<i>s2p(-)</i> parasites show delayed transmission and growth, resulting in reduced virulence.

<p>(A) Kaplan-Meier analysis of time to patency after inoculation of 10,000 WT or <i>s2p(-)</i> salivary gland sporozoites into C57BL/6 mice (WT n = 9, <i>s2p(-)</i> n = 13). **, <i>P</i> < 0.01 (Log rank [Mantel-Cox] test). (B) Blood stage growth curve of the same mice showing the difference in growth rate of WT <i>vs</i>. <i>s2p(-)</i> parasites, alongside blood stage development of mice infected through bite back from infected <i>A</i>. <i>stephensi</i> mosquitoes (Wt bb <i>vs</i>. <i>s2p(-)</i> bb). In all cases mean values (± SD) are shown. **<i>P</i> < 0.01, ***<i>P</i> < 0.001 (Multiple t-test comparison). Significance is shown as follows: Black stars: Sporozoite injection experiment, Grey stars: Bite back experiment. (C) Kaplan-Meier curve of mice developing experimental cerebral malaria (ECM) over time after injection of 10,000 WT or <i>s2p(-)</i> salivary gland sporozoites (WT n = 9, <i>s2p(-)</i> n = 13). ***, <i>P</i> < 0.001 (Log rank [Mantel-Cox] test). (D, E) Parasitaemia levels of C57BL/6 mice after infection with (D) 10,000 (<i>n</i> = 3 each) or (E) 1,000 (<i>n</i> = 5 each) WT or <i>s2p(-)</i> iRBCs, respectively, as determined by Giemsa stained blood smears. <i>s2p(-)</i> parasites exhibit slower growth rates compared to the WT line. Mean values (± SD) are shown *<i>P</i> < 0.05 **<i>P</i> < 0.01, ***<i>P</i> < 0.001 (Multiple t-test comparison). (F) Kaplan-Meier curve of time to ECM development after patency. A one day delay in ECM symptoms was observed in mice infected with 10,000 <i>s2p(-)</i> iRBCs (<i>P</i> = 0.11 (Log rank [Mantel-Cox] test). Mice infected with 1,000 WT iRBC developed ECM symptoms at day 8 (4/5) and 9 (1/5), while 2/5 <i>s2p(-)</i> infected mice developed ECM at day 11 and 3/5 remained free of ECM symptoms. **<i>P</i> < 0.01 (Log rank [Mantel-Cox] test).