiquitous protozoan Toxoplasma gondii is the subject of renewed interest, due to the spread of oocysts in water and food causing endemic and epidemic outbreaks of toxoplasmosis in humans and animals worldwide. Displaying a sensitivity close to animal models, cell culture represents...
Source: Applied and Environmental Microbiology - Category: Microbiology Authors: Tags: Appl Environ Microbiol Source Type: research