Intervening Transcribed Spacer Region 1 Variability in Cyclospora cayetanensis

Abstract

ABSTRACT Cyclospora cayetanensis is an apicomplexan protozoan parasite which has emerged as an important cause of epidemic and endemic diarrhea. Water-borne as well as food-borne outbreaks have occurred, including a large number of U.S. cases associated with raspberries imported from Guatemala. Molecular markers exist for tracing the epidemiology of many of the bacterial pathogens associated with water-borne or food-borne diarrhea, such as serotyping and pulsed-field electrophoresis. However, there are currently no molecular markers available for C. cayetanensis . The intervening transcribed spacer (ITS) regions between the small- and large-subunit rRNA genes demonstrate much greater sequence variability than the small-subunit rRNA sequence itself and have been useful for the molecular typing of other organisms. Thus, ITS1 variability might allow the identification of different genotypes of C. cayetanensis . In order to determine the degree of ITS1 variability among C. cayetanensis isolates, the ITS1 sequences of C. cayetanensis isolates from a variety of sources, including raspberry-associated cases, cases from Guatemala, and pooled and individual isolates from Peru, were obtained. The ITS1 sequences of all five raspberry-associated isolates were identical, consistent with their origin from a single source. In contrast, one of the two Guatemala isolates and two Peruvian isolates contained multiple ITS1 sequences. These multiple sequences could represent multiple clones from a single clinical source or, more likely, variability of the ITS1 region within the genome of a single clone.