Intracellular Ca~(2+) level changes and apoptosis during internalization of {\sl Leptospira interrogans}
Intracellular free Ca~(2+) levels in the J774A.1 cells infected with L. interrogans strain 56601 rapidly elevated with a double peak curve and the two peak fluorescence intensity change percentages were (747.5±35.7)% and (804.6±40.8)%, respectively. Intracellular free Ca~(2+) levels in the J774A.1 cells infected with L. interrogans strain 56608 slowly risen with a single slope-like curve and its maximum of fluorescence intensity change percentages was (402.4±23.6)%, which was significantly lower than those in the cells infected with L. interrogans strain 56601 (P<0.01). Apoptosis rates in the Vero cells adhered with living and UV-killed L. interrogans strain 56601 were 84.5% and 78.2%, respectively, while in J774A.1 cells with the same treatment were 34.5% and 30.9% respectively.