Parasites Replicate Inside Human Cell Hosts 1

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Clare Harding

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These images are of the parasite Toxoplasma gondii infecting human cells. In humans, Toxoplasma infection can cause devastating brain inflammation in people without an immune system and can cause miscarriage. It does this by rapidly replicating inside human cells, eventually busting them and going on to infect further cells. Here, I have imaged heavily infected cells showing many parasites inside one human cell. In blue (image 1) or white (image 2) the nucleus (containing the DNA) of both the human cell and the parasites can be seen.

The skeleton of the human cell (in this case a protein called actin) can be seen in red, occasionally wrapping around the replicating parasites. Individual parasites, only about 0.005 mm long, are illuminated in yellow or magenta. In some of these parasites, Toxoplasma has been caught in act of building two daughters which will later burst out of the mother.