| Successful modification | The parasite was generated by the genetic modification |
| The mutant contains the following genetic modification(s) |
Gene disruption
|
| Reference (PubMed-PMID number) |
Reference 1 (PMID number) : 19181869
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| MR4 number |
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| Parent parasite used to introduce the genetic modification |
| Rodent Malaria Parasite | P. berghei |
| Parent strain/line | P. berghei NK65 |
| Name parent line/clone |
Not applicable
|
| Other information parent line | A second mutant lacking expression of SIAP was generated in the P. berghei ANKA 507cl1 parent line. This parent line is a reference line of P.berghei ANKA that constitutively expresses GFP under control of the eukaryotic elongation factor-1a (eef1a) promoter of P. berghei (Janse et.al., (2006), Mol Biochemical Parasitology, 145: 60-70; see also RMgm-7). |
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| The mutant parasite was generated by |
| Name PI/Researcher | S. Engelmann, K. Matuschewski |
| Name Group/Department | Department of Parasitology |
| Name Institute | Heidelberg University School of Medicine |
| City | Heidelberg |
| Country | Germany |
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| Name of the mutant parasite |
| RMgm number | RMgm-233 |
| Principal name | siap-1(-) |
| Alternative name | |
| Standardized name | |
| Is the mutant parasite cloned after genetic modification | Yes |
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| Phenotype |
| Asexual blood stage | Not different from wild type |
| Gametocyte/Gamete | Not different from wild type |
| Fertilization and ookinete | Not different from wild type |
| Oocyst | Normal numbers of oocyst and oocyst-derived sporozoites are formed. In a significant fraction of mature oocysts the sporozoites did not egress from the oocysts resulting in reduced numbers of sporozoites in the hemocoel. |
| Sporozoite | Normal numbers of oocyst and oocyst-derived sporozoites are formed. In a significant fraction of mature oocysts the sporozoites did not egress from the oocysts resulting in reduced numbers of sporozoites in the hemocoel. No sporozoites were detected in the salivary glands. Sporozoites show infrequent, non-productive motility. |
| Liver stage | Mice/rats could not be infected by the bite of mosquitoes infected with the mutant.
Only by intravenous injections of high numbers of sporozoites (50.000), blood stage infections developed in mice. |
| Additional remarks phenotype | Mutant/mutation
The mutant lacks expression of SIAP-1 (Sporozoite Invasion-Associated Protein-1).
Protein (function)
SIAP-1 orthologs have been found exclusively in apicomplexan hemoprotozoa, parasites that are transmitted by arthropod vectors, e.g., Plasmodium, Babesia, and Theileria species (and is absent in, for example, Toxoplasma and Cryptosporidium). SIAP1 was first discovered in a systematic screen for P. falciparum sporozoite antigens recognized by sera from individuals that were immunized with irradiated sporozoites and termed antigen 17 (ag17). Subsequently, the P. yoelii ortholog was isolated in a suppression subtractive hybridization screen for genes that are specifically upregulated in sporozoites (S5) compared to blood stages. Analyses of a mutant expressing (C-terminal) mCherry-tagged form of SIAP-1 (RMgm-232). showed specific expression of SIAP-1 in sporozoites and liver stages.
Phenotype
The phenotype analyses indicate a partial defect in the egress of sporozoites from oocysts and indicate an additional effect on invasion of salivary glands. Sporozoites did not show gliding motility and a complete block of sporozoite transmission from highly infected mosquitoes was observed.
See also the phenotype analyses of mutant RMgm-109 which indicate that sporozoites lacking expression of SIAP-1are not affected in infectivity.
Additional information
See also Vignali, M. et al. (2009, Genome Biology, 10:216) for a discussion on the slightly different phenotypes reported for mutant RMgm-109 and RMgm-233, RMgm-234.
Other mutants
RMgm-109: A mutant lacking expression SIAP-1
RMgm-232: A mutant expressing (C-terminal) mCherry-tagged form of SIAP-1
RMgm-234: A mutant lacking expression SIAP-1 that expresses GFP under control of the sporozoite specific csp promoter. |
*RMgm-233
