Unraveling the Variation Pattern of Oncomelania hupensis in the Yangtze River Economic Belt Based on Spatiotemporal Analysis.

The construction of the Yangtze River Economic Belt (YEB) is a great national economic development strategy in China. As the YEB covers most endemic provinces of schistosomiasis japonica featured by low endemicity, this study aimed to investigate the spatiotemporal distribution pattern of Oncomelania hupensis (O. hupensis), which serves as the only intermediate host of Schistosoma japonicum in the YEB. Annual data reflecting the distribution of O. hupensis from 2015 to 2021 were collected from the National Institute of Parasitic Disease, Chinese Center for Disease Control and Prevention. Spatial autocorrelation analysis, hotspot analysis and space-time scan analysis were performed to explore the aggregation features and spatiotemporal dynamics of the snail distribution. The distribution of both total snail habitats (during 2015-2021) and emerging snail habitats (in 2016, 2018 and 2020) showed spatial autocorrelation (Z = 15.8~16.1, p < 0.05; Z = 2.3~7.5, p < 0.05). Hotspot (high-value areas in space) counties were mainly clustered in the alluvial plain of the middle and lower reaches of the YEB. Eight spatial and temporal clusters of snail habitats were scanned and were mainly concentrated in the counties of Anhui, Jiangxi, Hubei, Hunan and Jiangsu provinces along the Yangtze River. The YEB carries a tremendous burden of O. hupensis. Surveillance and risk identification based on the snail presence should be strengthened to provide reference for protecting humans and public health security in the YEB.

The Current Distribution of Oncomelania hupensis Snails in the People's Republic of China Based on a Nationwide Survey.

Schistosomiasis is a helminth infection caused by the genus Schistosoma, which is still a threat in tropical and sub-tropical areas. In the China, schistosomiasis caused by Schistosoma japonicum is mainly endemic to the Yangtze River valley. The amphibious snail Oncomelania hupensis (O. hupensis) is the unique intermediate host of S. japonicum; hence, snail control is a crucial approach in the process of schistosomiasis transmission control and elimination. In 2016, a nationwide snail survey was conducted involving all snail habitats recorded since 1950 in all endemic counties of 12 provinces. A total of 53,254 existing snail habitats (ESHs) were identified, presenting three clusters in Sichuan Basin, Dongting Lake, and Poyang Lake. The overall habitat area was 5.24 billion m2, of which 3.58 billion m2 were inhabited by O. hupensis. The area inhabited by snails (AIS) in Dongting and Poyang Lakes accounted for 76.53% of the population in the country. Three typical landscape types (marshland and lakes, mountains and hills, and plain water networks) existed in endemic areas, and marshland and lakes had a predominant share (3.38 billion m2) of the AIS. Among the 12 endemic provinces, Hunan had a share of nearly 50% of AIS, whereas Guangdong had no ESH. Ditches, dryland, paddy fields, marshland, and ponds are common habitat types of the ESH. Although the AIS of the marshland type accounted for 87.22% of the population in the whole country, ditches were the most common type (35,025 or 65.77%) of habitat. Six categories of vegetation for ESHs were identified. A total of 39,139 habitats were covered with weeds, accounting for 55.26% of the coverage of the area. Multiple vegetation types of snail habitats appeared in the 11 provinces, but one or two of these were mainly dominant. Systematic sampling showed that the presence of living snails was 17.88% among the 13.5 million sampling frames. The occurrence varied significantly by landscape, environment, and vegetation type. The median density of living snails in habitats was 0.50 per frame (0.33 m × 0.33 m), and the highest density was 40.01 per frame. Furthermore, two main clusters with high snail densities and spatial correlations indicated by hotspot analysis were identified: one in Hunan and Hubei, the other in Sichuan. This national survey is the first full-scale census on the distribution of O. hupensis, which is significant, as transmission interruption and elimination are truly becoming the immediate goal of schistosomiasis control in China. The study discerns the detailed geographic distribution of O. hupensis with the hotspots of snail density in China. It is beneficial to understand the status of the snail population in order to finally formulate further national control planning.

