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De Novo Generated Human Red Blood Cells in Humanized Mice Support Plasmodium falciparum Infection.

Amaladoss A, Chen Q, Liu M, Dummler SK, Dao M, Suresh S, Chen J, Preiser PR - PLoS ONE (2015)

Bottom Line: The poor reconstitution is mainly the result of a deficiency of appropriate human cytokines that are necessary for the development and maintenance of these cell lineages.In vivo adaptation of K1 strain further improves the infection efficiency and parasites can be detected by microscopy for 3 cycles.The parasitemia ranges between 0.13 and 0.25% at the first cycle of infection, falls between 0.08 and 0.15% at the second cycle, and drops to barely detectable levels at the third cycle of infection.

View Article: PubMed Central - PubMed

Affiliation: Infectious Diseases Interdisciplinary Research Group, Singapore-Massachusetts Institute of Technology Alliance for Research and Technology, Singapore, 138602, Singapore.

ABSTRACT
Immunodeficient mouse-human chimeras provide a powerful approach to study host specific pathogens like Plasmodium (P.) falciparum that causes human malaria. Existing mouse models of P. falciparum infection require repeated injections of human red blood cells (RBCs). In addition, clodronate lipsomes and anti-neutrophil antibodies are injected to suppress the clearance of human RBCs by the residual immune system of the immunodeficient mice. Engraftment of NOD-scid Il2rg-/- mice with human hematopoietic stem cells leads to reconstitution of human immune cells. Although human B cell reconstitution is robust and T cell reconstitution is reasonable in the recipient mice, human RBC reconstitution is generally poor or undetectable. The poor reconstitution is mainly the result of a deficiency of appropriate human cytokines that are necessary for the development and maintenance of these cell lineages. Delivery of plasmid DNA encoding human erythropoietin and interleukin-3 into humanized mice by hydrodynamic tail-vein injection resulted in significantly enhanced reconstitution of erythrocytes. With this improved humanized mouse, here we show that P. falciparum infects de novo generated human RBCs, develops into schizonts and causes successive reinvasion. We also show that different parasite strains exhibit variation in their ability to infect these humanized mice. Parasites could be detected by nested PCR in the blood samples of humanized mice infected with P. falciparum K1 and HB3 strains for 3 cycles, whereas in other strains such as 3D7, DD2, 7G8, FCR3 and W2mef parasites could only be detected for 1 cycle. In vivo adaptation of K1 strain further improves the infection efficiency and parasites can be detected by microscopy for 3 cycles. The parasitemia ranges between 0.13 and 0.25% at the first cycle of infection, falls between 0.08 and 0.15% at the second cycle, and drops to barely detectable levels at the third cycle of infection. Compared to existing mouse models, our model generates human RBCs de novo and does not require the treatment of mice with immunomodulators.

No MeSH data available.


Related in: MedlinePlus

Infection of ex vivo cultured P. falciparum K1 strain in humanized mice.Humanized mice were infected with ex vivo cultured P. falciparum K1 ring stage parasites and the parasite PCR product (indicated by arrow) was determined using nested PCR at the indicated time points after parasite injection. 3 out of 4 mice (M1, M3 and M4) showed infected human RBCs until the 3rd cycle. Genomic DNA prepared from blood of an uninfected mouse was used as negative (-ve) control.
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pone.0129825.g003: Infection of ex vivo cultured P. falciparum K1 strain in humanized mice.Humanized mice were infected with ex vivo cultured P. falciparum K1 ring stage parasites and the parasite PCR product (indicated by arrow) was determined using nested PCR at the indicated time points after parasite injection. 3 out of 4 mice (M1, M3 and M4) showed infected human RBCs until the 3rd cycle. Genomic DNA prepared from blood of an uninfected mouse was used as negative (-ve) control.

Mentions: To identify a parasite strain that can infect humanized mice more efficiently, we screened various P. falciparum strains along with a knob-less clone of 3D7 (3D7KL) and KAHRP k/o parasites [19]. Ring stage parasites were prepared from ex vivo culture with 100 μl blood from humanized mice as described above. The level of parasitemia was considered low but detectable when at least 1 parasite could be detected in 100 microscopic fields. Humanized mice were injected intravenously with the culture containing the ring stage parasites and infection was analyzed at 48, 96 and 144 h after injection. Among the 9 strains tested, parasite PCR products for FCR3 and T994 strains were detected in blood samples taken immediately after injection but not after 48 h. Parasite PCR products for DD2, KAHRP k/o, 7G8, and W2mef strains were detected at 48 h after injection. Parasite PCR products for HB3, K1 and 3D7KL strains were detected at 96 h after injection. At 144 h after injection, parasite PCR products were detected in one of the two K1 and HB3 samples (Fig 3 and S4 Fig), suggesting that these parasites can infect humanized mice for three cycles.


