A HOMOLOG OF THE CYSTEINE PROTEINASE GENE (ACP(1), OR EH-CPP3) OF PATHOGENIC ENTAMOEBA-HISTOLYTICA IS PRESENT IN NONPATHOGENIC E-DISPAR STRAINS

One of the three cysteine proteinase genes, ACP(1) (or CP 3), has been reported to be missing in non-pathogenic strains of Entamoeba histoly tica (or Entamoeba dispar as recently labeled). Unexpectedly, a gene f ragment very similar in its sequence (95% homology) to ACP(1) of patho genic strains was obtained by use of the polymerase chain reaction fro m genomic DNA and cDNA of various cloned non-pathogenic strains as wel l as in 23 clinical isolates from asymptomatic carriers. The finding o f the ACP(1) homologue in non-pathogenic or E. dispar strains rules ou t the proposed use of its absence for diagnostic purposes.