Homology of 18S small subunit ribosomal RNA gene among species and strains of Schistosoma and sensitivity of PCR assay to detect single cercaria / 中国血吸虫病防治杂志

ABSTRACT

Objective To research the homology of 18S small subunit ribosomal RNA(18S-rRNA) gene about Chinese Mainland and Philippine strains of Schistosoma japonicum,and Schistosoma mansoni,and the possibility to establish the PCR assay based on the gene for detecting the cercaria in a low density level. Methods The genomic DNAs of Chinese Mainland and Philippine strains of S.japonicum,and S.mansoni were extracted. The PCR assay was used to detect the identical target DNA elements in the above genome team and the homology of their genes was compared. The single cercaria was respectively treated with the method of heating in boiling water,the method of treating with ammonia and the method of treating with NaOH,HCl and ethanol,and the single treated cercaria and the single cercaria without treating were used as the templates to amplify the target DNA by using the PCR assay,and the detection rates of the PCR assay to detect the single cercaria treated with the different methods were calculated and compared. Results With the genomic DNAs of Chinese Mainland and Philippine strains of S.japonicum and S.mansoni as the templates,the target DNA element of which sequence length was 469 bp was all amplified by PCR. The target DNA was all amplified by PCR to the single cercaria treated with ammonia and the method of treating with NaOH,HCl and ethanol. However,only 50 percent of specimens of the single cercaria without treating and the single cercaria treated with the method of heating in boiling water were amplified to the target DNA by PCR. Conclusions The 18S-rRNA gene has the general homology among the species and strains of Schistosoma. The sensitivity of the PCR assay to detect the low density cercaria treated with ammonia or the method of treating with NaOH,HCl and ethanol is higher than that of the single cercaria without treating or treated with the method of heating in boiling water.