Prevalence of glucose-6-phosphate dehydrogenase (G6PD) deficiency in Gia Lai Province, Vietnam

Glucose-6-phosphate dehydrogenase (G6PD; EC 1.1.1.49) deficiency is one of the most common X-linked hereditary disorders worldwide. G6PD deficiency provides resistance against severe malaria, but paradoxically, G6PD deficiency is also a stumbling block in fighting against malaria. Primaquine (PQ), a drug for the radical cure of Plasmodium vivax, can cause lethal acute hemolytic anemia in malaria patients with inherited G6PD deficiency. In this study, we analyzed the phenotypic and genotypic G6PD deficiency status in 1721 individuals (963 males and 758 females) residing in three malaria-endemic areas within the Gia Lai province, Vietnam. The G6PD activity in individuals ranged from 3.04 to 47.82 U/g Hb, with the adjusted male median (AMM) of 7.89 U/g Hb. Based on the G6PD activity assay results, no phenotypic G6PD deficiency was detected. However, the multiplex polymerase chain reaction to detect G6PD variations in the gene level revealed that 26 individuals (7 males, 19 females) had Viangchan mutations (871 G > A). Sequencing analyses suggested that all the males were hemizygous Viangchan, whereas one was homozygous, and 18 were heterozygous Viangchan in females. These results suggested a relatively low prevalence of G6PD deficiency mutation rate (1.51%) in the minor ethnic populations residing in the Gia Lai province, Vietnam. However, considering these areas are high-risk malaria endemic, concern for proper and safe use of PQ as a radical cure of malaria is needed by combining a G6PD deficiency test before PQ prescription.

(‒)-Epicatechin reveals amoebicidal activity against Acanthamoeba castellanii by activating the programmed cell death pathway

BACKGROUND

Acanthamoeba is an opportunistic pathogen that can cause human infections such as granulomatous amebic encephalitis and acanthamoeba keratitis. However, no specific drug to treat the diseases has been developed. Therefore, the discovery or development of novel drugs for treating Acanthamoeba infections is urgently needed. The anti-protozoan activity of (‒)-epicatechin (EC) has been reported, suggesting it is an attractive anti-protozoal drug candidate. In this study, the amoebicidal activity of EC against A. castellanii was assessed and its mechanism of action was unveiled.

METHODS

The amoebicidal activity of EC against A. castellanii trophozoites and the cytotoxicity of EC in HCE-2 and C6 cells were determined with cell viability assay. The underlying amoebicidal mechanism of EC against A. castellanii was analyzed by the apoptosis/necrosis assay, TUNEL assay, mitochondrial dysfunction assay, caspase-3 assay, and quantitative reverse transcription polymerase chain reaction. The cysticidal activity of EC was also investigated.

RESULTS

EC revealed amoebicidal activity against A. castellanii trophozoites with an IC50 of 37.01 ± 3.96 µM, but was not cytotoxic to HCE-2 or C6 cells. EC induced apoptotic events such as increases in DNA fragmentation and intracellular reactive oxygen species production in A. castellanii. EC also caused mitochondrial dysfunction in the amoebae, as evidenced by the loss of mitochondrial membrane potential and reductions in ATP production. Caspase-3 activity, autophagosome formation, and the expression levels of autophagy-related genes were also increased in EC-treated amoebae. EC led to the partial death of cysts and the inhibition of excystation.

CONCLUSION

EC revealed promising amoebicidal activity against A. castellanii trophozoites via programmed cell death events. EC could be a candidate drug or supplemental compound for treating Acanthamoeba infections.

Genetic Characterization and Phylogeographic Analysis of the First H13N6 Avian Influenza Virus Isolated from Vega Gull in South Korea

Avian influenza virus (AIV) is a pathogen with zoonotic and pandemic potential. Migratory birds are natural reservoirs of all known subtypes of AIVs, except for H17N10 and H18N11, and they have been implicated in previous highly pathogenic avian influenza outbreaks worldwide. This study identified and characterized the first isolate of the H13N6 subtype from a Vega gull (Larus vegae mongolicus) in South Korea. The amino acid sequence of hemagglutinin gene showed a low pathogenic AIV subtype and various amino acid substitutions were found in the sequence compared to the reference sequence and known H13 isolates. High sequence homology with other H13N6 isolates was found in HA, NA, PB1, and PA genes, but not for PB2, NP, M, and NS genes. Interestingly, various point amino acid mutations were found on all gene segments, and some are linked to an increased binding to human-type receptors, resistance to antivirals, and virulence. Evolutionary and phylogenetic analyses showed that all gene segments are gull-adapted, with a phylogeographic origin of mostly Eurasian, except for PB2, PA, and M. Findings from this study support the evidence that reassortment of AIVs continuously occurs in nature, and migratory birds are vital in the intercontinental spread of avian influenza viruses.

Genetic polymorphism and natural selection of the erythrocyte binding antigen 175 region II in Plasmodium falciparum populations from Myanmar and Vietnam

Plasmodium falciparum erythrocyte binding antigen 175 (PfEBA-175) plays essential role in erythrocyte invasion by the parasite and is a leading vaccine candidate. However, its genetic diversity in global isolates is a concern in developing an universal vaccine incorporating this protein. This study aimed to investigate genetic polymorphisms and natural selection of pfeba-175 region II (RII) in Myanmar and Vietnam P. falciparum isolates. Vietnam pfeba-175 RII displayed a low genetic polymorphism, while Myanmar pfeba-175 RII showed high levels of genetic diversity across the region. Point mutations, deletion, and recombinations were main factors contributing to genetic diversities in P. falciparum populations. Global pfeba-175 RII revealed similar, but not identical, genetic polymorphisms and natural selection profiles. Despite profiles of amino acid substitutions differed among populations, five major amino acid changes (K279E, E403K, K481I, Q584K, and R664) were commonly detected in global pfeba-175 RII populations. Haplotype network and genetic differentiation analyses of global pfeba-175 RII populations demonstrated no geographical relationships. Non-neglectable level of genetic diversity was observed in global pfeba-175 RII populations, emphasizing the need to consider this when designing an effective vaccine based on this protein. This study underscores the importance of the continuous monitoring of genetic diversity of pfeba-175 RII in the global P. falciparum populations.

Naegleria fowleri Extracellular Vesicles Induce Proinflammatory Immune Responses in BV-2 Microglial Cells

Extracellular vesicles (EVs) of protozoan parasites have diverse biological functions that are essential for parasite survival and host-parasite interactions. In this study, we characterized the functional properties of EVs from Naegleria fowleri, a pathogenic amoeba that causes a fatal brain infection called primary amoebic meningoencephalitis (PAM). N. fowleri EVs (NfEVs) have been shown to be internalized by host cells such as C6 glial cells and BV-2 microglial cells without causing direct cell death, indicating their potential roles in modulating host cell functions. NfEVs induced increased expression of proinflammatory cytokines and chemokines such as TNF-α, IL-1α, IL-1β, IL-6, IL-17, IFN-γ, MIP-1α, and MIP-2 in BV-2 microglial cells; these increases were initiated via MyD88-dependent TLR-2/TLR-4. The production levels of proinflammatory cytokines and chemokines in NfEVs-stimulated BV-2 microglial cells were effectively downregulated by inhibitors of MAPK, NF-κB, or JAK-STAT. Phosphorylation levels of JNK, p38, ERK, p65, JAK-1, and STAT3 were increased in NfEVs-stimulated BV-2 microglial cells but were effectively suppressed by each corresponding inhibitor. These results suggest that NfEVs could induce proinflammatory immune responses in BV-2 microglial cells via the NF-κB-dependent MAPK and JAK-STAT signaling pathways. Taken together, these findings suggest that NfEVs are pathogenic factors involved in the contact-independent pathogenic mechanisms of N. fowleri by inducing proinflammatory immune responses in BV-2 microglial cells, further contributing to deleterious inflammation in infected foci by activating subsequent inflammation cascades in other brain cells.

