Cloning and expression of Sj423 gene encoding the egg-shell precursor protein of Schistosoma japonicum / 中国人兽共患病学报

The gene fragment encoding the egg-shell precursor protein of Schistosoma japonicum was amplified with RT-PCR by using PCR primer designed according to the 423 bp cDNA fragment of the Philippine strain of S.japonicum, the corresponding mDNA fragment of Chinese strain as template and then the 5' and 3' ends of this gene cDNA were amplified with 5' RACE and 3' RACE by using a series of primers designed according to the result of sequencing. Result of sequence analysis showed that this fragment, named as Sj423, contained a complete open reading frame (ORF) of gene encoding the egg-shell precursor protein of S.japonicum.(Chinese strain). As demonstrated by sequencing analysis. No intron could be detected in this gene fragment. This gene was subsequently expressed in E.coli after cloning into the expression vector pET28c(+). The molecular mass of the expressed product of this gene was 20.9 kDa as revealed by SDS-PAGE analysis, and Western blot analysis showed that the recombinant protein expressed could react well with the rabbit antiserum against the worm antigen of S.japonicum;indicating the good antigenicity of this expressed product.

Screening of T7 phage-display cDNA library from liver of Microtus fortis with extracts of schistosomulum and characterization of the positive clones / 生物工程学报

Microtus fortis is naturally resisitent to Schistosoma japonicum. In order to find schistosome-resistence-related genes of Microtus fortis, a T7 phage-display cDNA library from liver of Microtus fortis was screened with the soluble lysate of schistosomula. The specific phages were enriched 375-fold after 3 rounds of biopanning. Ninety-two positive clones picked at random were sequenced and 19 ESTs including 6 unreported genes were obtained. Compared with the negative phage clone control, five positive clones, No.4 (GenBank Accession No.: EW968294), No.13 (GenBank Accession No.: EW968303), No.14 (GenBank Accession No.: EW968304), No.15 (GenBank Accession No.: EW968305) and No.18 (GenBank Accession No.: EW968308) could induce significantly higher schistosomula mortality rate when co-cultivated with schistosomula. According to the function analysis and the shistosomula-killing effect in vitro, the genes encoding CASP8 and FADD-like apoptosis regulator isoform protein, alpha-2-HS-glycoprotein, M4 protein, R3H domain (binds single-stranded nucleic acids) isoform 2 and 3 previously unreported proteins (No.14, No.15 and No.18) obtained here, were schistosomiasis-resistence-related genes of Microtus fortis.

Screening the target genes of Schistosoma japonicum related to the naturely resistance of Microtus fortis / 中国血吸虫病防治杂志

Objective To look for the genes of Schistosoma japonicum related to the Schistosoma-resistance of Microtus fortis.Methods The fresh sera of Microtus fortis were used to screen a T7 phage display cDNA library from worms of Schistosoma japonicum established in our lab.The positive clones were sequenced and functionally analysed through bioinformatics.Results The specific phages binding to the sera of Microtus fortis were enriched 857-fold after three rounds of biopanning,and 58 positive clones picked at random were sequenced and 10 ESTs were obtained.BLASTn results showed that 7 ESTs had 99%-100% similarity to the genes of Shistosoma japonicum reported in GenBank and 1 EST had 82% similarity to a zinc finger protein encoden gene from Pan troglodytes.The results of these ESTs function prediction indicated most of them were involved in the regulation of gene expresion of Schistosoma japonicum.Conclusions Several target genes of Schistosoma japonicum related to the Schistosoma-resistance of Microtus fortis are obtained and those would lay foundation to expatiate the native resistance mechnism of Microtus fortis to Schistosoma japonicum.