[Comparison of efficiency of Kato-Katz technique and PCR assay for detecting Clonorchis sinensis infection]

OBJECTIVE

To compare the performance of modified Kato-Katz thick smear method (KK method) and PCR assay in field detection of Clonorchis sinensis in human fecal samples, which provides insight into the selection of tools for detecting C. sinensis.

METHODS

Based on the epidemiological investigation of human C. sinensis infections in Tengxian County of Guangxi Zhuang Autonomous Region in 2016, a total of 133 fecal samples were randomly selected and stored at -20 ℃. All fecal samples were detected for C. sinensis infection using KK method and PCR assay, and the detection rate was compared between the two techniques. In addition, Kappa test was used to evaluate the consistency between the two methods.

RESULTS

Among all fecal samples, the overall detection rate of C. sinensis was 77.44% (103/133), and the detection rate was significantly higher by PCR assay (70.68%, 93/133) than by KK method (57.14%, 76/133) (χ² = 26.15, P < 0.01). There were 88.16% (67/76) of the microscopy-positive fecal samples positive for PCR assay, and 47.37% (27/57) of the microscopy-negative fecal samples positive for PCR assay. The detection rate of C. sinensis by PCR assay (94.74%, 18/19) was higher in fecal samples with EPG of > 1 000 than in samples with EPG of < 1 000 (85.96%, 49/57) (χ² = 1.05, P = 0.436). The consistency of the detection rate of C. sinensis was moderate between the KK method and PCR assay (Kappa = 0.73).

CONCLUSIONS

The detection rate of C. sinensis by PCR assay is significantly higher than by KK method. In low-endemic areas of C. sinensis infections, the combination of KK method and PCR assay is suggested, so as to improve the detection rate.

[Human thelaziasis callipaeda in Tongren area of Guizhou Province: a case report]

This paper reports a case of human thelaziasis callipaeda in Tongren area of Guizhou Province.

[Sequential analysis of genome of Thelazia callipaeda]

OBJECTIVE

To investigate the molecular characteristics of genome sequence of Thelazia callipaeda (T. cp).

METHODS

The obtained T. cp genome assembling data were annotated by using a combination of ab initio gene by softwares, GeneMark and GeneID, and the homology of the experimentally confirmed genes was predicted by software GeMoMa. The results were integrated by software EVM to predict all genes of genome. The obtained genes were annotated in the common public database and three dedicated databases (CAZyme, TCDB and PHI), respectively.

RESULTS

The Scaffolds and Contigs gene structure of T. cp genome (79.34 Mb) was analyzed, and a total of 6 333 genes were obtained. The sequence search was conducted in the public databases using BLASTx, of which 97.85% of the genes could be annotated. The genes annotated in the NR database were the most (98.69%), and those enriched in the KEGG pathway were the least (50.50%). The functional genes were blasted by KOG database and totally 4 517 genes were found. The three special databases (CAZyme, TCDB and PHI) were used to annotate all the genes, and 136, 139 and 1 498 genes were assigned respectively, and the number of genes in the PHI database was the largest. In the cytochrome proprietary database, 238 cytochrome P450 genes were predicted.

CONCLUSIONS

We have preliminarily revealed the T. cp genome structure characteristics and annotation information, and totally 6 333 genes are obtained.

[Observation on destroyed architecture of splenic lymphoid follicles in mice infected with Schistosoma japonicum by immunohistochemistry]

Objective To observe the destroyed architecture of splenic lymphoid follicles in mice infected with Schistosoma japonicum by immunohistochemistry. Methods The mice infected with S. japonicum (20 cercariae/mouse) for 8 weeks were sacrificed, and the splenic samples were paraffin embedded and sliced. The sections were first stained by hematoxylin and eosin to observe the massive structure of splenic lymphoid follicles, and then B cells, follicular dendritic cells (FDC) and germinal center cells were labeled with anti-B220, anti-CD21 or anti-Ki67 antibodies respectively by immunohistochemistry to observe the distribution of the specific cells of lymphoid follicles. Results The results of HE staining showed that the structure of lymphoid follicles in spleens of infected mice was blurred, the number and area of follicles were significantly reduced compared to those of the normal mice. The immunohistochemical staining showed that the splenic T/B lymphocyte segregation, FDC network and germinal centers of the infected mice all disappeared. Conclusion The structure of splenic lymphoid follicles in the mice infected with S. japonicum is obviously damaged.

[Progress and application of immunodiagnostic methods of giardiasis]

Giardia lamblia is an important intestinal protozoan which can cause diarrhea in humans. The detection of Giardia infection is performed through the detection methods of pathogen, immunoassay and molecular biology. Currently, the immunodiagnostic methods have good application and development prospect because of high sensitivity and specificity, simple and convenient, and time saving. In this article, we review the main progress and application of immunodiagnostic methods for Giardia infection.

[In vitro pro - angiogenic activity of Echinococcus granulosus hydatid cysts from experimentally infected mice]

OBJECTIVE

To preliminarily study the pro-angiogenic activity of Echinococcus granulosus hydatid cysts against human umbilical vein endothelial cells in vitro and the transcriptional level of potential pro-angiogenic factors.

METHODS

The hydatid cysts and protoscolex derived from experimentally infected mice were collected and cultured in vitro, then the human umbilical vein endothelial cells were stimulated by the supernatant and cyst fluid respectively, and the angiogenesis was observed and analyzed through a microscope and the angiogenesis mode of the software NIH Image J. Meanwhile, the mouse homologous proteins of matrix metalloproteinase-9 (MMP-9) and high mobility group box B1 (HMGB1) were identified in E. granulosus genome through sequence alignment, and their transcriptional levels in the cyst wall and protoscolex were analyzed.

RESULTS

The culture supernatant of hydatid cysts significantly promoted human umbilical vein endothelial cells into tubes (F = 73.03, P < 0.001), the transcriptions of MMP-9 and HMGB1 were detected in the cyst wall and protoscolex, and the transcriptional level of MMP-9 was higher in protoscolex (t = -11.65, P < 0.001), while the level of HMGB1 was higher in hydatid cysts (t = 6.43, P = 0.003).

CONCLUSIONS

Some parasite-derived pro-angiogenic molecules may exist in the supernatant of E. granulosus hydatid cysts, while further researches are required into their exact mechanisms.

[Cloning, fusion expression and identification of thioredoxin encoding gene from Toxoplasma gondii]

OBJECTIVE

To clone and express the thioredoxin (Trx) from RH strain tachyzoites of Toxoplasma gondii, establish the prokaryotic expression vector and purify the recombinant protein, then produce the polyclonal anti-Trx antibody in rabbits.

METHODS

Trx fragment was amplified by PCR and cloned into the pET-28a (+) vector, and the recombinant protein was induced with IPTG and purified by Ni-NTA affinity chromatography. The polyclonal antibody specificity was detected by Western blotting.

RESULTS

The trx gene was amplified from T. gondii cDNA by PCR. The recombinant plasmid trx/pET-28a (+) was usefully constructed, and the recombinant TRX protein was expressed and purified. The TRX polyclonal antibody was also obtained. The specific band of TRX was detected by Western blotting.

CONCLUSIONS

Western blotting can detect the specificity of polyclonal anti-Trx antibody, which will facilitate the biological functions of Trx.