The Potential Breakthroughs with ChatGPT in Parasitology

The Article Abstract is not available.

Lipocalin-2 activates hepatic stellate cells and promotes nonalcoholic steatohepatitis in high-fat diet-fed Ob/Ob mice

BACKGROUND AND AIMS

In obesity and type 2 diabetes mellitus, leptin promotes insulin resistance and contributes to the progression of NASH via activation of hepatic stellate cells (HSCs). However, the pathogenic mechanisms that trigger HSC activation in leptin-deficient obesity are still unknown. This study aimed to determine how HSC-targeting lipocalin-2 (LCN2) mediates the transition from simple steatosis to NASH.

APPROACH AND RESULTS

Male wild-type (WT) and ob/ob mice were fed a high-fat diet (HFD) for 20 weeks to establish an animal model of NASH with fibrosis. Ob/ob mice were subject to caloric restriction or recombinant leptin treatment. Double knockout (DKO) mice lacking both leptin and lcn2 were also fed an HFD for 20 weeks. In addition, HFD-fed ob/ob mice were treated with gadolinium trichloride to deplete Kupffer cells. The LX-2 human HSCs and primary HSCs from ob/ob mice were used to investigate the effects of LCN2 on HSC activation. Serum and hepatic LCN2 expression levels were prominently increased in HFD-fed ob/ob mice compared with normal diet-fed ob/ob mice or HFD-fed WT mice, and these changes were closely linked to liver fibrosis and increased hepatic α-SMA/matrix metalloproteinase 9 (MMP9)/signal transducer and activator of transcription 3 (STAT3) protein levels. HFD-fed DKO mice showed a marked reduction of α-SMA protein compared with HFD-fed ob/ob mice. In particular, the colocalization of LCN2 and α-SMA was increased in HSCs from HFD-fed ob/ob mice. In primary HSCs from ob/ob mice, exogenous LCN2 treatment induced HSC activation and MMP9 secretion. By contrast, LCN2 receptor 24p3R deficiency or a STAT3 inhibitor reduced the activation and migration of primary HSCs.

CONCLUSIONS

LCN2 acts as a key mediator of HSC activation in leptin-deficient obesity via α-SMA/MMP9/STAT3 signaling, thereby exacerbating NASH.

Molecular Profiles of Multiple Antimalarial Drug Resistance Markers in Plasmodium falciparum and Plasmodium vivax in the Mandalay Region, Myanmar

Emergence and spreading of antimalarial drug resistant malaria parasites are great hurdles to combating malaria. Although approaches to investigate antimalarial drug resistance status in Myanmar malaria parasites have been made, more expanded studies are necessary to understand the nationwide aspect of antimalarial drug resistance. In the present study, molecular epidemiological analysis for antimalarial drug resistance genes in Plasmodium falciparum and P. vivax from the Mandalay region of Myanmar was performed. Blood samples were collected from patients infected with P. falciparum and P. vivax in four townships around the Mandalay region, Myanmar in 2015. Partial regions flanking major mutations in 11 antimalarial drug resistance genes, including seven genes (pfdhfr, pfdhps, pfmdr-1, pfcrt, pfk13, pfubp-1, and pfcytb) of P. falciparum and four genes (pvdhfr, pvdhps, pvmdr-1, and pvk12) of P. vivax were amplified, sequenced, and overall mutation patterns in these genes were analyzed. Substantial levels of mutations conferring antimalarial drug resistance were detected in both P. falciparum and P. vivax isolated in Mandalay region of Myanmar. Mutations associated with sulfadoxine-pyrimethamine resistance were found in pfdhfr, pfdhps, pvdhfr, and pvdhps of Myanmar P. falciparum and P. vivax with very high frequencies up to 90%. High or moderate levels of mutations were detected in genes such as pfmdr-1, pfcrt, and pvmdr-1 associated with chloroquine resistance. Meanwhile, low frequency mutations or none were found in pfk13, pfubp-1, pfcytb, and pvk12 of the parasites. Overall molecular profiles for antimalarial drug resistance genes in malaria parasites in the Mandalay region suggest that parasite populations in the region have substantial levels of mutations conferring antimalarial drug resistance. Continuous monitoring of mutations linked with antimalarial drug resistance is necessary to provide useful information for policymakers to plan for proper antimalarial drug regimens to control and eliminate malaria in the country.

Mapping of the Complement C9 Binding Region on Clonorchis sinensis Paramyosin

Heliminthic paramyosin is a multifunctional protein that not only acts as a structural protein in muscle layers but as an immune-modulatory molecule interacting with the host immune system. Previously, we found that paramyosin from Clonorchis sinensis (CsPmy) is bound to human complement C9 protein (C9). To analyze the C9 binding region on CsPmy, overlapping recombinant fragments of CsPmy were produced and their binding activity to human C9 was investigated. The fragmental expression of CsPmy and C9 binding assays revealed that the C9 binding region was located at the C-terminus of CsPmy. Further analysis of the C-terminus of CsPmy to narrow the C9 binding region on CsPmy indicated that the region flanking731Leu–780 Leu was a potent C9 binding region. The CsPmy fragments corresponding to the region effectively inhibited human C9 polymerization. These results provide a precise molecular basis for CsPmy as a potent immunomodulator to evade host immune defenses by inhibiting complement attack.

Biochemical Properties of Two Plasmodium malariae Cysteine Proteases, Malapain-2 and Malapain-4

Cysteine proteases belonging to the falcipain (FP) family play a pivotal role in the biology of malaria parasites and have been extensively investigated as potential antimalarial drug targets. Three paralogous FP-family cysteine proteases of Plasmodium malariae, termed malapains 2–4 (MP2–4), were identified in PlasmoDB. The three MPs share similar structural properties with the FP-2/FP-3 subfamily enzymes and exhibit a close phylogenetic lineage with vivapains (VXs) and knowpains (KPs), FP orthologues of P. vivax and P. knowlesi. Recombinant MP-2 and MP-4 were produced in a bacterial expression system, and their biochemical properties were characterized. Both recombinant MP-2 and MP-4 showed enzyme activity across a broad range of pH values with an optimum activity at pH 5.0 and relative stability at neutral pHs. Similar to the FP-2/FP-3 subfamily enzymes in other Plasmodium species, recombinant MP-2 and MP-4 effectively hydrolyzed hemoglobin at acidic pHs. They also degraded erythrocyte cytoskeletal proteins, such as spectrin and band 3, at a neutral pH. These results imply that MP-2 and MP-4 are redundant hemoglobinases of P. malariae and may also participate in merozoite egression by degrading erythrocyte cytoskeletal proteins. However, compared with other FP-2/FP-3 enzymes, MP-2 showed a strong preference for arginine at the P2 position. Meanwhile, MP-4 showed a primary preference for leucine at the P2 position but a partial preference for phenylalanine. These different substrate preferences of MPs underscore careful consideration in the design of optimized inhibitors targeting the FP-family cysteine proteases of human malaria parasites.