Molecular Techniques as Alternatives of Diagnostic Tools in China as Schistosomiasis Moving towards Elimination.

Schistosomiasis japonica caused by the trematode flukes of Schistosoma japonicum was one of the most grievous infectious diseases in China in the mid-20th century, while its elimination has been placed on the agenda of the national strategic plan of healthy China 2030 after 70 years of continuous control campaigns. Diagnostic tools play a pivotal role in warfare against schistosomiasis but must adapt to the endemic status and objectives of activities. With the decrease of prevalence and infection intensity of schistosomiasis in human beings and livestock, optimal methodologies with high sensitivity and absolute specificity are needed for the detection of asymptomatic cases or light infections, as well as disease surveillance to verify elimination. In comparison with the parasitological methods with relatively low sensitivity and serological techniques lacking specificity, which both had been widely used in previous control stages, the molecular detection methods based on the amplification of promising genes of the schistosome genome may pick up the baton to assist the eventual aim of elimination. In this article, we reviewed the developed molecular methods for detecting S. japonicum infection and their application in schistosomiasis japonica diagnosis. Concurrently, we also analyzed the chances and challenges of molecular tools to the field application process in China.

Laboratory Evaluation of a Basic Recombinase Polymerase Amplification (RPA) Assay for Early Detection of Schistosoma japonicum.

Early detection of Schistosoma japonicum (S. japonicum) within its intermediate and definitive hosts is crucial for case finding and disease surveillance, especially in low-endemic areas. Recombinase polymerase amplification (RPA) has many advantages over traditional methods of DNA-amplification, such as polymerase chain reaction (PCR), including high sensitivity and specificity whilst being deployable in resource-poor schistosomiasis-endemic areas. Here, we evaluated the performance of a basic RPA assay targeting the 28srDNA gene fragment of S. japonicum (Sj28srDNA) using schistosome-infected Oncomelania hupensis (O. hupensis) and mouse models, compared to the traditional pathological method and a PCR assay. Overall S. japonicum infection prevalence within O. hupensis hosts by microscopic dissection, PCR and RPA was 9.29% (13/140), 32.14% (45/140) and 51.43% (72/140), respectively, presenting significant differences statistically (χ2 = 58.31, p < 0.001). It was noteworthy that infection prevalence by PCR and RPA performed was 34.44% (31/90) and 53.33% (48/90) in snails within 6 weeks post-infection, while the dissection method detected all samples as negatives. In addition, the basic RPA assay presented positive results from the fourth week post-infection and third day post-infection when detecting fecal DNA and serum DNA, respectively, which were extracted from a pooled sample from mice infected with 20 S. japonicum cercariae. This study suggests that the RPA assay has high potential for early detection of S. japonicum infection within its intermediate and definitive hosts.

Rapid Assessment on Potential Risks of Schistosomiasis Transmission - 7 PLADs, China, 2019 and 2021.

WHAT IS ALREADY KNOWN ABOUT THIS TOPIC?: Oncomelania hupensis(O. hupensis) and livestock are main infection sources of schistosomiasis. The schistosome infected O. hupensis and livestock's feces are important risk factors in the transmission of schistosomiasis. WHAT IS ADDED BY THIS REPORT?: The potential risks of schistosomiasis transmission remain prevalent, giving an early warning to local government with information on existing transmission risks. It is expected that the effectiveness and efficiency of schistosomiasis surveillance could be improved by conducting rapid risk assessment at the beginning of transmission season. WHAT ARE THE IMPLICATIONS FOR PUBLIC HEALTH PRACTICE?: Rapid risk assessment is essential in early detection and the active monitoring of indicators of the transmission risks of schistosomiasis in endemic areas. This could work synergistically with surveillance system to minimize infections and prevent rebounds of endemic schistosomiasis outbreaks.

A Carbon-Based DNA Framework Nano-Bio Interface for Biosensing with High Sensitivity and a High Signal-to-Noise Ratio.

