Mutant/mutation
In the mutant the P. berghei csp gene has been replaced with the P. falciparum csp gene (using the construct pR-CSPfFL containing the P. falciparum csp coding region with a P. berghei signal sequence, the hDHFR selection cassette, and csp 5'and 3'untranslated regions (UTRs)).  In addition, a single nucleotide in the csp gene of plasmid pIC-CSPfFL-CD8CT was replaced to incorporate a cytotoxic epitope that is not present in the P. falciparum 3D7 strain. In summary, the CSP amino acid sequence in the transgenic line consists of the signal sequence of the P. berghei CSP (amino acids 1 to 23) followed by residues 25 to 397 from the P. falciparum 3D7 CSP.
In addition, the mutant expresses the fusion protein GFP-luciferase under control of the eef1α promoter.

Protein (function)
he 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
From the paper:

'This transgenic P. berghei line expresses the full-length P. falciparum 3D7 CSP. However, in the region containing the sequence ₃₅₉DYANDIEKKI₃₆₈, the A residue in position 361 was replaced by E to encode ₃₅₉DYENDIEKKI₃₆₈, which is a murine H-2Kk cytotoxic epitope present in different P. falciparum strains such as 7G8 or T4. The sequence found in the 3D7 strain (₃₅₉DYANDIEKKI₃₆₈) is not recognized as a murine Class I MHC epitope. This new transgenic parasite strain, P. berghei-P. falciparum CSP-full-length CD8 C-terminus (P.b.-P.f. CSP-FL CD8CT), develops normally in Anopheles stephensi mosquitoes and can efficiently infect naïve mice through mosquito bites'

'In this study, we evaluated the immunogenicity and protective capacity of full-length recombinant Plasmodium falciparum circumsporozoite protein administered with the novel cationic liposomal adjuvant system CAF09. Using newly developed transgenic rodent malaria parasites expressing the full-length Plasmodium falciparum circumsporozoite protein, we demonstrate that this liposome-based protein-in-adjuvant formulation is capable of inducing robust antibody and CD8+ T-cell responses that strongly inhibit parasite infection and development of liver stages, conferring durable sterilizing immunity. These findings underscore the potential of liposome-based adjuvants for inducing robust humoral and CD8+ T-cell responses and warrant further studies toward the development of novel subunit vaccine formulations with this adjuvant system.'

Additional information

Other mutants