How Malaria Parasites Reduce the Deformability of Infected Red Blood Cells  S. Majid Hosseini, James J. Feng  Biophysical Journal  Volume 103, Issue 1, Pages 1-10 (July 2012) DOI: 10.1016/j.bpj.2012.05.026 Copyright © 2012 Biophysical Society Terms and Conditions

Figure 1 Discretization of a healthy RBC by SPH particles. The membrane is represented by elastic springs connecting neighboring particles into a more or less uniform network. The total number of particles in this case is 13,540. The arrows represent the stretching force applied by optical tweezers. Biophysical Journal 2012 103, 1-10DOI: (10.1016/j.bpj.2012.05.026) Copyright © 2012 Biophysical Society Terms and Conditions

Figure 2 Convergence test: steady stretching of the length (L) of a model RBC, relative to the undeformed length L0 = 2R0, as a function of the total number of SPH particles. The RBC contains no merozoites inside, and has a membrane shear modulus Gs = 15 μN/m and a bending modulus kb = 6 × 10−19 J. The stretching force F = 100 pN. Biophysical Journal 2012 103, 1-10DOI: (10.1016/j.bpj.2012.05.026) Copyright © 2012 Biophysical Society Terms and Conditions

Figure 3 Variation of the length (upper branch) and width (lower branch) of the healthy RBC with the stretching force. The results of our numerical simulation are compared with experimental data (1) and prior computations of Imai et al. (12) and Fedosov et al. (3). Biophysical Journal 2012 103, 1-10DOI: (10.1016/j.bpj.2012.05.026) Copyright © 2012 Biophysical Society Terms and Conditions

Figure 4 Variation of the length and width of the iRBC as a function of the stretching force in the ring stage. The solid curves are computation at Gs = 15 μN/m without any merozoites. The error bars on the computed result at 150 pN indicate variations due to inclusion of a disk-shaped merozoite in different sizes and configurations. The experimental data of Suresh et al. (1) are also plotted for comparison. Biophysical Journal 2012 103, 1-10DOI: (10.1016/j.bpj.2012.05.026) Copyright © 2012 Biophysical Society Terms and Conditions

Figure 5 Axisymmetric model for the trophozoite-stage iRBC, with a spherical merozoite located in the thicker part of the cell, centered at y = −1.65 μm. Biophysical Journal 2012 103, 1-10DOI: (10.1016/j.bpj.2012.05.026) Copyright © 2012 Biophysical Society Terms and Conditions

Figure 6 (a) Stretching of a trophozoite-stage iRBC, under a force of F = 150 pN, as a function of the membrane shear modulus Gs and the merozoite radius Rm. The horizontal plane is at 39% elongation, the experimentally observed amount. (b) The intersection of the 39%-elongation plane and the deformation surface, plotted on the (Gs, Rm) plane. Biophysical Journal 2012 103, 1-10DOI: (10.1016/j.bpj.2012.05.026) Copyright © 2012 Biophysical Society Terms and Conditions

Figure 7 Cross section of the oblate spheroid model for the schizont-stage iRBC. The parasite is represented by an oblate spheroid of the same aspect ratio as the whole cell. Biophysical Journal 2012 103, 1-10DOI: (10.1016/j.bpj.2012.05.026) Copyright © 2012 Biophysical Society Terms and Conditions

Figure 8 (a) Stretching of a schizont-stage iRBC, under a force of F = 100 pN, as a function of the membrane shear modulus Gs and the parasite/iRBC volume ratio υ. The horizontal plane is at 22% deformation, the experimentally observed amount. (b) The intersection of the 22%-deformation plane and the deformation surface, plotted on the (Gs, υ) plane. Biophysical Journal 2012 103, 1-10DOI: (10.1016/j.bpj.2012.05.026) Copyright © 2012 Biophysical Society Terms and Conditions

Figure 9 Symmetry plane of the stretched iRBC with a parasite having 60% of the total volume in the schizont stage (top), compared with that without the parasite (bottom). F = 100 pN and Gs = 15 μN/m in both cases. The length of the vectors indicates the local principal strain ϵ, the horizontal scale bar corresponding to ϵ = 1. Biophysical Journal 2012 103, 1-10DOI: (10.1016/j.bpj.2012.05.026) Copyright © 2012 Biophysical Society Terms and Conditions