Sodium-bile acid co-transporter is crucial for survival of a carcinogenic liver fluke Clonorchis sinensis in the bile

The liver fluke Clonorchis sinensis inhabits the bile ducts, where bile concentration disparities across the fluke cell membrane can cause bile intoxication. Sodium-bile acid co-transporter (SBAT) plays a crucial role in bile acid recycling. The process by which SBAT imports bile acids is electrically coupled to sodium ion co-transportation. Here, we report that the SBAT of C. sinensis (CsSBAT) is involved in bile acid transportation. CsSBAT cDNA encoded a putative polypeptide of 546 amino acid residues. Furthermore, CsSBAT consisted of ten putative transmembrane domains, and its 3D structure was predicted to form panel and core domains. The CsSBAT had one bile acid- and three Na⁺-binding sites, enabling coordination of a symport process. CsSBAT was mainly localized in the mesenchymal tissue throughout the fluke body and sparsely localized in the basement of the tegument, intestinal epithelium, and excretory bladder wall. Bile acid permeated into the adult flukes in a short time and remained at a low concentration level. Bile acid accumulated inside the mesenchymal tissue when CsSBAT was inhibited using polyacrylic acid–tetradeoxycholic acid conjugate. The accumulated bile acid deteriorated the C. sinensis adults leading to death. CsSBAT silencing shortened the lifespan of the fluke when it was placed into bile. Taken together, we propose that CsSBAT transports bile acids in the mesenchymal tissue and coordinate with outward transporters to maintain bile acid homeostasis of C. sinensis adults, contributing to C. sinensis survival in the bile environment.

Clonorchiasis is a neglected tropical disease caused by infection with the liver fluke Clonorchis sinensis. C. sinensis is a biological carcinogen causing cholangiocarcinoma in humans. Juvenile worms inhabit and grow to adults in the bile ducts. Bile acids in the bile are double-edged molecules; they promote metabolism, but differences in their concentration across the cell membrane could lead to bile intoxication. The sodium-bile acid co-transporter of C. sinensis (CsSBAT) is indispensable for maintaining its normal physiology and bile detoxification in the bile duct. However, information related to the molecular and biological characteristics of the SBAT of liver flukes is not available. Here, we cloned CsSBAT for the first time in trematodes and characterized its tertiary structure and physiological functions. The sequential and structural properties of CsSBAT were similar to the apical sodium-bile acid co-transporter found in mammalian intestines. CsSBAT shared a mesenchymal tissue distribution with Na⁺-taurocholate co-transporting polypeptide in the hepatocytes adjacent to the bile ducts. Bile acids accumulated in C. sinensis adults when CsSBAT was inhibited, causing their death. This information might promote further studies on the physiological functions of SBAT and other trematode bile transporters and open new avenues toward developing novel anthelminthic drugs.

Genetic variations in histidine-rich protein 2 and histidine-rich protein 3 of Myanmar Plasmodium falciparum isolates

BACKGROUND

Malaria rapid diagnostic tests (RDTs) are precious tools to diagnose malaria. Most RDTs used currently are based on the detection of Plasmodium falciparum histidine-rich protein 2 (PfHRP2) in a patient's blood. However, concern has been raised in recent years that deletion of pfhrp2 in the parasite could affect the accuracy of PfHRP2-based RDTs. In addition, genetic variation in pfhrp2 might influence the accuracy and sensitivity of RDTs. In this study, the genetic variation in pfhrp2 and pfhrp3 in Myanmar P. falciparum isolates was analysed.

METHODS

Blood samples were collected from malaria patients who were infected with P. falciparum in Mandalay, Naung Cho, Tha Beik Kyin, and Pyin Oo Lwin, Upper Myanmar between 2013 and 2015. The pfhrp2 and pfhrp3 were amplified by nested polymerase chain reaction (PCR), cloned and sequenced. Genetic variation in Myanmar pfhrp2 and pfhrp3 was analysed using the DNASTAR program. Comparative analysis of Myanmar and global pfhrp2 and pfhrp3 isolates was also performed.

RESULTS

One-hundred and two pfhrp2 and 89 pfhrp3 were amplified from 105 blood samples, of which 84 pfhrp2 and 56 pfhrp3 sequences were obtained successfully. Myanmar pfhrp2 and pfhrp3 showed high levels of genetic variation with different arrangements of distinct repeat types, which further classified Myanmar pfhrp2 and pfhrp3 into 76 and 47 haplotypes, respectively. Novel amino acid changes were also found in Myanmar pfhrp2 and pfhrp3, but their frequencies were very low. Similar structural organization was shared by Myanmar and global pfhrp2 and pfhrp3, and differences in frequencies of repeat types and lengths were also observed between and among global isolates.

CONCLUSION

Length polymorphisms and amino acid substitutions generated extensive genetic variation in Myanmar pfhrp2 and pfhrp3. Comparative analysis revealed that global pfhrp2 and pfhrp3 share similar structural features, as well as extensive length polymorphisms and distinct organizations of repeat types. These results provide a better understanding of the genetic structure of pfhrp2 and pfhrp3 in global P. falciparum populations and suggest useful information to develop RDTs with improved quality.

Bile Ductal Transcriptome Identifies Key Pathways and Hub Genes in Clonorchis sinensis-Infected Sprague-Dawley Rats

Clonorchis sinensis is a food-borne trematode that infects more than 15 million people. The liver fluke causes clonorchiasis and chronical cholangitis, and promotes cholangiocarcinoma. The underlying molecular pathogenesis occurring in the bile duct by the infection is little known. In this study, transcriptome profile in the bile ducts infected with C. sinensis were analyzed using microarray methods. Differentially expressed genes (DEGs) were 1,563 and 1,457 at 2 and 4 weeks after infection. Majority of the DEGs were temporally dysregulated at 2 weeks, but 519 DEGs showed monotonically changing expression patterns that formed seven distinct expression profiles. Protein-protein interaction (PPI) analysis of the DEG products revealed 5 sub-networks and 10 key hub proteins while weighted co-expression network analysis (WGCNA)-derived gene-gene interaction exhibited 16 co-expression modules and 13 key hub genes. The DEGs were significantly enriched in 16 Kyoto Encyclopedia of Genes and Genomes pathways, which were related to original systems, cellular process, environmental information processing, and human diseases. This study uncovered a global picture of gene expression profiles in the bile ducts infected with C. sinensis, and provided a set of potent predictive biomarkers for early diagnosis of clonorchiasis.

Genetic diversity of Plasmodium vivax and Plasmodium falciparum lactate dehydrogenases in Myanmar isolates

Background

Plasmodium lactate dehydrogenase (pLDH) is a major target in diagnosing the erythrocytic stage of malaria parasites because it is highly expressed during blood-stage parasites and is distinguished from human LDH. Rapid diagnostic tests (RDTs) for malaria use pLDH as a target antigen; however, genetic variations in pLDH within the natural population threaten the efficacy of pLDH-based RDTs.

Methods

Genetic polymorphisms of Plasmodium vivax LDH (PvLDH) and Plasmodium falciparum LDH (PfLDH) in Myanmar isolates were analysed by nucleotide sequencing analysis. Genetic polymorphisms and the natural selection of PvLDH and PfLDH were analysed using DNASTAR, MEGA6, and DnaSP ver. 5.10.00 programs. The genetic diversity and natural selection of global PvLDH and PfLDH were also analysed. The haplotype network of global PvLDH and PfLDH was constructed using NETWORK ver. 5.0.0.3. Three-dimensional structures of PvLDH and PfLDH were built with YASARA Structure ver. 18.4.24 and the impact of mutations on structural change and stability was evaluated with SDM ver. 2, CUPSAT and MAESTROweb.

Results

Forty-nine PvLDH and 52 PfLDH sequences were obtained from Myanmar P. vivax and P. falciparum isolates. Non-synonymous nucleotide substitutions resulting in amino acid changes were identified in both Myanmar PvLDH and PfLDH. Amino acid changes were also identified in the global PvLDH and PfLDH populations, but they did not produce structural alterations in either protein. Low genetic diversity was observed in global PvLDH and PfLDH, which may be maintained by a strong purifying selection.

Conclusion

This study extends knowledge for genetic diversity and natural selection of global PvLDH and PfLDH. Although amino acid changes were observed in global PvLDH and PfLDH, they did not alter the conformational structures of the proteins. These suggest that PvLDH and PfLDH are genetically well-conserved in global populations, which indicates that they are suitable antigens for diagnostic purpose and attractive targets for drug development.

