Construction of a cDNA library for Sparganum mansoni and screening of diagnostic antigen cadidates / 中国血吸虫病防治杂志

Objective To construct a cDNA library of Sparganum mansoni and immunoscreen antigen candidates for immunodiagnosis of sparganosis mansoni. Methods Total RNA was extracted from S. mansoni, and reversely transcribed into cDNA, which was ligated into the phage vector. These recombinant vectors were packaged in vitro to construct the SMART cDNA library of S. mansoni. Then, the cDNA library was immunoscreened with sera from patients with sparganosis mansoni to yield positive clones. The inserted fragments of positive clones were sequenced and subjected to homology analyses, and the structure and functions of the coding proteins were predicted. Results The SMATR cDNA library of S. mansoni was successfully constructed. The titer of the cDNA library was 6.25 × 106 pfu/mL, with a recombinant efficiency of 100%, and the mean length of the inserted fragments in the library was larger than 1 100 bp. A total of 12 positive clones were obtained by immunoscreening, and were categorized into Sm-I (Sm60-1), Sm-II (Sm58-1), Sm-III (Sm20-1) and Sm-IV (Sm22-3), with 1 134, 1 063, 883 bp and 969 bp long inserted fragments. Their coding proteins were highly homologous with the Spirometra erinaceieuropaei antigenic polypeptide, cytoplasmic antigen, ribosomal protein S4-like protein and unnamed protein product, respectively. Conclusions A SMART cDNA library of S. mansoni has been successfully constructed and 4 categories of positive clones have been identified, which provides a basis for further studies on diagnostic antigens for sparganosis mansoni.

Preparation of multi-epitope recombinant diagnostic antigen of Mycobacterium tuberculosis / 生物工程学报

Multi-epitope recombinant diagnostic antigen (designated 'B102') of Mycobacterium tuberculosis (Mtb) was prepared and evaluated as a serological diagnostic antigen. With TRX at the N-terminal and His tag at the C-terminal, the multi-epitope Mtb recombinant diagnostic antigen including 11 predicted B-cell epitopes from 6 Mtb antigens (PstS1, ESAT6, CFP10, Ag85B, Ag85A and PPE54) was expressed in Escherichia coli BL21 (DE3) and purified by Ni²⁺-Chelating affinity and DEAE anion exchange chromatography. Based on the antigenicity of B102 confirmed in Western blotting analysis, we constructed and evaluated a double-antigen sandwich ELISA for diagnosis of Mtb infection. The protein B102 exists in the form of inclusion bodies, accounting for 31.25% of the total proteins of the bacteria. After purification and renaturation, protein B102 exists in soluble form with the concentration 3.124 mg/mL and the homogeneity 96.71%. WB analysis demonstrated that protein B102 could react with antibodies in Mtb positive serum. Using the novel antigen in ELISA, we tested 60 Mtb-related positive and negative serum; The results showed the sensitivity, specificity, positive and negative predictive values and coincidence rate of the detection method is 90.00%, 93.33%, 93.10%, 90.32% and 91.67%, respectively. The McNemer analysis suggested there was no statistical difference between the 'Gold standard' and the novel ELISA with kappa 0.833, which suggested the excellent consistency. By prokaryotic expression and chromatography purification, the multi-epitope recombinant antigen B102 was obtained with excellent antigenicity, which could be applied for Mtb-related serological detection.

Epidemic and research progress of babesiosis / 中国血吸虫病防治杂志

Babesiosis is an emerging parasitic disease, distributed globally in Europe, Asia, Africa, North and South America, and Australia, and the United States is still the country with the largest number of babesiosis cases reported. Babesiosis in China is mainly distributed in the northeast, followed by the southwest and other regions. As a new vector-borne infectious disease, babesiosis poses a serious threat to human health, and its research foundation is relatively weak, so it requires more attention and recognition. The research hot spots on babesiosis are screening of diagnostic antigens, and the mechanisms of Babesia and the hosts, co-infections between Babesia and other pathogens. The epidemic distribution, screening of diagnostic antigens, host immune response mechanism and co-infection of babesiosis in our country and abroad are reviewed in this paper.

Assessing and screening for T-cell epitopes from Mycobacterium tuberculosis RD2 proteins for the diagnosis of active tuberculosis

ABSTRACT The Region of D eletion 2 (RD2) of Mycobacterium tuberculosis encodes reserved antigens that contribute to bacterial virulence. Among these antigens, Rv1983, Rv1986, Rv1987, and Rv1989c have been shown to be immunodominant in infected cattle; however, their diagnostic utility has not been evaluated in humans.In this study, we screened 87 overlapping synthetic peptides encoded by five RD2 proteins for diagnosing tuberculosis epitopes in 50 active tuberculosis (TB) cases, 31 non-tuberculosis patients and 36 healthy individuals. A pool of promising epitopes was then assessed for their diagnostic value in 233 suspected TB patients using a whole blood IFN-γ release assay.Only 10 peptides were recognized by more than 10% of active tuberculosis patients. The IFN-γ release responses to Rv1986-P9, P15, P16, Rv1988-P4, P11, and Rv1987-P11 were significantly higher in the active TB group than in the control groups (p < 0.05). The whole blood IFN-γ release assay based on these epitopes yielded a sensitivity of 51% and a specificity of 85% in diagnosing active tuberculosis, and the corresponding results using the T-SPOT.TB assay were 76% and 75%, respectively.In conclusion, these results suggest that the six epitopes from the RD2 of M. tuberculosis have potential diagnostic value in TB.

