Analysis of protein variation in Plasmodium falciparum by two-dimensional gel electrophoresis.

The proteins of cultured isolates of Plasmodium falciparum have been labelled with [35S]methionine and then examined for variation between isolates by the two dimensional gel electrophoresis system of O'Farrell. A large number (ca. 100) of proteins have been characterised in terms of their isoelectric point and molecular weight, and thirty five proteins have been compared in all isolates. These comparisons have been used to examine two main questions, namely whether there is any evidence for sub-speciation between isolates from W. Africa and S.E. Asia and whether there is evidence for variation between isolates from a single region in Thailand. The results show that small amounts of P. falciparum are sufficient for the study of variation in many proteins and that considerable variation occurs. These results are compared with those obtained by other workers, using enzyme electrophoretic variation, and the relative merits of the two methods are considered.