Parasitology Research

, Volume 118, Issue 2, pp 657–662 | Cite as

Unusual 18S rDNA of Acanthamoeba containing intron turned out to be a T5/T4 chimera

  • Daniele CorsaroEmail author
  • Danielle Venditti
Genetics, Evolution, and Phylogeny - Short Communication


The free-living amoebae of the genus Acanthamoeba are widely investigated for their diversity and evolution. Studies usually employ biomolecular methods targeting the 18S rRNA gene, assigning strains according to a well-established genotyping system. Strains from at least four genotypes contain introns in their rDNA. By retracing the evolutionary history of these introns within the amoebae, we found that the 18S rDNA of TUMSJ-341 strain (ATCC PRA-11), assigned to the genotype T5 (A. lenticulata), proved very unusual in our analyses, not corresponding to the characteristics of the group. The sequence contains a group I intron recovered only in A. lenticulata. At BLAST, however, the intron-less 18S rDNA of TUMSJ-341 does not match with T5 strains but shows some affinity with strains from genotype T4, suggesting a new genotype. Our accurate analysis of this sequence finally revealed a mixture of variable regions, showing that such discordant results are due to the insertion into the gene of a strain T5 of a DNA fragment containing hypervariable regions specific for a T4 strain. Data presented herein indicate that this sequence is probably a chimera.


Acanthamoeba T4 Acanthamoeba T5 Acanthamoeba lenticulata 18S rDNA genotypes Variable regions Chimeric sequences 


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Conflict of interest

The authors declare that there is no conflict of interest.


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© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.CHLAREASVandœuvre-lès-NancyFrance

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