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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

Direct infection of humanized mice by selected P. falciparum SMG01.Humanized mice were injected intravenously with the ring stage parasites of the in vivo adapted K1 P. falciparum strain SMG01. Thin blood smear was made and stained with Giemsa. Representative ring stage parasites are shown at 48 h (A), 96 h (B) and 144 h (C) after infection. Quantification of parasitemia is presented in (D). Positive (+ve) reading means that the level of parasitemia was low but detectable when at least 1 parasite could be detected in 100 microscopic fields. The parasitemia versus human RBC percentage (huRBC%) is shown in (E), where the average parasitemia/huRBC% is 10.3% ± 2.4%.
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pone.0129825.g004: Direct infection of humanized mice by selected P. falciparum SMG01.Humanized mice were injected intravenously with the ring stage parasites of the in vivo adapted K1 P. falciparum strain SMG01. Thin blood smear was made and stained with Giemsa. Representative ring stage parasites are shown at 48 h (A), 96 h (B) and 144 h (C) after infection. Quantification of parasitemia is presented in (D). Positive (+ve) reading means that the level of parasitemia was low but detectable when at least 1 parasite could be detected in 100 microscopic fields. The parasitemia versus human RBC percentage (huRBC%) is shown in (E), where the average parasitemia/huRBC% is 10.3% ± 2.4%.

Mentions: We then examined whether SMG01 parasites can generate microscopy-detectable infection in humanized mice where human RBCs are generated de novo. Unlike the parental K1 strain, SMG01 ring stage parasites were detected for three cycles by Giemsa staining of blood smear (Fig 4A–4C). The parasitemia ranged between 0.13 and 0.25% at the first cycle of infection, fell between 0.08 and 0.15% at the second cycle, and dropped to barely detectable levels at the third cycle of infection (Fig 4D). The parasitemia (%) versus human RBC percentage (huRBC%) is shown in Fig 4E, where the parasitemia/huRBC% (i.e., the parasitemia with respect to human RBCs) is 10.3% ± 2.4%. The low level of parasitemia could be attributed to the fact that there were only 1.5 to 2.8% human RBCs in the circulation. As a result, short-lived free merozoites are probably cleared before they have a chance to invade another human RBC to sustain the infection. Nevertheless, these results show that human RBCs generated de novo in mice can be infected by a selected P. falciparum K1 SMG01 parasite for at least 3 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)

Direct infection of humanized mice by selected P. falciparum SMG01.Humanized mice were injected intravenously with the ring stage parasites of the in vivo adapted K1 P. falciparum strain SMG01. Thin blood smear was made and stained with Giemsa. Representative ring stage parasites are shown at 48 h (A), 96 h (B) and 144 h (C) after infection. Quantification of parasitemia is presented in (D). Positive (+ve) reading means that the level of parasitemia was low but detectable when at least 1 parasite could be detected in 100 microscopic fields. The parasitemia versus human RBC percentage (huRBC%) is shown in (E), where the average parasitemia/huRBC% is 10.3% ± 2.4%.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0129825.g004: Direct infection of humanized mice by selected P. falciparum SMG01.Humanized mice were injected intravenously with the ring stage parasites of the in vivo adapted K1 P. falciparum strain SMG01. Thin blood smear was made and stained with Giemsa. Representative ring stage parasites are shown at 48 h (A), 96 h (B) and 144 h (C) after infection. Quantification of parasitemia is presented in (D). Positive (+ve) reading means that the level of parasitemia was low but detectable when at least 1 parasite could be detected in 100 microscopic fields. The parasitemia versus human RBC percentage (huRBC%) is shown in (E), where the average parasitemia/huRBC% is 10.3% ± 2.4%.
Mentions: We then examined whether SMG01 parasites can generate microscopy-detectable infection in humanized mice where human RBCs are generated de novo. Unlike the parental K1 strain, SMG01 ring stage parasites were detected for three cycles by Giemsa staining of blood smear (Fig 4A–4C). The parasitemia ranged between 0.13 and 0.25% at the first cycle of infection, fell between 0.08 and 0.15% at the second cycle, and dropped to barely detectable levels at the third cycle of infection (Fig 4D). The parasitemia (%) versus human RBC percentage (huRBC%) is shown in Fig 4E, where the parasitemia/huRBC% (i.e., the parasitemia with respect to human RBCs) is 10.3% ± 2.4%. The low level of parasitemia could be attributed to the fact that there were only 1.5 to 2.8% human RBCs in the circulation. As a result, short-lived free merozoites are probably cleared before they have a chance to invade another human RBC to sustain the infection. Nevertheless, these results show that human RBCs generated de novo in mice can be infected by a selected P. falciparum K1 SMG01 parasite for at least 3 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