Abstract
INTRODUCTIONBlastocystis is an intestinal protozoan that may play a role in the pathogenicity of humans. This study aimed to (i) genetically characterize Blastocystis isolates obtained from human fecal samples and the water supply of the city of Uberaba, Minas Gerais, Brazil, and (ii) to verify the phylogenetic relationship between these isolates. METHODSBlastocystis species present in 26 fecal samples obtained from humans and animals from Uberaba were genetically characterized by polymerase chain reaction-restriction fragment length polymorphism and polymerase chain reaction-sequence-tagged sites. All amplicons were partially sequenced and/or defined according to the GenBank classification. RESULTS Polymerase chain reaction amplicons were generated from 21 human isolates and 18 water samples. The subtypes defined were ST1 (53.3%), ST3 (40.0%), and ST2 (6.7%) for human isolates; ST10 (100%) for bovine isolates; and ST5 (50.0%), ST1 (25%), and ST3 (25%) for pigs. Sequencing of polymerase chain reaction products showed a 98%-99% identity for the Blastocystis sequences deposited in GenBank, except for sequences from water samples that showed the identity of algae sequences. Phylogenetic analysis of Blastocystis sequences showed two distinct groups, one of which was principally formed by ST1, ST5, and ST10, and the other by isolates characterized as ST3 and ST7. Both clades showed human and animal sequences, reinforcing the notion that Blastocystis subtypes are not host-specific.CONCLUSIONS The data showed that Blastocystis subtypes circulating in Uberaba are ST1-ST3, ST5, and ST10, present in both humans and animals, demonstrating that the Blastocystis subtypes are not host-specific; that is, zoonotic transmission is possible.
Highlights
Blastocystis is an intestinal protozoan that may play a role in the pathogenicity of humans
Sequencing of polymerase chain reaction products showed a 98%–99% identity for the Blastocystis sequences deposited in GenBank, except for sequences from water samples that showed the identity of algae sequences
This study aimed to: (i) genetically characterize the isolates of Blastocystis species obtained from human fecal samples and water supply in the city of Uberaba, Minas Gerais (MG), Brazil, and (ii) verify the phylogenetic relationship between Blastocystis isolates from humans, pigs, cattle, and water, to define the epidemiological profile of the parasite in this region
Summary
Blastocystis is an intestinal protozoan that may play a role in the pathogenicity of humans. Phylogenetic analysis of Blastocystis sequences showed two distinct groups, one of which was principally formed by ST1, ST5, and ST10, and the other by isolates characterized as ST3 and ST7. Both clades showed human and animal sequences, reinforcing the notion that Blastocystis subtypes are not host-specific. The molecular characterization of Blastocystis isolates has been carried out using different techniques; the analysis of the small ribosomal subunit gene (SSU-rDNA) is the most commonly used method[7,8,9,10,11] These studies showed that Blastocystis has broad genetic diversity and is classified into 17 subtypes (ST1-ST1712). Other subtypes have been found in pets, livestock, and zoo animals[12]
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