RMgmDB - Rodent Malaria genetically modified Parasites

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Summary

RMgm-4180
Malaria parasiteP. berghei
Genotype
Transgene
Transgene not Plasmodium: puromycin-N-acetyltransferase (pac)
Promoter: Gene model: PBANKA_0711900; Gene model (P.falciparum): PF3D7_0818900; Gene product: heat shock protein 70 (HSP70)
3'UTR: Gene model: PBANKA_0711900; Gene product: heat shock protein 70 (HSP70)
Insertion locus: Gene model: PBANKA_0719300; Gene product: bifunctional dihydrofolate reductase-thymidylate synthase, putative (dhfr/ts)
Phenotype Asexual bloodstage;
Last modified: 30 June 2017, 18:33
  *RMgm-4180
Successful modificationThe parasite was generated by the genetic modification
The mutant contains the following genetic modification(s) Introduction of a transgene
Reference (PubMed-PMID number) Reference 1 (PMID number) : 28638105
MR4 number
Parent parasite used to introduce the genetic modification
Rodent Malaria ParasiteP. berghei
Parent strain/lineP. berghei ANKA
Name parent line/clone RMgm-166
Other information parent lineThis mutant expresses GFP under the 5'- and 3'-regulatory sequences of HSP70
The mutant parasite was generated by
Name PI/ResearcherSoga A, Fukumoto S
Name Group/DepartmentNational Research Center for Protozoan Diseases
Name InstituteObihiro University of Agriculture and Veterinary Medicine
CityInada-cho, Obihiro, Hokkaido
CountryJapan
Name of the mutant parasite
RMgm numberRMgm-4180
Principal nameHSP70-pac
Alternative name
Standardized name
Is the mutant parasite cloned after genetic modificationYes
Phenotype
Asexual blood stageMutant blood stages have decreased sensitivity to puromycin compared to wild type blood stages (see additional information)
Gametocyte/GameteNot tested
Fertilization and ookineteNot tested
OocystNot tested
SporozoiteNot tested
Liver stageNot tested
Additional remarks phenotype

Mutant/mutation
The mutant expresses puromycin-N-acetyltransferase (pac) under control of the 5'- and 3'-regulatory sequences of HSP70

Protein (function)
Puromycin-N-acetyltransferase (pac) can be isolated from Streptomyces alboniger and shows resistance to the aminonucleoside antibiotic, puromycin.
As puromycin is severely toxic to rodents and thus cannot be used for selection of P. berghei in vivo, a pac-puromycin system was developed based on a short-term in vitro culture method

Phenotype
Mutant blood stages have decreased sensitivity to puromycin compared to wild type blood stages (see additional information)

Additional information
Puromycin-N-acetyltransferase (pac) can be isolated from Streptomyces alboniger and shows resistance to the aminonucleoside antibiotic, puromycin.
As puromycin is severely toxic to rodents and thus cannot be used for selection of P. berghei in vivo, a pac-puromycin system was developed based on a short-term in vitro culture method.

Using parasites that express pac under control of the HSP70 promoter, evidence is presented for the following:
- IC50 values of wild type and HSP70-PAC were 0.17 ± 0.06 μM and 5.69 ± 0.70 μM (mean ± SD), respectively.
- IC90 values of wild type and the mutant parasites were 0.55 ± 0.14 μM and 9.39 ± 1.07 μM (mean ± SD), respectively.
- A puromycin concentration for drug selection in vitro was 1.0 μg/ml (1.8 μM).

Three in vitro selections were performed with puromycin after transfection (see below for details): the first after 2 days, the second after 8 days, and the third after 12 days. After the second selection, more than 99% of parasites were GFP-negative. The mutant ratio increased significantly from first to second selections, but there was no significant  difference between second and third selections. A typical transfectant line was also analyzed using flow cytometry. More than 99% of parasites were GFP- negative after the second selection

In conclusion: Pac can be used as  a (additional) selectable marker for genetic modification of P. berghei
However, to be able to use pac as a (additional) selectable marker for genetic modification of P. berghei multiple rounds of in vitro selection and in vivo (in mice) propagation are required to select for the desired mutants

