A reliable ex vivo invasion assay of human reticulocytes by Plasmodium vivax

The picture above shows ex vivo matured and concentrated P. vivax collected from a Burmese patient at Prof. Francois Nosten’s SMRU clinic, Mae Sod, Tak. Picture Taken by Bruce Russell 2011

Plasmodium vivax is the most important cause of malaria in Asia and South America, infecting more than 200 million people each year. There is no vaccine, and the vivax parasite is now resistant to many of the first line antimalarial drug treatments, such as chloroquine. Accentuating these problems is the fact that the vivax parasite is notoriously difficult to study, hampering efforts to develop effect control measures.

To remedy this situation clinicians from SMRU teamed up with the Singapore Immunology Network (part of the Agency for Science, Technology and Research (A*STAR)) to develop a powerful assay for testing vaccine candidates against the blood stage forms of the vivax malaria parasite. This method was validated by testing a leading vaccine candidate that targets the need for the P. vivax parasite to bind to a specific protein (called a “Duffy receptor”) in the human red blood cell before it can invade it. This study revealed that the effectiveness of such vaccines are significantly affected by genetic variation in the parasite. Four more vaccine candidates are currently being tested.

Bursting to get in! Minutes after the mature blood form of the vivax malaria parasite bursts from the human red blood cell it is ready to attach and invade young blood cells (stained light blue by Geimsa in the picture above).

See the paper