Biosensing interface based on screen-printed carbon electrodes (SPCE) has been widely used for electrochemical biosensors in the field of medical diagnostics, food safety, and environmental monitoring. Nevertheless, SPCE always has a rough surface, which is easy to result in the disorder of nucleic acid capture probes, the nonspecific adsorption of signaling probes, the steric hindrance of target binding, and decrease in the signal-to-noise ratio and sensitivity of biosensors. So far, it still remains extremely challenging to develop high-efficiency carbon-based biosensing interfaces, especially for DNA probe-based assembly and functionalization. In this paper, we first used a specific DNA framework, DNA tetrahedron to solve the defects of the carbon interface, improving the biosensing ability of SPCE. With covalent coupling, the DNA tetrahedron could be immobilized on the carbon surface. Biosensing probe sequences extending from the DNA tetrahedron can be changed for different target molecules. We demonstrated that the improved SPCE could be applied for the detection of a variety of bioactive molecules. Typically, we designed gap hybridization, aptamer "sandwich" and aptamer competition reduction strategy for the detection of miRNA-141, thrombin, and ATP, respectively. High signal-to-noise ratio, sensitivity, and specificity were obtained for all of these kinds. Especially, the DNA tetrahedron-modified SPCE can work well with serum samples. The carbon-based DNA framework nano-bio interface would expand the use of SPCE and make electrochemical biosensors more available and valuable in clinical diagnosis.

DNA Framework-Supported Electrochemical Analysis of DNA Methylation for Prostate Cancers.

Epigenetic alterations hold great promise as biomarkers for early stage cancer diagnosis. Nevertheless, direct identification of rare methylated DNA in the genome remains challenging. Here, we report an ultrasensitive framework nucleic acid-based electrochemical sensor for quantitative and highly selective analysis of DNA methylation. Notably, we can detect 160 fg of methylated DNA in million-fold unmethylated DNA samples using this electrochemical methylation-specific polymerase chain reaction (E-MSP) method. The high sensitivity of E-MSP enables one-step detection of low-abundance methylation at two different genes in patient serum samples. By using a combination test with two methylation alterations, we achieve high accuracy and sensitivity for reliable differentiation of prostate cancer and benign prostate hypertrophy (BPH). This new method sheds new light on translational use in early cancer diagnosis and in monitoring patients' responses to therapeutic agents.

Contributions and achievements on schistosomiasis control and elimination in China by NIPD-CTDR.

Being a zoonotic parasitic disease, schistosomiasis was widely spread in 12 provinces of Southern China in the 1950s, severly harming human health and hindering economic development. The National Institute of Parasitic Diseases at the Chinese Center for Diseases Control and Prevention, and Chinese Center for Tropical Diseases Research (NIPD-CTDR), as the only professional institution focussing on parasitic diseases at the national level, has played an important role in schistosomiasis control in the country. In this article, we look back at the changes of schistosomiasis endemicity and the contribution of NIPD-CTDR to the national schistosomiasis control programme. We review NIPD-CTDR's activities, including field investigations, design of control strategies and measures, development of diagnostics and drugs, surveillance-response of endemic situation, and monitoring & evaluation of the programme. The NIPD-CTDR has mastered the transmission status of schistosomiasis, mapped the snail distribution, and explored strategies and measures suitable for different types of endemic areas in China. With a good understanding of the life cycle of Schistosoma japonicum and transmission patterns of the disease, advanced research carried out in the NIPD-CTDR based on genomics and modern technology has made it possible to explore highly efficient and soft therapeutic drugs and molluscicides, making it possible to develop new diagnostic tools and produce vaccine candidates. In the field, epidemiological studies, updated strategies and targeted intervention measures developed by scientists from the NIPD-CTDR have contributed significantly to the national schistosomiasis control programme. This all adds up to a strong foundation for eliminating schistosomiasis in China in the near future, and recommendations have been put forward how to reach this goal.

Ultrasensitive Electrochemical Biosensor of Bacterial 16S rRNA Gene Based on polyA DNA Probes.

