Normal numbers of salivary gland sporozoites are formed. Sporozoites have a reduced infectivity to mice as shown by a significant delay of blood infections (prolonged prepatent period) after intravenous inoculation of sporozoites.

Normal numbers of salivary gland sporozoites are formed. Sporozoites have a reduced infectivity to mice as shown by a significant delay of blood infections (prolonged prepatent period) after intravenous inoculation of sporozoites.

Normal numbers of salivary gland sporozoites are produced. Sporozoites are not infectious to mice as shown by the absence of blood infections after inoculation of 50.000 sporozoites.

Normal numbers of salivary gland sporozoites are formed. Sporozoites have a reduced infectivity to mice as shown by a significant delay of blood infections (prolonged prepatent period) after intravenous inoculation of sporozoites.Sporozoites showed normal cell traversal, hepatocyte invasion rates and initial stages of intrahepatic development. The formation of merozoites within the liver schizonts was affected (see 'Additional information'). Intravenous injection of 50.000 sporozoites resulted in breakthrough blood infections in the majority (80100%) of BALB/c mice. All C57BL/6 mice developed a blood stage infection when infected with 50.000 sporozoites. The blood infections show a prolonged prepatency period of 12 days as compared to WT parasites. Assuming a P. berghei blood stage multiplication rate of 10 per 24 h this delay to patency indicates a 9099% reduction in the production and/or infectivity of the fabb/f exo-erythrocytic merozoites.

Normal numbers of salivary gland sporozoites are formed. Sporozoites have a reduced infectivity to mice as shown by a significant delay of blood infections (prolonged prepatent period) after intravenous inoculation of sporozoites.Sporozoites showed normal cell traversal, hepatocyte invasion rates and initial stages of intrahepatic development. The formation of merozoites within the liver schizonts was affected (see 'Additional information'). Intravenous injection of 50.000 sporozoites resulted in breakthrough blood infections in the majority (80100%) of BALB/c mice. All C57BL/6 mice developed a blood stage infection when infected with 50.000 sporozoites. The blood infections show a prolonged prepatency period of 12 days as compared to WT parasites. Assuming a P. berghei blood stage multiplication rate of 10 per 24 h this delay to patency indicates a 9099% reduction in the production and/or infectivity of the fabb/f exo-erythrocytic merozoites.

Growth arrest of late liver stages

Normal numbers of salivary gland sporozoites are produced. Sporozoites are not infectious to mice as shown by the absence of blood infections after inoculation of 50.000 sporozoites. At 12 and 24 h after injection of sporozoites liver stages showed normal development that was indistinguishable from wild type, i.e. they invaded hepatocytes, formed a parasitophorous vacuole (PV), transformed into trophozoites and initiated schizogony. However, by 44 h the size of the liver stages was significantly less than that of wild type. In addition, abnormal progression of nuclear division became apparent. No expression of MSP1 was detected. No mature merozoites are formed and released, resulting in the absence of blood infection.