Fowlerstefin, a cysteine protease inhibitor of Naegleria fowleri, induces inflammatory responses in BV-2 microglial cells in vitro

Background

Naegleria fowleri is a free-living amoeba that causes an opportunistic fatal infection known as primary amoebic meningoencephalitis (PAM) in humans. Cysteine proteases produced by the amoeba may play critical roles in the pathogenesis of infection. In this study, a novel cysteine protease inhibitor of N. fowleri (fowlerstefin) was characterized to elucidate its biological function as an endogenous cysteine protease inhibitor of the parasite as well as a pathogenic molecule that induces immune responses in microglial cells.

Methods

Recombinant fowlerstefin was expressed in Escherichia coli. The inhibitory activity of fowlerstefin against several cysteine proteases, including human cathepsins B and L, papain and NfCPB-L, was analyzed. Fowlerstefin-induced pro-inflammatory response in BV-2 microglial cells was anayzed by cytokine array assay, reverse transcription polymerase chain reaction, and enzyme-linked immunosorbent assay.

Results

Fowlerstefin is a cysteine protease inhibitor with a monomeric structure, and belongs to the stefin family. Recombinant fowlerstefin effectively inhibited diverse cysteine proteases including cathepsin B-like cysteine proteases of N. fowleri (NfCPB-L), human cathepsins B and L, and papain. Expression of fowlerstefin in the amoeba was optimal during the trophozoite stage and gradually decreased in cysts. Fowlerstefin induced an inflammatory response in BV-2 microglial cells. Fowlerstefin induced the expression of several pro-inflammatory cytokines and chemokines including IL-6 and TNF in BV-2 microglial cells. Fowlerstefin-induced expression of IL-6 and TNF in BV-2 microglial cells was regulated by mitogen-activated protein kinase (MAPKs). The inflammatory response induced by fowlerstefin in BV-2 microglial cells was downregulated via inhibition of NF-κB and AP-1.

Conclusions

Fowlerstefin is a pathogenic molecule that stimulates BV-2 microglial cells to produce pro-inflammatory cytokines through NF-κB- and AP-1-dependent MAPK signaling pathways. Fowlerstefin-induced inflammatory cytokines exacerbate the inflammatory response in N. fowleri-infected areas and contribute to the pathogenesis of PAM.

Clonorchis sinensis MF6p/HDM (CsMF6p/HDM) induces pro-inflammatory immune response in RAW 264.7 macrophage cells via NF-κB-dependent MAPK pathways

Background

MF6p/host defense molecules (HDMs) are a broad family of small proteins secreted by helminth parasites. Although the physiological role of MF6p/HDMs in trematode parasites is not fully understood, their potential biological function in maintaining heme homeostasis and modulating host immune response has been proposed.

Methods

A gene encoding the MF6p/HDM of Clonorchis sinensis (CsMF6p/HDM) was cloned. Recombinant CsMF6p/HDM (rCsMF6p/HDM) was expressed in Escherichia coli. The biochemical and immunological properties of rCsMF6/HDM were analyzed. CsMF6p/HDM induced pro-inflammatory response in RAW 264.7 cells was analyzed by cytokine array assay, reverse transcription polymerase chain reaction, and enzyme-linked immunosorbent assay. The structural feature of CsMF6p/HDM was analyzed by three-dimensional modeling and molecular docking simulations.

Results

The CsMF6p/HDM shares a high level of amino acid sequence similarity with orthologs from other trematodes and is expressed in diverse developmental stages of the parasite. The rCsMF6p/HDM bound to bacteria-derived lipopolysaccharide (LPS), without effectively neutralizing LPS-induced inflammatory response in RAW 264.7 macrophage cells. Rather, the rCsMF6p/HDM induced pro-inflammatory immune response, which is characterized by the expression of TNF-α and IL-6, in RAW 264.7 cells. The rCsMF6p/HDM-induced pro-inflammatory immune response was regulated by JNK and p38 MAPKs, and was effectively down-regulated via inhibition of NF-κB. The structural analysis of CsMF6p/HDM and the docking simulation with LPS suggested insufficient capture of LPS by CsMF6p/HDM, which suggested that rCsMF6p/HDM could not effectively neutralize LPS-induced inflammatory response in RAW 264.7 cells.

Conclusions

Although rCsMF6p/HDM binds to LPS, the binding affinity may not be sufficient to maintain a stable complex of rCsMF6p/HDM and LPS. Moreover, the rCsMF6p/HDM-induced pro-inflammatory response is characterized by the release of IL-6 and TNF-α in RAW 264.7 macrophage cells. The pro-inflammatory response induced by rCsMF6p/HDM is mediated via NF-κB-dependent MAPK signaling pathway. These results collectively suggest that CsMF6p/HDM mediates C. sinensis-induced inflammation cascades that eventually lead to hepatobiliary diseases.

Genetic diversity and natural selection of transmission-blocking vaccine candidate antigens Pvs25 and Pvs28 in Plasmodium vivax Myanmar isolates

Transmission-blocking vaccines (TBVs) target the sexual stages of malarial parasites to interrupt or reduce the transmission cycle have been one of approaches to control malaria. Pvs25 and Pvs28 are the leading candidate antigens of TBVs against vivax malaria. In this study, genetic diversity and natural selection of the two TBV candidate genes in Plasmodium vivax Myanmar isolates were analyzed. The 62 Myanmar P. vivax isolates showed 9 and 19 different haplotypes for Pvs25 and Pvs28, respectively. The nucleotide diversity of Pvs28 was slightly higher than Pvs25, but not significant. Most amino acid substitutions observed in Myanmar Pvs25 and Pvs28 were concentrated at the EGF-2 and EGF-3 like domains. Major amino acid changes found in Myanmar Pvs25 and Pvs28 were similar to those reported in the global population, but novel amino acid substitutions were also identified. Negative selection was predicted in Myanmar Pvs25, whereas Pvs28 was under positive selection. Comparative analysis of global Pvs25 and Pvs28 suggests a substantial geographical difference between the Asian and American/African Pvs25 and Pvs28. The geographical genetic differentiation and the evidence for natural selection in global Pvs25 and Pvs28 suggest that the functional consequences of the observed polymorphism need to be considered for the development of effective TBVs based on the antigens.

Cytokine Production in Cholangiocarcinoma Cells in Response to Clonorchis sinensis Excretory-Secretory Products and Their Putative Protein Components

Clonorchis sinensis is a carcinogenic human liver fluke that promotes hepatic inflammatory environments via direct contact or through their excretory-secretory products (ESPs), subsequently leading to cholangitis, periductal fibrosis, liver cirrhosis, and even cholangiocarcinoma (CCA). This study was conducted to examine the host inflammatory responses to C. sinensis ESPs and their putative protein components selected from C. sinensis expressed sequenced tag (EST) pool databases, including TGF-β receptor interacting protein 1(CsTRIP1), legumain (CsLeg), and growth factor binding protein 2 (CsGrb2). Treatment of CCA cells (HuCCT1) with the ESPs or bacterial recombinant C. sinensis proteins differentially promoted the secretion of proinflammatory cytokines (IL-1β, IL-6, and TNF-α) as well as anti-inflammatory cytokines (IL-10, TGF-β1, and TGF-β2) in a time-dependent manner. In particular, recombinant C. sinensis protein treatment resulted in increase (at maximum) of ~7-fold in TGF-β1, ~30-fold in TGF-β2, and ~3-fold in TNF-α compared with the increase produced by ESPs, indicating that CsTrip1, CsLeg, and CsGrb2 function as strong inducers for secretion of these cytokines in host cells. These results suggest that C. sinensis ESPs contribute to the immunopathological response in host cells, leading to clonorchiasis-associated hepatobiliary abnormalities of greater severity.