Traditional microbiology analysis is usually hindered by the long time-cost and lack of portability in many urgent situations. In this work, we developed a novel electrochemical DNA biosensor (E-biosensor) for sensitive analysis of the 16S rRNA gene of five bacteria, using a consecutive adenine (polyA) probe. The polyA probe consists of a polyA tail and a recognition part. The polyA tail can combine onto the gold surface with improved controllability of the surface density, by conveniently changing the length of polyA. The recognition part of the capture probe together with two biotin-labeled reporter probes hybridize with the target DNA and form a stable DNA-tetramer sandwich structure, and then avidin-HRP enzyme was added to produce a redox current signal for the following electrochemical detection. Finally, we realized sensitive quantification of artificial target DNA with a limit of detection (LOD) of 10 fM, and excellent selectivity and reusability were also demonstrated. Importantly, the detection capability was equally good when facing bacterial genomic DNA, due to the base-stacking force of our multireporter-probe system, which can help to break the second structure and stabilize the probe-target complexes. Our biosensor was constructed on a 16-channel electrode chip without any polymerase chain reaction (PCR) process needed, which took a significant step toward a portable bacteria biosensor.

Contribution of Plasmodium immunomics: potential impact for serological testing and surveillance of malaria.

Introduction: Plasmodium vivax (Pv) and P. knowlesi account together for a considerable share of the global burden of malaria, along with P. falciparum (Pf). However, inaccurate diagnosis and undetectable asymptomatic/submicroscopic malaria infections remain very challenging. Blood-stage antigens involved in either invasion of red blood cells or sequestration/cytoadherence of parasitized erythrocytes have been immunomics-characterized, and are vital for the detection of malaria incidence. Areas covered: We review the recent advances in Plasmodium immunomics to discuss serological markers with potential for specific and sensitive diagnosis of malaria. Insights on alternative use of immunomics to assess malaria prevalence are also highlighted. Finally, we provide practical applications of serological markers as diagnostics, with an emphasis on dot immunogold filtration assay which holds promise for malaria diagnosis and epidemiological surveys. Expert commentary: The approach largely contributes to Pf and Pv research in identifying promising non-orthologous antigens able to detect malaria incidence and to differentiate between past and recent infections. However, further studies to profiling naturally acquired immune responses are expected in order to help discover/validate serological markers of no cross-seroreactivity and guide control interventions. More so, the application of immunomics to knowlesi infections would help validate the recently identified antigens and contribute to the discovery of additional biomarkers of exposure, immunity, or both.

Study roadmap for high-throughput development of easy to use and affordable biomarkers as diagnostics for tropical diseases: a focus on malaria and schistosomiasis.

BACKGROUND: Interventions are currently being used against 'infectious diseases of poverty', which remain highly debilitating and deadly in most endemic countries, especially malaria, schistosomiasis, echinococcosis and African sleeping sickness. However, major limitations of current 'traditional' methods for diagnosis are neither simple nor convenient for population surveillance, and showed low sensitivity and specificity. Access to novel technologies for the development of adequate and reliable tools are expressly needed. A collaborative project between African Network for Drugs and Diagnostics Innovation and partner institutions in Africa and China aims to screen suitable serological biomarkers for diagnostic pipelines against these 'diseases of the poor'. METHODS: Parasite-specific exposed versus unexposed individuals were screened and sera or urine/stools were collected through case-control studies in China and African countries. Target genes/open reading frames were selected, then will be cloned and cell-free expressed, quantified and immuno-detected. Target antigens/epitopes will be probed and screened with sera from exposed or unexposed individuals using a high-throughput antigen screening platform as the study progresses. The specificity and sensitivity of highly immunoreactive biomarkers will be evaluated as well, using enzyme-linked immunosorbent assays or dipsticks. DISCUSSION: This roadmap explicitly unfolds the integrated operating procedures with focus on malaria and schistosomiasis, for the identification of suitable biomarkers that will aid the prioritization of diagnostics for population use. However, there is need to further validate any new diagnostic through comparison with standard methods in field deployable tests for each region. Our expectations for the future are to seek regulatory approval and promote the use of diagnostics in endemic areas.

Improved chromatographic fingerprinting combined with multi-components quantitative analysis for quality evaluation of Penthorum chinense by UHPLC-DAD.

