Mutant/mutation
The mutant lacks expression of PSOP9 (putative secreted ookinete protein).

Protein (function)
Unknown. The protein is detected in a proteome analysis of ookinetes and contains a predicted signal sequence.

Phenotype
The phenotype anlyses indicate a role during the transition of ookinete to oocyst and oocyst development. The mutants produces significant reduced numbers of oocysts and in addition a significantly reduced numbers of salivary gland sporozoites. Oocysts formed are morphologically indistinguishable from wild type oocysts and produce up to 85% of the wt number of midgut sporozoites, which express circumsporozoite (CS) protein on their surface.  Sporozoites persist within oocysts at least until day 30 of infection, suggesting that their egress might be impaired. Midgut sporozoites were not infective to C57Bl/6 mice

Additional information
PSOP9 was detected by mass spectroscopy in all three invasive parasite stages, in P. berghei ABS (with low confidence), P. falciparum schizonts and merozoites and on the infected RBC membrane, in P. berghei ookinetes and in P. falciparum sporozoites (Florens et al., 2002; 2004; Hall et al., 2005; J. D. Raine unpubl. data).  However, its function in the ABS is clearly dispensable as KO parasites were readily obtained.

It has been reported that the P. falciparum ortholog,  PF08_0008,  is refractory to gene knockout attempts (Arumugam TU, 2011, Infect. Immun.; PMID: 21896773.