Molecular characterization of Blastocystis isolates from birds by PCR with diagnostic primers and restriction fragment length polymorphism analysis of the small subunit ribosomal RNA gene.

Seven Blastocystis isolates from birds were genotyped by polymerase chain reaction (PCR) using diagnostic primers, and the homology among isolates was then confirmed by restriction fragment length polymorphism (RFLP) analysis of the small subunit ribosomal RNA gene. A zoonotic genotype, subtype 4, was detected in three isolates by PCR, but the RFLP profiles of these isolates differed from those of the subtype 4 reported previously from a human. None of the other four isolates were amplified with any subtype-specific primer sets, and the profiles of these isolates were different from any ribodemes of Blastocystis hominis reported previously. In the present study, the seven isolates from birds were classified into three genetically distinct genotypes. Therefore, birds appear to be infected with multiple genotypes. It is unclear whether the isolates examined in the present study are zoonotic or not. Therefore, it is important to determine the phylogenetic relationships between unknown genotypes from birds and the multiple genotypes of B. hominis.