IDENTIFICATION OF 2 GENETIC-MARKERS THAT DISTINGUISH PATHOGENIC AND NONPATHOGENIC STRAINS OF ACANTHAMOEBA SPP

Species-level identification of Acanthamoeba isolates is difficult and gives little or no indication of the isolate's pathogenicity. We iden tified two amplification-based genetic markers that were highly correl ated with pathogenicity in Acanthamoeba spp. One marker, designed to a mplify a 485-bp fragment of the small-subunit ribosomal RNA gene (ssrD NA), was preferentially amplified from the nonpathogenic strains; ampl ifications from the pathogenic strains yielded anomalous fragments of 650 and 900 bp. A second marker was developed on the basis of the anom alous 650-bp fragment. Primers to this sequence preferentially amplifi ed a noncoding locus (called Ac6) only from the pathogenic strains. Th ese two genetic markers may be useful for identification of pathogenic Acanthamoeba spp. strains.