Chemotactic migration of newly excysted juvenile Clonorchis sinensis is suppressed by neuro-antagonists

The metacercariae of the Clonorchis sinensis liver fluke excyst in the duodenum of mammalian hosts, and the newly excysted juveniles (CsNEJs) migrate along the bile duct via bile chemotaxis. Cholic acid is a major component of bile that induces this migration. We investigated the neuronal control of chemotactic behavior of CsNEJs toward cholic acid. The migration of CsNEJs was strongly inhibited at sub-micromolar concentration by dopamine D1 (LE-300 and SKF-83566), D2 (spiramide, nemonapride, and sulpiride), and D3 (GR-103691 and NGB-2904) receptor antagonists, as well as a dopamine reuptake inhibitor (BTCP). Neuropeptides, FMRFamide, peptide YY, and neuropeptide Y were also potent inhibitors of chemotaxis. Meanwhile, serotonergic, glutamatergic, and cholinergic inhibitors did not affect chemotaxis, with the exception of fluoxetine and CNQX. Confocal immunofluorescence analysis indicated that dopaminergic and cholinergic neurons were colocalized in the somatic muscle tissues of adult C. sinensis. Our findings suggest that dopaminergic neurons and neuropeptides play a major role in the chemotactic migration of CsNEJs to bile, and their inhibitors or modulators could be utilized to prevent their migration from the bile duct.

Tissue Fluid Enzyme-Linked Immunosorbant Assay for Piglets Experimentally Infected with Toxoplasma gondii and Survey on Local and Imported Pork in Korean Retail Meat Markets

To investigate the prevalence of Toxoplasma gondii in pork on the market in Korea, an in-house enzyme-linked immunosorbent assay for tissue fluid (CAU-tf-ELISA) was developed using a soluble extract of T. gondii RH strain tachyzoites. As the standard positive controls, the piglets were experimentally infected with T. gondii: Group A (1,000 cysts-containing bradyzoites), Group B (500 cysts-containing bradyzoites) and Group C (1.0×103 or 1.0×104 tachyzoites). The CAU-tf-ELISA demonstrated infection intensity-dependent positivity toward tissue fluids with average cut-off value 0.15: 100% for Group A, 93.8% for Group B and 40.6% for Group C. When tissue-specific cut-off values 0.066-0.199 were applied, CAU-tf-ELISA showed 96.7% sensitivity, 100% specificity, 100% positive and 90.0% negative predictive values. When compared with the same tissue fluids, performance of CAU-tf-ELISA was better than that of a commercial ELISA kit. Of the 583 Korea domestic pork samples tested, anti-T. gondii antibodies were detected from 9.1% of whole samples and 37.9% from skirt meat highest among pork parts. In the 386 imported frozen pork samples, 1.8% (skirt meat and shoulder blade) were positive for anti-T. gondii antibodies. In Korea, prevalence of anti-T. gondii antibodies in the pork on retail markets appeared high, suggesting that regulations on pig farming and facilities are necessary to supply safe pork on the tables.

Bile acids drive chemotaxis of Clonorchis sinensis juveniles to the bile duct

Clonorchiasis is a neglected tropical disease caused by Chinese liver fluke, Clonorchis sinensis infection. C. sinensis is a biological carcinogen causing cholangiocarcinoma in humans. In the mammalian host, C. sinensis newly excysted juveniles (CsNEJs) migrate from the duodenum into the bile duct. Bile drives the chemotactic behavior of CsNEJs. Little is known about which components of bile induce the chemotaxis. We designed a chemotaxis assay panel and measured the chemotactic behavior of CsNEJs in response to bile or bile acids. The CsNEJs migrated toward 0.1–1% bile but away from 5–10% bile. The CsNEJs showed strong chemoattraction to cholic acid ≥25 mM, but chemorepulsion to lithocholic acid ≥0.25 mM. To the CsNEJs, mixture of cholic acid and lithocholic acid was chemoattractive at a ratio greater than 25:1 but chemorepulsive at one smaller than that. Regarding migration in the mammalian hosts, high concentration of lithocholic acid in the gallbladder bile may repel CsNEJs from entering it. However, bile in the hepatic bile duct has a chemoattractive strength of cholic acid but a trace amount of lithocholic acid. Collectively, our results explain why the CsNEJs migrate principally to the hepatic bile ducts, bypassing the gallbladder.

We previously reported that Clonorchis sinensis newly excysted juveniles (CsNEJs) were chemotactically attracted to bile. However, there is still a paucity of information regarding which components and what concentration of bile induce the chemotactic behavior. Here, we show, among various bile components tested, two have opposing chemotactic influences on the CsNEJs; cholic acid was characterized as a chemoattractant and lithocholic acid as a chemorepellent. Chemorepulsive migration was dependent on the concentration of lithocholic acid. Notably, the ratio (25:1) of cholic acid and lithocholic acid plays a critical role in defining chemotactic preferences of CsNEJs. We suspect that this bile acid ratio directs the parasites in the mammalian host, i.e. the high concentration of lithocholic acid in the gallbladder bile may repel CsNEJs from entering it. Bile in the hepatic bile duct has a chemoattractive level of cholic acid but a trace amount of lithocholic acid. These findings may explain why the CsNEJs preferentially migrate to the common and hepatic bile ducts rather than the gallbladder. Deeper understanding on the parasitism of the liver fluke is likely to have major implications for the studies on other parasites.

Venom allergen-like protein 28 in Clonorchis sinensis: four epitopes on its surface and the potential role of Cys124 for its conformational stability

Venom allergen-like (VAL) proteins are important to host-parasite interactions. We previously demonstrated that a Clonorchis sinensis VAL (CsVAL) protein-derived synthetic peptide suppresses allergic and inflammatory responses. However, little is known regarding the physicochemical and antigenic properties of CsVAL proteins. Here, we identified a novel 194 amino acid VAL protein, named C. sinensis VAL 28 (CsVAL28), and characterized its functional motifs and structural details as a new member of the CAP superfamily. Unlike members of the Schistosoma mansoni VAL (SmVAL) family, CsVAL28 has a single CAP1 motif and six highly conserved disulfide bond-forming cysteines. Tertiary models of wild-type CsVAL28 and mutants were built using SmVAL4 as template via homology modeling. Normal mode analysis predicted that disulfide bond breaking by mutation of cysteine 124 to serine would greatly affect protein mobility. Four major immunoreactive linear epitopes were identified in the surface-exposed region or its vicinity via epitope mapping, using sera from clonorchiasis patients and healthy controls. Our findings provide in-depth knowledge on the structure-function properties of VAL proteins and may help determine highly antigenic regions for developing new diagnostic approaches.

Multidrug resistance-associated protein 4 is a bile transporter of Clonorchis sinensis simulated by in silico docking

BACKGROUND

Multidrug resistance-associated protein 4 (MRP4) is a member of the C subfamily of the ABC family of ATP-binding cassette (ABC) transporters. MRP4 regulates ATP-dependent efflux of various organic anionic substrates and bile acids out of cells. Since Clonorchis sinensis lives in host's bile duct, accumulation of bile juice can be toxic to the worm's tissues and cells. Therefore, C. sinensis needs bile transporters to reduce accumulation of bile acids within its body.

