Isolation,identification,and pathogenicity of Blastocystis sp

Abstract:

Blastocystis sp.is a widespread unicellular protozoan mainly parasitizing the intestines of humans and animals.This parasite has rich genetic diversity,with 42 subtypes (ST1–ST17,ST21,ST23–ST46) reported,of which ST1,ST2,and ST3 are prevalent.However,the pathogenicity levels and the pathogenicity differences among different subtypes have been controversial.[Objective] To determine the pathogenicity of ST1,ST2,and ST3 and explore whether there are differences in the pathogenicity between the three subtypes of Blastocystis sp.[Methods] Blastocystis sp.strains were isolated from fresh human and macaque faeces and identified by morphological observation,18S rRNA gene amplification and sequencing,and cluster analysis.After BALB/c mice were infected with strains of ST1,ST2,and ST3,the distribution characteristics of the parasites in vivo were observed.In addition,the clinical signs,weight gain,feed conversion rate,and mortality of the infected mice were recorded to compare the pathogenicity of the three subtypes.Finally,the pathological changes in the intestines of mice were observed.[Results] Three subtypes of Blastocystis sp.,ST1,ST2 and ST3,were successfully isolated and identified.Animal challenge results showed that the parasites predominantly colonized the intestine and negatively affected the health of mice.A high dose of ST3 resulted in death in mice,while ST1,ST2,and low doses of ST3 did not affect the survival of mice.Blastocystis sp.damaged the intestinal tissue of challenged mice.[Conclusion]Blastocystis sp.causes harm to the host by damaging the intestine.The pathogenicity varies among different subtypes and ST3 has stronger pathogenicity.This study lays a foundation for further studying the pathogenicity mechanism and provides data for assessing the threat ofBlastocystis sp.to public health.

Key words:Blastocystis sp.;isolation and identification;pathogenicity;pathology