Cloning,expression and immunity analysis of transketolase of Echinococcus granulosus / 中国血吸虫病防治杂志

Objective To obtain the prokaryotic expression of transketolase genes and analyze its value as a diagnostic anti-gen for echinococcosis.Methods TK gene was amplified by PCR and cloned into prokaryotic vector pMD19-EgTK,and then subcloned into the expression vector pET-28a.The target gene TK prokaryotic expression plasmid pET-28a was constructed and transferred into BL21. The purified protein was identified by SDS-PAGE and Western blotting. The blood samples of patients with cystic echinococcosis(CE group),alveolar echinococcosis(AE group)and healthy people(healthy group)were collected and detected by ELISA with the recombinant EgTK protein as a diagnostic antigen.Results The recombinant plasmid pET-28a (+)-EgTK was constructed successfully,and there was a band around 70 kDa by using Western blotting.ELISA showed that the difference among the 3 groups of sera reaction A450was significantly different(F=44.47,P<0.01),and the A450values of the CE group(1.46±0.41)and AE group(1.28±0.29)were higher than that of the healthy group(0.66 ± 0.23),but there was no significant difference between the former two.Conclusion The recombinant EgTK protein is better to distinguish the echinococ-cosis group and healthy group,but it can't do a differential diagnosis between CE and AE cases.

Preparetion and analysis on the immunogenicity of Echinococcus granulosus-specific diagnostic antigen Eg-07279 / 中国人兽共患病学报

We screened echinococcosis-specific diagnostic antigen and verified its immunogenicity.The sequencing data of Echinococcus granulosus released by the National Human Genome Research Center was analyzed.The bioinformaties method was used to screen out Eg-07279 antigen gene Eg-07279,which was not expressed in Echinococcus granulosus and highly expressed in the original metacercariae.After expression,the recombinant protein rEg-07279 was purified by affinity chromatography.The specific IgG level was detected in the recombinant protein immunized mice and the immunogenicity was verified by Western blot.The selected antigen molecule Eg-07279 was cloned,expressed and purified to obtain the recombinant protein.The results of ELISA showed that the specific IgG level of Eg-07279 (2.559±0.125) was significantly higher than that of the blank group (0.319 0±0.01),the difference was statistically significant (P＜0.01);the Western blot results showed that the recombinant plasmids could be recognized by the secondary infection of the protoscolex and the serum of the recombinant protein immunized group,while the serum of the blank control group was not recognized by the serum.In summary,the Eg07279 antigen of E.granulosus was obtained and it was proved that the recombinant protein has good immunogenicity and is a good diagnostic antigen candidate molecule.

Clinical Evaluation of Rapid Diagnostic Test Kit Using the Polysaccharide as a Genus-Specific Diagnostic Antigen for Leptospirosis in Korea, Bulgaria, and Argentina

Leptospirosis, a zoonotic disease that is caused by many serovars which are more than 200 in the world, is an emerging worldwide disease. Accurate and rapid diagnostic tests for leptospirosis are a critical step to diagnose the disease. There are some commercial kits available for diagnosis of leptospirosis, but the obscurity of a species- or genus-specific antigen of pathogenic Leptospira interrogans causes the reduced sensitivity and specificity. In this study, the polysaccharide derived from lipopolysaccharide (LPS) of nonpathogenic Leptospira biflexa serovar patoc was prepared, and the antigenicity was confirmed by immunoblot and enzyme linked immunosorbent assay (ELISA). The performance of the rapid diagnostic test (RDT) kit using the polysaccharide as a diagnostic antigen was evaluated in Korea, Bulgaria and Argentina. The sensitivity was 93.9%, 100%, and 81.0% and the specificity was 97.9%, 100%, and 95.4% in Korea (which is a rare region occurring with 2 serovars mostly), Bulgaria (epidemic region with 3 serovars chiefly) and Argentina (endemic region with 19 serovars mainly) respectively. These results indicate that this RDT is applicable for global diagnosis of leptospirosis. This rapid and effective diagnosis will be helpful for diagnosis and manage of leptospirosis to use and the polysaccharide of Leptospira may be called as genus specific antigen for diagnosis.

Clinical Evaluation of Rapid Diagnostic Test Kit Using the Polysaccharide as a Genus-Specific Diagnostic Antigen for Leptospirosis in Korea, Bulgaria, and Argentina

Leptospirosis, a zoonotic disease that is caused by many serovars which are more than 200 in the world, is an emerging worldwide disease. Accurate and rapid diagnostic tests for leptospirosis are a critical step to diagnose the disease. There are some commercial kits available for diagnosis of leptospirosis, but the obscurity of a species- or genus-specific antigen of pathogenic Leptospira interrogans causes the reduced sensitivity and specificity. In this study, the polysaccharide derived from lipopolysaccharide (LPS) of nonpathogenic Leptospira biflexa serovar patoc was prepared, and the antigenicity was confirmed by immunoblot and enzyme linked immunosorbent assay (ELISA). The performance of the rapid diagnostic test (RDT) kit using the polysaccharide as a diagnostic antigen was evaluated in Korea, Bulgaria and Argentina. The sensitivity was 93.9%, 100%, and 81.0% and the specificity was 97.9%, 100%, and 95.4% in Korea (which is a rare region occurring with 2 serovars mostly), Bulgaria (epidemic region with 3 serovars chiefly) and Argentina (endemic region with 19 serovars mainly) respectively. These results indicate that this RDT is applicable for global diagnosis of leptospirosis. This rapid and effective diagnosis will be helpful for diagnosis and manage of leptospirosis to use and the polysaccharide of Leptospira may be called as genus specific antigen for diagnosis.