Identity of Naegleria strains isolated from organs of freshwater fishes

Eighteen Naegleria strains were isolated from organs of freshwater fishes b elonging to 5 species. Morphometric study allowed the separation of the Nae gleria strains from the non-vahlkampfiid amoeboflagellates, but was inadequ ate for species determination. Six strains, representatives of groups that had a slightly different cyst size, were selected and corresponding derived clones were subjected to sequence analysis and riboprinting restriction fr agment length polymorphism (RFLP)-PCR analysis of the small subunit (SSU) r RNA genes. One strain isolated from the brain of a fish with systemic infec tion was characterised by an intronless 2 kb long SSU rRNA gene and was ide ntified as N, australiensis. Another 5 strains had a 1.3 kb long group I in tron in their SSU rRNA gene and, based on the SSU rRNA sequences and ribopr ints, RFLP-PCR patterns appeared in phylogenetic trees to be closely relate d to Naegleria clarki.