De Novo Generated Human Red Blood Cells in Humanized Mice Support Plasmodium falciparum Infection.

Amaladoss A, Chen Q, Liu M, Dummler SK, Dao M, Suresh S, Chen J, Preiser PR - PLoS ONE (2015)

Infection of ex vivo cultured P. falciparum K1 strain in humanized mice.Humanized mice were infected with ex vivo cultured P. falciparum K1 ring stage parasites and the parasite PCR product (indicated by arrow) was determined using nested PCR at the indicated time points after parasite injection. 3 out of 4 mice (M1, M3 and M4) showed infected human RBCs until the 3rd cycle. Genomic DNA prepared from blood of an uninfected mouse was used as negative (-ve) control.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4476714&req=5

pone.0129825.g003: Infection of ex vivo cultured P. falciparum K1 strain in humanized mice.Humanized mice were infected with ex vivo cultured P. falciparum K1 ring stage parasites and the parasite PCR product (indicated by arrow) was determined using nested PCR at the indicated time points after parasite injection. 3 out of 4 mice (M1, M3 and M4) showed infected human RBCs until the 3rd cycle. Genomic DNA prepared from blood of an uninfected mouse was used as negative (-ve) control.
Mentions: To identify a parasite strain that can infect humanized mice more efficiently, we screened various P. falciparum strains along with a knob-less clone of 3D7 (3D7KL) and KAHRP k/o parasites [19]. Ring stage parasites were prepared from ex vivo culture with 100 μl blood from humanized mice as described above. The level of parasitemia was considered low but detectable when at least 1 parasite could be detected in 100 microscopic fields. Humanized mice were injected intravenously with the culture containing the ring stage parasites and infection was analyzed at 48, 96 and 144 h after injection. Among the 9 strains tested, parasite PCR products for FCR3 and T994 strains were detected in blood samples taken immediately after injection but not after 48 h. Parasite PCR products for DD2, KAHRP k/o, 7G8, and W2mef strains were detected at 48 h after injection. Parasite PCR products for HB3, K1 and 3D7KL strains were detected at 96 h after injection. At 144 h after injection, parasite PCR products were detected in one of the two K1 and HB3 samples (Fig 3 and S4 Fig), suggesting that these parasites can infect humanized mice for three cycles.

Bottom Line: The poor reconstitution is mainly the result of a deficiency of appropriate human cytokines that are necessary for the development and maintenance of these cell lineages.In vivo adaptation of K1 strain further improves the infection efficiency and parasites can be detected by microscopy for 3 cycles.The parasitemia ranges between 0.13 and 0.25% at the first cycle of infection, falls between 0.08 and 0.15% at the second cycle, and drops to barely detectable levels at the third cycle of infection.

View Article: PubMed Central - PubMed

Affiliation: Infectious Diseases Interdisciplinary Research Group, Singapore-Massachusetts Institute of Technology Alliance for Research and Technology, Singapore, 138602, Singapore.

ABSTRACT
Immunodeficient mouse-human chimeras provide a powerful approach to study host specific pathogens like Plasmodium (P.) falciparum that causes human malaria. Existing mouse models of P. falciparum infection require repeated injections of human red blood cells (RBCs). In addition, clodronate lipsomes and anti-neutrophil antibodies are injected to suppress the clearance of human RBCs by the residual immune system of the immunodeficient mice. Engraftment of NOD-scid Il2rg-/- mice with human hematopoietic stem cells leads to reconstitution of human immune cells. Although human B cell reconstitution is robust and T cell reconstitution is reasonable in the recipient mice, human RBC reconstitution is generally poor or undetectable. The poor reconstitution is mainly the result of a deficiency of appropriate human cytokines that are necessary for the development and maintenance of these cell lineages. Delivery of plasmid DNA encoding human erythropoietin and interleukin-3 into humanized mice by hydrodynamic tail-vein injection resulted in significantly enhanced reconstitution of erythrocytes. With this improved humanized mouse, here we show that P. falciparum infects de novo generated human RBCs, develops into schizonts and causes successive reinvasion. We also show that different parasite strains exhibit variation in their ability to infect these humanized mice. Parasites could be detected by nested PCR in the blood samples of humanized mice infected with P. falciparum K1 and HB3 strains for 3 cycles, whereas in other strains such as 3D7, DD2, 7G8, FCR3 and W2mef parasites could only be detected for 1 cycle. In vivo adaptation of K1 strain further improves the infection efficiency and parasites can be detected by microscopy for 3 cycles. The parasitemia ranges between 0.13 and 0.25% at the first cycle of infection, falls between 0.08 and 0.15% at the second cycle, and drops to barely detectable levels at the third cycle of infection. Compared to existing mouse models, our model generates human RBCs de novo and does not require the treatment of mice with immunomodulators.

No MeSH data available.


Related in: MedlinePlus