In-Depth Biological Alteration Analysis of Plasmodium Knowelsi-Infected Red Blood Cells Using A Non-Invasive Optical Imaging Technique

Abstract

Background Imaging techniques are commonly used for understanding disease mechanisms and their biological features in such a microenvironment of the cell. In recent work, the understanding of parasite biology of malaria Plasmodium knowlesi was compiled from functional in vitro and imaging analysis using serial block-face scanning electron microscopy (SEM). Sample fixation during SEM analysis possibly makes the parasite membrane destruction. Methods In this study, we used a non-invasive optical technique, tomography, to explore the biological changes during the development of infected red blood cells (RBCs) by P. knowlesi. The commercial common-path diffraction optical tomography was used to measure individual infected RBCs' three-dimensional refractive index tomogram without an additional dyeing agent. Results We simultaneously examined structural, chemical, and physical modification by a parasite inside of host RBCs. The results had similar patterns with previous studies using SEM and other parasites such as P. falciparum and Babesia. Interestingly we found that P. knowlesi did not use hemoglobin as much as P. falciparum as a source of nutrition. Conclusions This tomography technique opens new ways to study the pathophysiology of malaria parasites more efficiently and is considered a promising tool for studying each Plasmodium species more in-depth.