GENETIC-EVIDENCE FOR LATENT SEPTATA-INTESTINALIS INFECTION IN HUMAN IMMUNODEFICIENCY VIRUS-INFECTED PATIENTS WITH INTESTINAL MICROSPORIDIOSIS

Sequence data of the small subunit rRNA (SSU-rRNA) gene were used to i dentify Septata intestinalis in biopsies of human immunodeficiency vir us-infected patients by polymerase chain reaction (PCR), southern blot hybridization, cloning, and comparative genetic sequencing, DNA produ cts of correct size could be amplified from all examined tissues with S, intestinalis infection but also from 2 biopsies with Enterocytozoon bieneusi and from 1 biopsy with Encephalitozoon cuniculi infection. S outhern blot hybridization with an S. intestinalis-specific probe and partial sequencing of the DNA fragments showed high homology with publ ished S. intestinalis sequences and confirmed that the amplified PCR p roducts really derived from the SSU-rRNA gene of S, intestinalis, PCR testing can detect very light infections with S. intestinalis. Thus, S , intestinalis seems to occur more frequently in the form of latent in fections and the true prevalence of the parasites may be much higher t han previously reported.