Other mutants


  Transgene: Mutant parasite expressing a transgene
Type and details of transgene
Is the transgene Plasmodium derived Transgene: not Plasmodium
Transgene namepuromycin-N-acetyltransferase (pac)
Details of the genetic modification
Inducable system usedNo
Additional remarks inducable system
Type of plasmid/construct(Linear) plasmid double cross-over
PlasmoGEM (Sanger) construct/vector usedNo
Modified PlasmoGEM construct/vector usedNo
Plasmid/construct map
Plasmid/construct sequence
Restriction sites to linearize plasmid
Selectable marker used to select the mutant parasitepuromycin-N-acetyltransferase (pac)
Promoter of the selectable markerhsp70
Selection (positive) procedurepuromycin in vitro
Selection (negative) procedureNo
Additional remarks genetic modificationThe pac expression cassette (containing the pac gene under the 5'- and 3'-regulatory sequences of HSP70) was introduced in a locus of mutant RMgmDB-166 which contains a locus containing GFP under conontrol of the the 5'- and 3'-regulatory sequences of HSP70. Selection in vitro with puromycin selects for parasites in which the GFP expression cassette is replaced with the pac expression cassette by double cross-over integration (and loss of GFP expression)
Additional remarks selection procedureIn the first selection of double crossover homologous recombination experiments, 200 μl of infected blood was collected in 5 ml of culture medium by heart puncture under anesthesia, using a syringe containing heparin solution. After centrifugation at 500 × g for 8 min at RT, the supernatant was discarded. The blood was resuspended in 10.8 ml of culture medium. The suspension was put into a 25 cm2 flask (Thermo Fisher Scientific) with 1.2 ml of puromycin (10 μg/ml, diluted by culture medium) solution to make a final concentration of 1.0 μg/ml and a total volume of 12 ml. This suspension was then incubated for 20 h. After drug selection, the sample was centrifuged at 500 × g for 8 min at RT and resuspended in 100 μl of PBS. The suspension was injected intravenously into a naive ICR mouse. When parasitemia reached 0.5–3.0% (about 5 days post-injection), the selection procedure was repeated. In the 2nd and 3rd selection, about 7 μl of infected tail blood were collected in 0.5 ml of culture medium (described above) with 2 μl of heparin solution (143 units/ml), and centrifuged at 500 × g for 5 min at room temperature (RT). The supernatant was discarded and the parasites were resuspended in 0.5 ml of culture medium. The suspension (450 μl) was put into a 24-well plate (Thermo Fisher Scientific), and either 50 μl of either puromycin solution (10 μg/ml, diluted by culture medium; Wako, Osaka, Japan; stock: 50 mg/ml in distilled water) to a final concentration of 1.0 μg/ml (1.8 μM). The parasites were incubated for 20 h (36.5 °C, 5% CO2, 5% O2, 90% N2). After incubation, the parasites were separated by centrifuge at 500 × g for 5 min at RT, and resuspended in 100 μl of PBS. They were then injected intravenously into a naive ICR mouse.

Three selections were performed after transfection: the first after 2 days, the second after 8 days, and the third after 12 days. After the second selection, more than 99% of parasites were GFP-negative. The mutant ratio increased significantly from first to second selections, but there was no significant ifference between second and third selections. A typical transfectant line was also analyzed using flow cytometry. More than 99% of parasites were GFP- negative after the second selection
Other details transgene
Promoter
Gene Model of Parasite PBANKA_0711900
Gene Model P. falciparum ortholog PF3D7_0818900
Gene productheat shock protein 70
Gene product: Alternative nameHSP70
Primer information details of the primers used for amplification of the promoter sequence  Click to view information
Primer information details of the primers used for amplification of the promoter sequence  Click to hide information
Sequence Primer 1
Additional information primer 1
Sequence Primer 2
Additional information primer 2
3'-UTR
Gene Model of Parasite PBANKA_0711900
Gene productheat shock protein 70
Gene product: Alternative nameHSP70
Primer information details of the primers used for amplification the 3'-UTR sequences  Click to view information
Primer information details of the primers used for amplification the 3'-UTR sequences  Click to hide information
Sequence Primer 1
Additional information primer 1
Sequence Primer 2
Additional information primer 2
Insertion/Replacement locus
Replacement / InsertionInsertion locus
Gene Model of Parasite PBANKA_0719300
Gene productbifunctional dihydrofolate reductase-thymidylate synthase, putative
Gene product: Alternative namedhfr/ts
Primer information details of the primers used for amplification of the target sequences  Click to view information
Primer information details of the primers used for amplification of the target sequences  Click to hide information
Sequence Primer 1
Additional information primer 1
Sequence Primer 2
Additional information primer 2
Sequence Primer 3
Additional information primer 3
Sequence Primer 4
Additional information primer 4