The use of proprietary tissue-culture media for the cultivation in vitro of the erythrocytic stages of Plasmodium knowlesi

Abstract

An improved perfusion apparatus for the cultivation of malaria parasites is described. It consists of a sandwich of three chambers, of which the outer two contained medium and the inner contained the infected blood sample.Using this apparatus and rocker-dilution cultures it has been shown that medium ‘199’ and medium ‘NCTC 135’ are as good as the Harvard medium for the cultivation of P. knowlesi in vitro.The asexual cycle of P. knowlesi took slightly longer in vitro than in vivo. The stage of development at which the parasite was inoculated into culture affected the amount of reinvasion of new host cells. Thus, a greater amount of re-invasion was obtained with an inoculum of schizonts than with one of ring stage parasites. The rate of multiplication of the parasite decreased at each successive subculture.I should like to thank Dr F. Hawking and Dr J. Williamson for their advice, Mr T. J. Scott-Finnigan for technical assistance, Mr F. R. Wanless and Mr C. D. Sutton for taking the photographs, and Mr F. A. New for drawing the figures. The perfusion apparatus was made by Mr T. Harding of the Engineering Division, National Institute for Medical Research. This work received financial assistance from the World Health Organization.