Mutant/mutation
The mutant expresses a hybrid protein of the ookinete surface proteins P25 of P. vivax (Pv25) and P25 of P. berghei. Pv25/Pb25 is under the control of the 5'-UTR and 3'-UTR regulatory regions p25 of P. berghei. The pv25/pb25 gene is introduced in the p25-p28 locus of P. berghei, thereby disrupting both p25 and p28 which encode two major ookinete surface proteins of P. berghei.
This mutant was generated using a construct that contains a 0.9 kb 5′ UTR of pb25, a truncated pv25 gene together with the GPI addition sequence of pb25, it's 3′ UTR and the entire (1.6 kb) intergenic region between pb25 and pb28 ORFs.

Protein (function)
P25 is one of two major surface proteins (P25 and P28) of the plasma membrane of ookinetes. The proteins are conserved between different Plasmodium species. The proteins are characterized by a secretory N-terminal signal sequence followed by three or four epidermal growth factor (EGF) domains and a glycosylphosphatidylinositol (GPI) anchor. Synthesis of both proteins begins between 0.5 and 2 h after the formation of the female gametes, and the proteins are still present in young oocysts. The paralogous genes encoding P25 and P28 are located next to each other in the genome in a head to tail organization. Antibodies against P25 prevent the formation of oocysts in the mosquito and thereby block transmission of the parasite.
Recombinant Histidine-tagged P25 of P. vivax (Pvs25) expressed in yeast (Pvs25H) has been tested in humans in phase I clinical trials and induces antibodies that blocked transmission significantly (up to 80% reduction in oocyst intensity and a 20–30% reduction in prevalence of infection).

Phenotype
Expression of Pv25/Pb25 (DR3) in female gametes, zygotes and ookinetes. The protein is located on the surface of ookinetes. The protein is evenly distributed over the ookinete surface.

Additional information
The transgenic parasites Pv25DR3 and Pv25DR (RMgm-122) have been used to develop assays to determine transmission blocking activity (TBA) of sera against P25 of P. vivax.. It was shown that oocyst development of the transgenic parasites is inhibited by monoclonal antibody against Pv25 with the same kinetics exhibited by wild type parasites when exposed to mouse monoclonal antibodies targeted to a paralogous protein P28. Human transmission-blocking sera from a clinical vaccine trial of Pv25 inhibited oocyst development of Pv25DR and Pv25DR3, whereas non-blocking sera did not. It was shown that  transmission-blocking activity can be determined in a simple assays of ookinete development in vitro, assays that obviate the need for mosquito colonies. These results demonstrate that transgenic rodent malarias expressing proteins from human Plasmodium species can be cheap, safe, and simple tools for testing TBA from sera.

Other mutants
RMgm-222: Another mutant expressing  P25 of P. vivax  (line Pv25DR). In this mutant the complete ORF of pv25 is expressed under the control of 5'-UTR and 3'-UTR regulatory sequences.  In this mutants the Pv25 protein is also located on the surface of ookinetes. In contrast to mutant Pv25DR3 described here, the protein is not evenly distributed over the ookinete surface, but is mainly located at one pole of the ookinete.
RMgm-273: A P. berghei transgenic mutant expressing P25 of P.falciparum.