Mutant/mutation
The mutant lacks expression of HscB and Mei2. It also expresses mCherry and luciferase under constitutive promoters. 

Protein (function)
HscB: 
HscB is a putative mitochondrial iron-sulfur (Fe-S) protein assembly chaperone HscB (heat shock cognate B). HscB belongs to the Hsp40 protein family, known as heat shock cognate B chaperones, and it operates in conjunction with an Hsp70 family member, HscA, for the assembly of Fe-S proteins. Fe-S proteins possess an iron sulfur cluster (ISC) as a cofactor, enabling efficient electron transport and involvement in various cellular redox reactions. Examples of Fe-S proteins include aconitase of the tricarboxylic acid (TCA) cycle and succinate dehydrogenase of the respiratory chain [40, 41]. In most eukaryotic cells, the biogenesis of ISCs and Fe-S proteins occurs within the mitochondria via the ISC pathway. Plasmodium parasites, however, possess an additional ISC biogenesis pathway in the apicoplast, a vestigial plastid resembling the chloroplast [43, 44]. This pathway is known as the sulfur mobilization (SUF) pathway and has been shown to be essential for asexual blood stage development. Conditional knockout experiments targeting SufS, the first enzyme in the
SUF pathway during oocyst development, resulted in impaired sporozoite formation, underscoring the significance of the SUF pathway in sporozoite development. It has been reported previously that the deletion of hscB in P. berghei parasites did not exhibit significant impairment during the mosquito stage development.
Mei2:
Mei2 is a member of the largest family of RNA binding proteins (RBPs) – those that contain a RNA recognition motif (RRM), a stretch of 70-90 amino acids that contain two consensus RNA-interacting motifs, RNP1 and RNP2. RRM-containing proteins are subdivided into ten separate families (RRM_1 thru RRM_10) based on shared amino acid identities between members of each family and Mei2 contains a C-terminal RRM_2, thought to be unique to fungi and plants. Plasmodium contains a single Mei2-like gene. 
See for detailed analyses RMgm-4937 for the phenotype of a mutant lacking expression of MEI2:
Normal blood stage and mosquito stage development. Normal infectivity of sporozoites to hepatocytes in vitro and in vivo. Mutant parasites lacking expression of MEI 2 develop into large, mature liver stages with extensive nuclear division and expression of merozoite specific proteins, such as msp1 and ama1. Most of the parasites arrest growth, however, just before the formation of infective merozoites. Only after infection of mice with high doses of sporozoites (2x10(5)) some of the mice (3 out of 10) developed blood infections with a greatly prolonged prepatent period (12-14 days).

Phenotype
The double knockout (dKO) mutant PbHscB-PbMei2 lacks expression of HscB and Mei2 (PF3D7_0623400, PBANKA_1122300). To generate this line, a marker-free PbHscB-KO line was generated using negative selection of blood stages of the HscB-KO line (RMgm-5640). Subsequently, the PlasmoGEM vector for PbMei2-KO (PbGEM-300555) was transfected into the marker-free PbHscB-KO schizonts. 
No significant difference in oocyst size was observed between WT, PbHscB-KO, PbMei2-KO and PbHscB-PbMei2-dKO lines at day 7 and day 14 post-feeding, indicating that both gene deletions are dispensable for oocyst development. This finding was supported when counting the number of sporozoites present in salivary glands at earlier (day 18 and 19 post-feeding) and later (day 24, 26, and 28 post-feeding) time points, which showed no significant difference among the WT and the three KO lines.
Mice infected with 100,000 sporozoites of PbHscB-PbMei2-dKO did not develop a blood stage infection (up to 41 days post-injection).
The phenotype of liver stages of PbHscB-PbMei2-dKO resembled that of PbHscB-KO (RMgm-5640), displaying a substantial reduction in size and slow growth towards 48- and 56-hours post-infection. PbHscB-PbMei2-dKO liver stages do not express MSP1 at 56 hpi. At 56 hpi the mitochondria exhibited abnormal accumulations, and the cytoplasmic mCherry signal revealed numerous vacuoles within the parasite. Mice infected with 100,000 sporozoites of PbHscB-PbMei2-dKO did not develop a blood stage infection (up to 41 days post-injection).

Additional information
Automated microscopy analysis revealed that PbHscB-KO parasites exhibited impaired growth at 24, 48 and 56 hpi, while PbHscB-PbMei2-dKO parasites showed an even more pronounced growth defect. PbHscB-KO parasites consistently showed a significant reduction in size at all time points. When both knockouts were combined in the PbHscB-PbMei2-dKO parasites, the phenotype resembled that of PbHscB-KO, displaying a substantial reduction in size and slow growth towards 48- and 56-hours post-infection. Since PbMei2-KO parasites appeared to grow to a normal size, as previously reported for P. yoelii Mei2-KOs, further investigation was conducted on the late liver stage. PbMei2-KO-infected cells were fixed at 56 hpi and stained for MSP1, which is expressed just prior to merozoite formation, and for mitochondria using anti-TgHsp70 antibodies to assess parasite fitness. While WT parasites displayed cytomere stages with the invaginated plasma membrane and a strong MSP1 signal, PbMei2-KO parasites showed neither plasma membrane invaginations nor distinct MSP1 signal. The mitochondria of liver stages of PbMei2-dKO and the double knockout PbHscB-PbMei2-dKO exhibited abnormal accumulations, and the cytoplasmic mCherry signal revealed numerous vacuoles within the parasite. Staining with the PVM marker UIS4 showed that PbMei2-KO parasites at 56 hpi had a corrupted PVM and an apparent leakage into the host cell cytosol was observed. After infection of mice with 100.000 sporozoites blood-stage parasitemia appeared with a 2–3 day delay in PbHscB-KO and a 5–6 day delay in PbMei2-KO sporozoite-injected mice. No breakthrough infections were observed in mice injected with PbHscB-PbMei2-dKO sporozoites for up to 41 days post-injection

Analysis of a mutant expressing a C-terminal GFP-tagged version of HscB (RMgm-5645) showed the following:
- Evidence for expression in asexual blood stages as shown by flow-cytometric analysis
- Expression in oocysts and in (maturing/mature) liver stages (at 48 and 56 hour after invasion of hepatocytes by sporozoites) where it co-localized with mitochondria (that were stained with the mitochondrial dye MitoView 650).

Other mutants