A high performance liquid chromatographic (HPLC) fingerprint is commonly used for quality consistency evaluation of herbal medicines. Recently, an improved chromatographic technique resulted in ultra high performance liquid chromatography (UHPLC), which could provide higher resolution in less time under higher pressure using finer particles (less than 2µm) of stationary phase. A simple and sensitive method was developed and validated for fingerprint analysis of Penthorum chinense Pursh (PC), with the simultaneous determination of seven components using UPLC coupled with a diode-array detector (DAD). It took less than 20 min for analysis of one sample. Both similarity analysis and principle components analysis (PCA) were employed to evaluate the quality consistency of 17 sample batches. The analysis was performed on a Waters ACQUITY UPLC HSS T3 (2.1 x 150 mm, 1.7 µm) column, which was maintained at 45°C and the eluents were monitored with DAD at 270 nm. A gradient elution with acetonitrile and water containing 0.075% phosphoric acid was used. The solvent flow rate was 0.4 mL/min. Standard calibration curves showed good linear behavior (R2 > 0.9994) in the range of 0.20-337.05 µg/mL. Acceptable repeatability (RSD < 0.61%), reproducibility (RSD < 2.72%), stability (RSD < 1.59%) and recovery in the range of 94.7%-102.9% were obtained (precision and accuracy). The validated method was successfully applied to evaluate the quality of 21 samples of PC.

A bubble-mediated intelligent microscale electrochemical device for single-step quantitative bioassays.

An intelligent microscale electrochemical device (iMED) for one-step, quantitative and multiplexed electrochemical detection of biomarkers for infectious diseases and tumors is developed. A "plug-in-cartridge" technology is introduced and adapted for use in screen-printed electrodes (SPEs) in electrochemical devices. Using this iMED, biomarkers for two types of tumors and one infectious disease are detected at sub-ng/mL levels in less than 30 min.

An integrated exact mass spectrometric strategy for comprehensive and rapid characterization of phenolic compounds in licorice.

RATIONALE: Licorice (Gancao) is derived from the dried roots and rhizomes of Glycyrrhiza species (Leguminosae) and appears as a component herb in about 60% of traditional Chinese medicine (TCM) prescriptions. Modern pharmacological studies have shown that flavonoids are one class of the major components responsible for the bioactivities of licorice. Ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC/QTOF MS) has proven to be a powerful tool for rapid profiling and identification of natural products in complex herbal medicines. METHODS: A UPLC/QTOF MS method was established for the first time for profiling and structural characterization of the phenolic compounds (most of them flavonoids) in licorice. The combined use of data-independent acquisition (MS(E) ) and data-dependent acquisition (DDA) was illustrated. RESULTS: Fifteen flavonoid reference compounds were used to explore the fragmentation pathways. Compound identification was based upon the exact mass, general fragmentation behaviors, retention times, UV absorption, and the related botanical biogenesis. As a result, a total of 51 compounds were characterized, three of which were reported for the first time. CONCLUSIONS: The LC/MS analysis for each injection took less than 9 min. The developed method is fast, accurate and reliable due to its high resolution and high efficiency characteristics as a result of combining both UPLC separation and QTOF exact mass measurement.

Diagnosis of schistosomiasis japonica with interfacial co-assembly-based multi-channel electrochemical immunosensor arrays.

Schistosomiasis control remains to be an important and challenging task in the world. However, lack of quick, simple, sensitive and specific sero-diagnostic test is still a hurdle in the control practice. The commonly employed enzyme-linked immuno-sorbent assay (ELISA) relies on the native soluble egg antigen (SEA) that is limited in supply. Here we developed an electrochemical immunosensor array (ECISA) assay with an interfacial co-assembly strategy. A recombinant Schistosoma japonicum (Sj) calcium-binding protein (SjE16) was used as a principal antigen, while the SEA as a minor, co-assembling agent, with a ratio of 8:1 (SjE16: SEA, Sj16EA), which was co-immobilized on a disposable 16-channel screen-printed carbon electrode array. A portable electrochemical detector was employed to detect antibodies in serum samples. The sensitivity of ECISA reached 100% with minimal cross-reactions. Therefore, we have demonstrated that this rapid, sensitive and specific ECISA technique has the potential to perform large-scale on-site screening of Sj infection.

