Scientists Discover How Malaria Parasite Enters Red Blood Cells From Liver, Escapes Detection

Scientists have discovered how the Plasmodium falciparum malaria parasite evades the human immune system when traveling from the liver into red blood cells, according to a study published Aug. 3 in the online edition of Science, the Times of India reports (Sinha, Times of India, 8/8). The discovery could lead to the development of new means of keeping the parasite from spreading to red blood cells and causing them to burst (Jia, SciDev.Net, 8/4). P. falciparum passes from a mosquito's saliva into the bloodstream and then enters the liver, where it infects and destroys liver cells before re-entering the blood stream to infect and kill red blood cells. To monitor the movement of the parasite from the liver to the blood, Robert Menard from France's Institut Pasteur and colleagues used a laser scanning microscope to track parasites that had been genetically altered to emit a fluorescent green protein (Times of India, 8/8). The researchers also stained a mouse's blood vessels with a red fluorescent marker. The researchers were able to record microscopic images at one-second intervals that showed the parasite's journey (ANI/New Kerala, 8/5). The scientists found that the parasites kill the liver cells they inhabit, which then break off and pass through gaps in the walls of blood vessels in the liver (SciDev.Net, 8/4). The parasites are then able to escape being destroyed by white blood cells by cloaking themselves in a structure comprised of liver cell membrane, which blocks the dying liver cell from transmitting a chemical signal that would instruct white blood cells to ingest it (ANI/New Kerala, 8/5). The team has seen the same process in human liver cells in a lab, according to SciDev.Net (SciDev.Net, 8/4). The team plans to travel to India in October to work with scientists from the International Centre for Genetic Engineering and Biotechnology in New Delhi to further study how the process occurs in humans. The scientists aim to find a way for human cells to detect and destroy the malaria parasites even when they are using the cloaking mechanism (Times of India, 8/8).