RESULTS

We cloned MRP4 (CsMRP4) from C. sinensis and obtained a cDNA encoding an open reading frame of 1469 amino acids. Phylogenetic analysis revealed that CsMRP4 belonged to the MRP/SUR/CFTR subfamily. A tertiary structure of CsMRP4 was generated by homology modeling based on multiple structures of MRP1 and P-glycoprotein. CsMRP4 had two membrane-spanning domains (MSD1 & 2) and two nucleotide-binding domains (NBD1 & 2) as common structural folds. Docking simulation with nine bile acids showed that CsMRP4 transports bile acids through the inner cavity. Moreover, it was found that CsMRP4 mRNA was more abundant in the metacercariae than in the adults. Mouse immune serum, generated against the CsMRP4-NBD1 (24.9 kDa) fragment, localized CsMRP4 mainly in mesenchymal tissues and oral and ventral suckers of the metacercariae and the adults.

CONCLUSIONS

Our findings shed new light on MRPs and their homologs and provide a platform for further structural and functional investigations on the bile transporters and parasites' survival.

Molecular and Structural Characterization of the Tegumental 20.6-kDa Protein in Clonorchis sinensis as a Potential Druggable Target

The tegument, representing the membrane-bound outer surface of platyhelminth parasites, plays an important role for the regulation of the host immune response and parasite survival. A comprehensive understanding of tegumental proteins can provide drug candidates for use against helminth-associated diseases, such as clonorchiasis caused by the liver fluke Clonorchis sinensis. However, little is known regarding the physicochemical properties of C. sinensis teguments. In this study, a novel 20.6-kDa tegumental protein of the C. sinensis adult worm (CsTegu20.6) was identified and characterized by molecular and in silico methods. The complete coding sequence of 525 bp was derived from cDNA clones and encodes a protein of 175 amino acids. Homology search using BLASTX showed CsTegu20.6 identity ranging from 29% to 39% with previously-known tegumental proteins in C. sinensis. Domain analysis indicated the presence of a calcium-binding EF-hand domain containing a basic helix-loop-helix structure and a dynein light chain domain exhibiting a ferredoxin fold. We used a modified method to obtain the accurate tertiary structure of the CsTegu20.6 protein because of the unavailability of appropriate templates. The CsTegu20.6 protein sequence was split into two domains based on the disordered region, and then, the structure of each domain was modeled using I-TASSER. A final full-length structure was obtained by combining two structures and refining the whole structure. A refined CsTegu20.6 structure was used to identify a potential CsTegu20.6 inhibitor based on protein structure-compound interaction analysis. The recombinant proteins were expressed in Escherichia coli and purified by nickel-nitrilotriacetic acid affinity chromatography. In C. sinensis, CsTegu20.6 mRNAs were abundant in adult and metacercariae, but not in the egg. Immunohistochemistry revealed that CsTegu20.6 localized to the surface of the tegument in the adult fluke. Collectively, our results contribute to a better understanding of the structural and functional characteristics of CsTegu20.6 and homologs of flukes. One compound is proposed as a putative inhibitor of CsTegu20.6 to facilitate further studies for anthelmintics.

Molecular and structural characteristics of multidrug resistance-associated protein 7 in Chinese liver fluke Clonorchis sinensis

Multidrug resistance-associated protein 7 (MRP7, ABCC10) is a C subfamily member of the ATP-binding cassette (ABC) superfamily. MRP7 is a lipophilic anion transporter that pumps endogenous and xenobiotic substrates from the cytoplasm to the extracellular milieu. Here, we cloned and characterized CsMRP7 as a novel ABC transporter from the Chinese liver fluke, Clonorchis sinensis. Full-length cDNA of CsMRP7 was 5174 nt, encoded 1636 amino acids (aa), and harbored a 147-bp 5'-untranslated region (5'-UTR) and 116-bp 3'-UTR. Phylogenetic analysis confirmed that CsMRP7 was closer to the ABCC subfamily than the ABCB subfamily. Tertiary structures of the N-terminal region (1-322 aa) and core region (323-1621 aa) of CsMRP7 were generated by homology modeling using glucagon receptor (PDB ID: 5ee7_A) and P-glycoprotein (PDB ID: 4f4c_A) as templates, respectively. CsMRP7 nucleotide-binding domain 2 (NBD2) was conserved more than NBD1, which was the sites of ATP binding and hydrolysis. Like typical long MRPs, CsMRP7 has an additional membrane-spanning domain 0 (MSD0) and cytoplasmic loop, along with a common structural fold consisting of MSD1-NBD1-MSD2-NBD2 as a single polypeptide assembly. MSD0, MSD1, and MSD2 consisted of TM1-7, TM8-13, and TM14-19, respectively. The CsMRP7 transcript was more abundant in the metacercariae than in the adult worms. Truncated NBD1 (39 kDa) and NBD2 (44 kDa) were produced in bacteria and mouse immune sera were raised. CsMRP7 was localized in the apical side of the intestinal epithelium, sperm in the testes and seminal receptacle, receptacle membrane, and mesenchymal tissue around intestine in the adult worm. These results provide molecular information and insights into structural and functional characteristics of CsMRP7 and homologs of flukes.

Genome-wide identification of antimicrobial peptides in the liver fluke, Clonorchis sinensis

The increase in prevalence of antimicrobial resistance makes the search for new antibiotic agents imperative. Antimicrobial peptides (AMPs) from natural resources have been recognized as suitable tools to combat antibiotic-resistant bacteria. The liver fluke Clonorchis sinensis living in germ-filled environments could be a good source of antimicrobials. Here, we report the use of a rational protocol that combines AMP predictions based on their physicochemical properties and their in vivo stability to discover AMP candidates from the entire genome of C. sinensis. To screen AMP candidates, in silico analyses based on the physicochemical properties of known AMPs, such as length, charge, isoelectric point, and in vitro and in vivo aggregation values were performed. To enhance their in vivo stability, proteins having proteolytic cleavage sites were excluded. As a consequence, four high-activity, highstability peptides were identified. These peptides could be potential starting materials for the development of new AMPs via structural modification and optimization. Thus, this study proposes a refined computational method to develop new AMPs and identifies four AMP candidates, which could serve as templates for further development of peptide antibiotics.

Transcriptome sequencing and analysis of the zoonotic parasite Spirometra erinacei spargana (plerocercoids)

BACKGROUND

Although spargana, which are the plerocercoids of Spirometra erinacei, are of biological and clinical importance, expressed sequence tags (ESTs) from this parasite have not been explored. To understand molecular and biological features of this parasite, sparganum ESTs were examined by large-scale EST sequencing and multiple bioinformatics tools.

METHODS

Total RNA was isolated from spargana and then ESTs were generated, assembled and sequenced. Many biological aspects of spargana were investigated using multi-step bioinformatics tools.

RESULTS

A total of 5,634 ESTs were collected from spargana. After clustering and assembly, the functions of 1,794 Sparganum Assembled ESTs (SpAEs) including 934 contigs and 860 singletons were analyzed. A total of 1,351 (75%) SpAEs were annotated using a hybrid of BLASTX and InterProScan. Of these genes, 1,041 (58%) SpAEs had high similarity to tapeworms. In the context of the biology of sparganum, our analyses reveal: (i) a highly expressed fibronectin 1, a ubiquitous and abundant glycoprotein; (ii) up-regulation of enzymes related with glycolysis pathway; (iii) most frequent domains of protein kinase and RNA recognition motif domain; (iv) a set of helminth-parasitic and spargana-specific genes that may offer a number of antigen candidates.

CONCLUSIONS

Our transcriptomic analysis of S. erinacei spargana demonstrates biological aspects of a parasite that invades and travels through subcutaneous tissue in intermediate hosts. Future studies should include comparative analyses using combinations of transcriptome and proteome data collected from the entire life cycle of S. erinacei.

ClonorESTdb: a comprehensive database for Clonorchis sinensis EST sequences

Background

Clonorchiasis, which is primarily caused by liver fluke (Platyhelminthes), is a fatal infectious disease that is mainly associated with bile duct malignancy and the subsequent development of cholangiocarcinoma. Thus, a genomic approach now represents an important step to further our knowledge of biology and the pathology of these parasites. The results of expressed sequence tags (ESTs) sequencing need to be well organized into databases to provide an integrated set of tools and functional information.