[Cloning and expression of adenine phosphoribosyltransferase (APRT) and its differential expression analysis during the developmental stages of Schistosoma japonicum].

OBJECTIVE: To clone and express adenine phosphoribosyltransferase gene of Schistosoma japonicum, and analyze its stage-specific transcription and expression at different developmental stages of S. japonicum. METHODS: Specific primers were designed according to the reported EST sequence of SjAPRT1 gene (GenBank Accession No. AAW24796). RT-PCR was used to investigate the differential transcription of SjAPRT1 gene during the developmental stages. The gene was cloned into pET28a(+) plasmid. The recombinant plasmid rSjAPRT1/pET28a(+) was transformed into E. coli BL21(DE3) and induced with IPTG. The recombinant protein was purified with Ni-NTA resin and analyzed by SDS-PAGE. The purified protein was used to immune New Zealand white rabbits to obtain the antiserum. Western blotting was used to investigate the immunogenicity and the differential expression of rSjAPRT1 at different developmental stages. RESULTS: RT-PCR result showed that the specific bands were detected in eggs, cercariae, schistosomula, and adult worms (561 bp). Western blotting analysis showed that the recombinant protein (rSjAPRT1, about Mr 25 000) existed in eggs, schistosomula and adult worms. The recombinant protein was recognized by pooled sera of infected rabbits. CONCLUSION: The recombinant protein (rSjAPRT1) shows specific immunoreactivity, and is detected in the stage of eggs, schistosomula, and adult worms.

Carbon nanotube-based ultrasensitive multiplexing electrochemical immunosensor for cancer biomarkers.

A multiplexing electrochemical immunosensor was developed for ultrasensitive detection of cancer related protein biomarkers. We employed disposable screen-printed carbon electrode (SPCE) array as the detection platform. A universal multi-labeled nanoprobe was developed by loading HRP and goat-anti-rabbit IgG (secondary antibody, Ab(2)) onto multiwalled carbon nanotube (MWNT). This universal nanoprobe was available for virtually any sandwich-based antigen detection and showed superiority in several areas. By using the SPCE array and the universal nanoprobe, we could detect as low as 5 pg mL(-1) of prostate specific antigen (PSA) and 8 pg mL(-1) of Interleukin 8 (IL-8) with the electrochemical immunosensor. We also demonstrated simultaneous detection of two protein biomarkers with this platform. With these attracted features, our immunoassay system shows promising applications for in-field and point-of-care test in clinical diagnostics.

[Cloning, expression and identification of endothelial differentiation-related factor-1 gene of Schistosoma japonicum].

OBJECTIVE: To clone and express endothelial differentiation-related factor (SjEDF)-1 gene of Schistosoma japonicum, analyze its immunogenicity and the stage-specific expression at different developmental stages of S. japonicum. METHODS: Total RNA were extracted from eggs, cercariae, schistosomula and adult worms. The housekeeping gene SjActin was selected as the internal reference. According to the open reading frame for SjEDF-1 gene (GenBank accession number: AY336498), a pair of primers were designed to amplify the SjEDF-1 gene which was subcloned into pET-28a vector. The recombinant plasmid SjEDF-1/pET-28a was transformed into E. coli BL21 and induced with IPTG for expression. The recombinant protein was purified with Ni-NTA resin. The immune rabbit sera was prepared by immunizing New Zealand white rabbits with purified recombinant SjEDF-1 protein. Western blotting was used to analyze the immunogenicity and the expression level of SjEDF-1 at the different developmental stages. RESULTS: The SjEDF-1 gene was detected with a band of 405 bp in eggs, schistosomula, female and male worms. The recombinant protein (rSjEDF-I) was expressed as inclusion bodies (M, 20 000). Western blotting analysis showed that the purified rSjEDF-1 protein was recognized by pooled sera of infected rabbits. The target protein was detected only in schistosomulum and adult worms. CONCLUSION: The recombinant protein (rSjEDF-I) shows certain immunogenicity, and is detected only in schistosomula and adult worms.