Characterization of Naegleria species by restriction endonuclease digestion of whole-cell DNA.

Whole-cell DNA in Naegleria spp. and two related genera was examined by restriction endonuclease digestion and fractionation of the fragments by agarose gel electrophoresis. Visual inspection of ethidium bromide-stained gels shows differences in banding pattern between N. fowleri, N. lovaniensis, N. gruberi, N. jadini, N. australiensis, Didasculus thorntoni and Willaertia magna, and between the two subspecies of N. australiensis. Even between strains belonging to the same species differences could be observed. Significant differences were seen between strains of N. fowleri according to the continent of origin, and a hypothesis on the ancestry and the dispersal of N. fowleri was deduced from it. A N. fowleri strain isolated from one of the very few cured human infections showed the most distinct pattern within the species. The considerable variation detected with serological and biochemical techniques between strains of N. australiensis as well as between strains of N. gruberi, was confirmed in the analysis of their whole-cell DNA. With this technique the existence of N. jadini, D. thorntoni, W. magna and two Naegleria strains as separate systematic entities is substantiated.