Ookinete motility comparable to wild type. No evidence for ookinete defects in invasion and traversal of the midgut epithelium. Strongly reduced oocyst numbers

Slightly reduced numbers of oocysts

Strongly reduced sporozoite numbers. No infection of mice by the bite of infected mosquitoes

We regularly found large numbers of concavin(-) sporozoites within the salivary glands, however, a large proportion of sporozoites showed an abnormal shape. While wild type sporozoites usually keep the typical curved and slender shape at any time post salivary gland entry, concavin(-) sporozoites rounded up over time. Rounding up of concavin(-) sporozoites was initiated at the posterior end of the cell and hence appeared different to the rounding observed after liver cell entry. Over 90% of oocyst-derived concavin(-) sporozoites were normally formed. Yet with prolonged residency in salivary glands more sporozoites became deformed or rounded up completely. In contrast, we never observed deformed wild type sporozoites, neither in the midgut nor in the salivary gland. Curiously, both deformed and normally shaped sporozoites were still able to move. While normally shaped concavin(-) sporozoites displayed circular movement in a wild type manner with nearly wild type speed, deformed sporozoites progressed with significantly slower speed. Deformed sporozoites also moved on less curved paths as did wild type or normally formed concavin(-) parasites.

Normal/wildtype oocyst development, morphology of oocysts sporozoites and numbers of salivary gland sporozoites. Salivary gland sporozoites showed aberrant morphology and did not show gliding motility (loss of regular shape, extensive membrane blebbing at multiple foci and membrane detachment while organization of cytoskeleton or inner membrane complex (IMC) were not affected).

No infection of mice by the bite of infected mosquitoes

8 of 12 mice that were bitten by concavin(-) infected mosquitoes became infected. In these 8 mice the development of the blood stage infection was delayed by over one day compared to the wild type controls (a loss of 90% infectivity).

Sporozoites were unable to infect mice (after intravenous injection of purified sporozoites).