Mutant/mutation
In the mutant the endogenous P. berghei  csp (circumsporozoite protein) gene is replaced by the P. gallinaceum csp with introduced SpeI and XhoI sites flanking the repeat region.

Protein (function)
The CS protein is the major protein on the surface of sporozoites and is critical for development of sporozoites within the oocysts and is involved in motility and invasion of both the salivary gland of the mosquito and the liver cells. The protein is also found on the oocyst plasma membrane and on the inner surface of the oocyst capsule. Specific motifs in CS are involved in sporozoite binding to mosquito salivary glands and in sporozoite attachment to heparan sulfate proteoglycans in the liver of the mammalian host. During substrate-dependent locomotion of sporozoites, CS is secreted at the sporozoite anterior pole, translocated along the sporozoite axis and released on the substrate at the sporozoite posterior pole. Following sporozoite invasion of hepatocytes, the CS is released in the host cell cytoplasm.

Phenotype
Normal numbers of oocysts and midgut sporozoites (at day 14 post infection). Strongly reduced numbers of salivary gland sporozoites at day 21 p.i. Sporozoites are not infectious to mice

Additional information
Staining of midgut sporozoites with anti-CSP antibodies showed normal expression,  location. processing and release of the mutated CSP

Figure 1

Figure 1.
Schematic representation of the CS proteins present in each of the four transgenic P. berghei parasite lines generated.
PbCS^DHFR parasites carry the wildtype PbCS coding sequence (white boxes, RI and RII indicated with light and dark green respectively)
PgCS^SX parasites carry the full PgCS coding sequence (grey boxes, RI and RII indicated with light and dark blue respectively), but with the SpeI (S) and XhoI (X) restriction endonuclease sites inserted on either side of the repeat region.
PgCS/Pb^RR parasites contain the PgCS N-terminal and C-terminal regions (grey boxes) and the PbCS repeat region (white box).
PbCS/Pg^CT parasites carry the PbCS N-terminal and repeat regions (white boxes) and the PgCS C-terminal region (grey box).

Other mutants
RMgm-770: A mutant with the endogenous CSP replaced by a chimeric CSP: N- and C-terminal regions of P. galinaceum CSP and the repeat region of P. berghei CSP
RMgm-771: A mutant with the endogenous CSP replaced by a chimeric CSP: the C-terminal region of P. galinaceum CSP and the N-terminal and repeat regions of P. berghei CSP