Findings

Here, the ClonorESTdb database represents a collection of Clonorchis sinensis ESTs that is intended as a resource for parasite functional genomics. A total of 55,736 successful EST sequences, which are cleaned and clustered into non-redundant 13,305 C. sinensis assembled EST sequences (6,497 clusters and 6,808 singletons), were obtained from three in-house prepared cDNA libraries of C. sinensis at different developmental stages. The assembled consensus sequences were annotated using the BLAST algorithm or/and hmm against NCBI NR, UniProt, KEGG and InterProScan. The ClonorESTdb database provides functional annotation, their expression profiles, tandem repeats and putative single nucleotide polymorphisms with utility tools such as local BLAST search and text retrieval.

Conclusions

This resource enables the researcher to identify and compare expression signatures under different biological stages and promotes ongoing parasite drug and vaccine development and biological research.

Database URL:http://pathod.cdc.go.kr/clonorestdb/

Identification of CDH23 mutations in Korean families with hearing loss by whole-exome sequencing

Background

Patient genetic heterogeneity renders it difficult to discover disease-cause genes. Whole-exome sequencing is a powerful new strategy that can be used to this end. The purpose of the present study was to identify a hitherto unknown mutation causing autosomal recessive nonsyndromic hearing loss (ARNSHL) in Korean families.

Methods

We performed whole-exome sequencing in 16 individuals from 13 unrelated small families with ARNSHL. After filtering out population-specific polymorphisms, we focused on known deafness genes. Pathogenic effects of the detected mutations on protein structure or function were predicted via in silico analysis.

Results

We identified compound heterozygous CDH23 mutations in hearing-loss genes of two families. These include two previously reported pathological mutations, p.Pro240Leu and p.Glu1595Lys, as well as one novel mutation, p.Asn342Ser. The p.Pro240Leu mutation was found in both families. We also identified 26 non-synonymous variants in CDH23 coding exons from 16 hearing-loss patients and 30 Korean exomes.

Conclusion

The present study is the first to show that CDH23 mutations cause hearing loss in Koreans. Although the precise contribution made by such mutations needs to be determined using a larger patient cohort, our data indicate that mutations in the CDH23 gene are one of the most important causes of non-syndromic hearing loss in East Asians. Further exome sequencing will identify common mutations or polymorphisms and contribute to the molecular diagnosis of, and development of new therapies for, hereditary hearing loss.

Semantic Modeling for SNPs Associated with Ethnic Disparities in HapMap Samples

Single-nucleotide polymorphisms (SNPs) have been emerging out of the efforts to research human diseases and ethnic disparities. A semantic network is needed for in-depth understanding of the impacts of SNPs, because phenotypes are modulated by complex networks, including biochemical and physiological pathways. We identified ethnicity-specific SNPs by eliminating overlapped SNPs from HapMap samples, and the ethnicity-specific SNPs were mapped to the UCSC RefGene lists. Ethnicity-specific genes were identified as follows: 22 genes in the USA (CEU) individuals, 25 genes in the Japanese (JPT) individuals, and 332 genes in the African (YRI) individuals. To analyze the biologically functional implications for ethnicity-specific SNPs, we focused on constructing a semantic network model. Entities for the network represented by "Gene," "Pathway," "Disease," "Chemical," "Drug," "ClinicalTrials," "SNP," and relationships between entity-entity were obtained through curation. Our semantic modeling for ethnicity-specific SNPs showed interesting results in the three categories, including three diseases ("AIDS-associated nephropathy," "Hypertension," and "Pelvic infection"), one drug ("Methylphenidate"), and five pathways ("Hemostasis," "Systemic lupus erythematosus," "Prostate cancer," "Hepatitis C virus," and "Rheumatoid arthritis"). We found ethnicity-specific genes using the semantic modeling, and the majority of our findings was consistent with the previous studies - that an understanding of genetic variability explained ethnicity-specific disparities.

DNA barcoding of fish, insects, and shellfish in Korea

DNA barcoding has been widely used in species identification and biodiversity research. A short fragment of the mitochondrial cytochrome c oxidase subunit I (COI) sequence serves as a DNA bio-barcode. We collected DNA barcodes, based on COI sequences from 156 species (529 sequences) of fish, insects, and shellfish. We present results on phylogenetic relationships to assess biodiversity the in the Korean peninsula. Average GC% contents of the 68 fish species (46.9%), the 59 shellfish species (38.0%), and the 29 insect species (33.2%) are reported. Using the Kimura 2 parameter in all possible pairwise comparisons, the average interspecific distances were compared with the average intraspecific distances in fish (3.22 vs. 0.41), insects (2.06 vs. 0.25), and shellfish (3.58 vs. 0.14). Our results confirm that distance-based DNA barcoding provides sufficient information to identify and delineate fish, insect, and shellfish species by means of all possible pairwise comparisons. These results also confirm that the development of an effective molecular barcode identification system is possible. All DNA barcode sequences collected from our study will be useful for the interpretation of species-level identification and community-level patterns in fish, insects, and shellfish in Korea, although at the species level, the rate of correct identification in a diversified environment might be low.

SpiroESTdb: a transcriptome database and online tool for sparganum expressed sequences tags

Background

Sparganum (plerocercoid of Spirometra erinacei) is a parasite that possesses the remarkable ability to survive by successfully modifying its physiology and morphology to suit various hosts and can be found in various tissues, even the nervous system. However, surprisingly little is known about the molecular function of genes that are expressed during the course of the parasite life cycle. To begin to decipher the molecular processes underlying gene function, we constructed a database of expressed sequence tags (ESTs) generated from sparganum.

Findings

SpiroESTdb is a web-based information resource that is built upon the annotation and curation of 5,655 ESTs data. SpiroESTdb provides an integrated platform for expressed sequence data, expression dynamics, functional genes, genetic markers including single nucleotide polymorphisms and tandem repeats, gene ontology and KEGG pathway information. Moreover, SpiroESTdb supports easy access to gene pages, such as (i) curation and query forms, (ii) in silico expression profiling and (iii) BLAST search tools. Comprehensive descriptions of the sparganum content of all sequenced data are available, including summary reports. The contents of SpiroESTdb can be viewed and downloaded from the web (http://pathod.cdc.go.kr/spiroestdb).

Conclusions

This integrative web-based database of sequence data, functional annotations and expression profiling data will serve as a useful tool to help understand and expand the characterization of parasitic infections. It can also be used to identify potential industrial drug targets and vaccine candidate genes.

Tracing of the Bile-chemotactic migration of juvenile Clonorchis sinensis in rabbits by PET-CT

Background

Adult Clonorchis sinensis live in the bile duct and cause clonorchiasis. It is known that the C. sinensis metacercariae excyst in the duodenum and migrate up to the bile duct through the common bile duct. However, no direct evidence is available on the in vivo migration of newly excysted C. sinensis juveniles (CsNEJs). Advanced imaging technologies now allow the in vivo migration and localization to be visualized. In the present study, we sought to determine how sensitively CsNEJs respond to bile and how fast they migrate to the intrahepatic bile duct using PET-CT.

Methodology/Principal Findings

CsNEJs were radiolabeled with ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG). Rabbits with a gallbladder contraction response to cholecystokinin-8 (CCK-8) injection were pre-screened using cholescintigraphy. In these rabbits, gallbladders contracted by 50% in volume at an average of 11.5 min post-injection. The four rabbits examined were kept anesthetized and a catheter inserted into the mid duodenum. Gallbladder contraction was stimulated by injecting CCK-8 (20 ng/kg every minute) over the experiment. Anatomical images were acquired by CT initially and dynamic PET was then carried out for 90 min with a 3-min acquisition per frame. Twelve minutes after CCK-8 injection, about 3,000 ¹⁸F-FDG-labeled CsNEJs were inoculated into the mid duodenum through the catheter. Photon signals were detected in the liver 7–9 min after CsNEJs inoculation, and these then increased in the whole liver with stronger intensity in the central area, presenting that the CsNEJs were arriving at the intrahepatic bile ducts.

