The effect of solar insolation on Cryptosporidium oocyst infectivity and sporozoite intracellular calcium.

A microcosm experiment was performed on a clear sky day with a solar UV index maximum of 11 in order to investigate changes oocyst infectivity and sporozoite intracellular calcium. Oocyst microcosms were sampled at two levels of insolation (T1 and T2) (see Table S1). A) Oocyst infectivity was determined using a cell culture TaqMan PCR infectivity assay for both dark and light irradiated oocysts. Non-irradiated oocysts kept at 4°C were used as controls, and treatments calculated as a percentage of the control. B) Oocysts were excysted and sporozoites incubated in supplemented medium at 37°C for 90 minutes before staining with the intracellular calcium indicator Fluo-4 AM and then analysed by flow cytometry. Sporozoite intracellular calcium is expressed as arbitrary units. An asterisk above a pair of bars indicate statistically significant effects (t-test, P<0.05). Error bars indicate standard deviations (n = 3).