Investigation Of Blastocystis Hominis Infection On Students From Guangxi Medical University And The Genotypes’Preliminary Study Of65Cases Of Isolated Strains

Objective To investigate the speciality of college students’infection and variability of Blastocystis hominis in Guangxi Medical University and analyse the genotype for offering basis to prevent the intestinal diseases triggered by B. hominis and research classification of B. hominis.Methods The college students of Guangxi Medical University were selected as the epidemiological investigation object with random sampling. Examinations were made by means of improved aether-amprodium sedimentation and microscopic examination. Isolates were separated from the B. hominis positive excrement. After culturing in vitro, the genetic DNA of B. hominis isolates were extracted. Then the isolates were genotyped by PCR using seven pairs of known sequenced-tagged site (STS) primers. To design PCR primers using elf-la conserved fragment and make DNA sequence analysis and homology comparison to the unknown genotype strain. Then use method of MEGA to construct phylogenetic tree.Results The average infection rate of B.hominis in Guangxi Medical University was14.93%. Han infection rate was13.48%and Zhuang was18.38%and the infection rate of other nationalities was17.24%. The rate of infection for grade group was13.19%up to16.28%. Male infection rate was14.74%while female infection rate was15.06%. Guangxi provincial sources students’ infection rate was15.06%while other province sources students’ infection rate was13.94%. Ampify the53human isolates genetic DNA by the PCR reaction and the results showed that there were5subtypes in all. Subtype1and subtype4which occupied7.55%were both4isolates.17isolates were subtype3which occupied32.08%, Only1isolate was subtype6and5isolates were subtype7which occupied9.43%.22of the isolates had no target strips which were thought as unknown genotype B.h. Using elf-1α conserved fragment primer to amplify the23unknown isolates (11isolates were from college students of Guangxi medical university,12isolates were from the south coast of Guangxi province) by PCR reaction. The results showed that there were15isolates which appeared target strips and the rest8isolates were negative to the elf-1α primer. Sequencing the elf-1α conserved DNA gene successfully and made homology comparison. The comparison results showed the gene of the unknown isolates had homology up to70%with the S strains. According to the phylogenetic tree, there was at least3or more different population among the total13isolates.Conclusion (1) The infection rate of B.h was on a high level for the college students in Guangxi medical university and there is possibility for "campus infected"; The Zhuang has a higher infection rate than the Han.(2) Simple subtype1, simple subtype3, simple subtype4, simple subtype6, and simple subtype7were the dominant types in the area and subtype3is the main subtype. And simple subtype7was the first discovery in Guangxi province.(3) There has unknown genetype B.h in Guangxi. Preliminary study has showed that they were relative species with the S strains. There are at least4different groups among them too.(4) Elf-1α can be used as another basis for classification of B.h; the elf-1α PCR primers we design independently can reveal B.h genetic differences of unknown B.h isolates; and it has application value in B.h taxonomy.