Conclusion

In the duodenum, CsNEJs immediately sense bile and migrate quickly with bile-chemotaxis to reach the intrahepatic bile ducts by way of the ampulla of Vater.

Clonorchis sinensis adults habituating in the bile duct cause clonorchiasis endemic in East Asian countries, in which about 15–20 million people are supposedly infected. It has previously been reported that C. sinensis metacercariae excyst in the duodenum and that the juvenile flukes migrate to the bile duct through the ampulla of Vater in 4–7 hours. Recently advanced imaging technologies have enabled visualization of movements and localizations of parasites in mammalian hosts. From present study, we found the following: newly excysted C. sinensis juveniles (CsNEJs) were efficiently in vitro radiolabeled with ¹⁸F-FDG since CsNEJs have glucose transporters; CCK-8-induced gallbladder contraction was various rabbit to rabbit; CsNEJs promptly recognized bile and migrated up the duodenum to reach the intrahepatic bile ducts by way of the ampulla of Vater and the common bile duct as early as 7–9 minutes after inoculation. Some CsNEJs responding slowly to the bile delayed arriving at the distal bile capillaries. It was visualized for the first time that the CsNEJs migrate quickly within 10–20 minutes from the duodenum to the intrahepatic bile duct. These findings provide fundamental information on the migration of parasites living in the biliary passages of mammals.

The identification of antigenic proteins: 14-3-3 protein and propionyl-CoA carboxylase in Clonorchis sinensis

Clonorchis sinensis, the causative agent of clonorchiasis, is widespread in East and Southeast Asia, including China, Vietnam and the Republic of Korea. We identified antigenic proteins from adult C. sinensis liver flukes using immunoproteomic analysis. In this study, we found 23 candidate antigenic proteins with a pI in the range of 5.4-6.2 in total lysates of C. sinensis. The antigenic protein spots reacted against sera from clonorchiasis patients and were identified as cysteine proteases, glutathione transferases, gelsolin, propionyl-CoA carboxylase (PCC), prohibitin and 14-3-3 protein (14-3-3) using LC-coupled ESI-MS/MS and an EST database for C. sinensis. PCC and 14-3-3 were identified for the first time as serological antigens for the diagnosis of C. sinensis. To validate the antigenicity of PCC and 14-3-3, recombinant proteins were immunoblotted with sera from clonorchiasis patients. The structural, functional and immunological characteristics of the putative amino acid sequence were predicted by bioinformatics analysis. Our novel finding will contribute to the development of diagnostics for clonorchiasis. These results suggest that immunoproteomic approaches are valuable tools to identify antigens that could be used as targets for effective parasitic infection control strategies.

Developmental transcriptomic features of the carcinogenic liver fluke, Clonorchis sinensis

Clonorchis sinensis is the causative agent of the life-threatening disease endemic to China, Korea, and Vietnam. It is estimated that about 15 million people are infected with this fluke. C. sinensis provokes inflammation, epithelial hyperplasia, and periductal fibrosis in bile ducts, and may cause cholangiocarcinoma in chronically infected individuals. Accumulation of a large amount of biological information about the adult stage of this liver fluke in recent years has advanced our understanding of the pathological interplay between this parasite and its hosts. However, no developmental gene expression profiles of C. sinensis have been published. In this study, we generated gene expression profiles of three developmental stages of C. sinensis by analyzing expressed sequence tags (ESTs). Complementary DNA libraries were constructed from the adult, metacercaria, and egg developmental stages of C. sinensis. A total of 52,745 ESTs were generated and assembled into 12,830 C. sinensis assembled EST sequences, and then these assemblies were further categorized into groups according to biological functions and developmental stages. Most of the genes that were differentially expressed in the different stages were consistent with the biological and physical features of the particular developmental stage; high energy metabolism, motility and reproduction genes were differentially expressed in adults, minimal metabolism and final host adaptation genes were differentially expressed in metacercariae, and embryonic genes were differentially expressed in eggs. The higher expression of glucose transporters, proteases, and antioxidant enzymes in the adults accounts for active uptake of nutrients and defense against host immune attacks. The types of ion channels present in C. sinensis are consistent with its parasitic nature and phylogenetic placement in the tree of life. We anticipate that the transcriptomic information on essential regulators of development, bile chemotaxis, and physico-metabolic pathways in C. sinensis that presented in this study will guide further studies to identify novel drug targets and diagnostic antigens.

Reference genes for quantitative analysis on Clonorchis sinensis gene expression by real-time PCR

The accuracies of relative gene expressions as determined by quantitative real-time polymerase chain reaction are largely dependent on the variabilities of the reference genes used. Validation of the stabilities of reference genes under experimental conditions is an essential initial step for comparative studies on the expression levels of target genes in experimental groups. Using three total RNA samples extracted independently from Clonorchis sinensis metacercariae and adults, we determined the gene expression stabilities of eight reference gene candidates and the relative transcript levels of three target genes using the geNorm program. The reference genes found to be stably expressed in metacercariae and adults were phosphoglycerate kinase, beta-actin, and calcyphosine; reference genes found to be stably expressed under gamma-irradiated and non-irradiated conditions were succinate dehydrogenase, small nuclear ribonucleoprotein, and beta-actin; and those stably expressed regardless of bile treatment were small nuclear ribonucleoprotein, phosphoglycerate kinase, and succinate dehydrogenase. According to our data, the expression levels of target genes are dependent on normalization factors, such as the C (T) values of single reference genes and the geometric mean of the C (T) values of three reference genes. When comparing C. sinensis gene expressions, we propose to employ the geometric mean of the C (T) values of more than three reference genes validated in the same experimental setting.

Changes in neck muscle electromyography and forward head posture of children when carrying schoolbags

This study tested the effects of three alternative types of backpack on head posture and neck muscle electromyography (EMG) in children. Four loading conditions were tested: no pack; a backpack; a double pack; a modified double pack (designed with a backpack and a front pack weighing 10% and 5% of body weight, respectively). Dependent variables were neck muscle activity, forward head angle and forward head distance (the perpendicular distance from C7 to a vertical line through the tragus of the ear). Fifteen children were asked to walk at a speed of 0.8 m/s on a treadmill. The EMG activity of upper trapezius, sternocleidomastoid and midcervical paraspinals muscles and the forward head angle and forward head distance were all significantly higher when carrying a backpack than for the other conditions. When carrying a double pack, there was a backward head posture characterised by an increased negative forward head angle, decreased forward head distance, increased sternocleidomastoid EMG signal and decreased midcervical paraspinals EMG signal, compared to carrying no pack. When carrying a modified double pack, the forward head angle and forward head distance decreased when compared to carrying a backpack. These findings indicate that the modified double pack minimises postural deviation.

Molecular cloning and characterization of WD40-repeat protein from Clonorchis sinensis

WD40-repeat proteins have four to eight repeating units flanked by Gly-His (GH) and Trp-Asp (WD) at both termini and folds into a beta-propeller. A polypeptide deduced from a Clonorchis sinensis cDNA clone analyzed to have seven WD40-repeats and predicted to form a beta-propeller (CsWD1). The CsWD1 protein was expressed stage-specifically in the metacercariae and localized in the tegumental syncytium. The CsWD1 protein is suggested to serve as a platform for interacting partner proteins in the tegumental syncytium of C. sinensis metacercariae.