Echinococcosis Is Associated with the Increased Prevalence of Intestinal Blastocystis Infection in Tibetans and Host Susceptibility to the Blastocystis in Mice.

Blastocystis is a common human intestinal protozoan parasite. Little is known about its prevalence in echinococcosis. This study tested whether Echinococcus multilocularis infection would increase host susceptibility to Blastocystis. A total of 114 fecal samples (68 hydatid disease patients and 46 healthy people) were collected from Tibetans in the Qinghai province in China. The presence of Blastocystis was identified by sequencing of the small subunit (SSU) rRNA gene. Balb/c mice were co-infected with Blastocystis and E. multilocularis and tested for host susceptibility to Blastocystis. The overall Blastocystis prevalence was 12.3%; 16.2% in the patients and 4.4% in healthy people (p < 0.05). Sequence analysis identified three known Blastocystis genotypes, including ST1, ST2, and ST3, and one unknown genotype. Experimental dual infection significantly reduced mouse survival rate (20%), induced more severe signs, and increased intestinal damages with a higher intestinal colonization level of Blastocystis. The mouse model showed that E. multilocularis infection increases host susceptibility to Blastocystis. Our study shows a significantly higher prevalence of Blastocystis in patients with liver echinococcosis and reveals that non-intestinal E. multilocularis infection increases host susceptibility to the Blastocystis. Our results highlight that E. multilocularis infection is associated with Blastocystis. These findings remind us that more attention should be paid to the gut health of the patients with a helminth infection during clinical patient care.

Newly excysted juveniles of Fasciola gigantica trigger the release of water buffalo neutrophil extracellular traps in vitro.

Polymorphonuclear neutrophils (PMNs) are the most abundant leukocytes and are among the first line of immune system defense. PMNs can form neutrophil extracellular traps (NETs) in response to some pathogens. The release of NETs plays an important role in trapping and killing invading parasites. However, the effects of NETs on parasitic trematode infections remain unclear. In the present study, water buffalo NET formation, triggered by the newly excysted juveniles (NEJs) of Fasciola gigantica, was visualized by scanning electron microscopy. The major components of the structure of NETs were characterized by immunofluorescence. Viability of flukes incubated with water buffalo PMNs were examined under light microscopy. The results revealed that F. gigantic juveniles triggered PMN-mediated NETs. These NETs were confirmed to comprise the classic characteristics of NETs: DNA, histones, myeloperoxidase and neutrophil elastase. Although NETs were formed in response to viable larvae, the larvae were not killed in vitro. These results suggest that NET formation may serve as a mechanism to hamper the migration of large larvae to facilitate immune cells to kill them. This study demonstrates, for the first time, that parasitic trematode juveniles can trigger NET formation.

Expression profiles of genes involved in TLRs and NLRs signaling pathways of water buffaloes infected with Fasciola gigantica.

Infection of ruminants and humans with Fasciola gigantica is attracting increasing attention due to its economic impact and public health significance. However, little is known of innate immune responses during F. gigantica infection. Here, we investigated the expression profiles of genes involved in Toll-like receptors (TLRs) and NOD-like receptors (NLRs) signaling pathways in buffaloes infected with 500F. gigantica metacercariae. Serum, liver and peripheral blood mononuclear cell (PBMC) samples were collected from infected and control buffaloes at 3, 10, 28, and 70days post infection (dpi). Then, the levels of 12 cytokines in serum samples were evaluated by ELISA. Also, the levels of expression of 42 genes, related to TLRs and NLRs signaling, in liver and PBMCs were determined using custom RT2 Profiler PCR Arrays. At 3 dpi, modest activation of TLR4 and TLR8 and the adaptor protein (TICAM1) was detected. At 10 dpi, NF-κB1 and Interferon Regulatory Factor signaling pathways were upregulated along with activation of TLR1, TLR2, TLR6, TLR10, TRAF6, IRF3, TBK1, CASP1, CD80, and IFNA1 in the liver, and inflammatory response with activated TLR4, TLR9, TICAM1, NF-κB1, NLRP3, CD86, IL-1B, IL-6, and IL-8 in PBMCs. At 28 dpi, there was increase in the levels of cytokines along with induction of NLRP1 and NLRP3 inflammasomes-dependent immune responses in the liver and PBMCs. At 70 dpi, F. gigantica activated TLRs and NLRs, and their downstream interacting molecules. The activation of TLR7/9 signaling (perhaps due to increased B-cell maturation and activation) and upregulation of NLRP3 gene were also detected. These findings indicate that F. gigantica alters the expression of TLRs and NLRs genes to evade host immune defenses. Elucidation of the roles of the downstream effectors interacting with these genes may aid in the development of new interventions to control disease caused by F. gigantica infection.

Serum levels of cytokines in water buffaloes experimentally infected with Fasciola gigantica.

Fasciola gigantica infection in water buffaloes causes significant economic losses especially in developing countries. Although modulation of the host immune response by cytokine neutralization or vaccination is a promising approach to control infection with this parasite, our understanding of cytokine's dynamic during F. gigantica infection is limited. To address this, we quantified the levels of serum cytokines produced in water buffaloes following experimental infection with F. gigantica. Five buffaloes were infected via oral gavage with 500 viable F. gigantica metacercariae and blood samples were collected from buffaloes one week before infection and for 13 consecutive weeks thereafter. The levels of 10 cytokines in serum samples were simultaneously determined using ELISA. F. gigantica failed to elicit the production of various pro-inflammatory cytokines, including interleukin-1ß (IL-1ß), IL-2, IL-6, IL-12, and IFN-γ. On the other hand, evidence of a Th2 type response was detected, but only early in the course of parasite colonization and included modest increase in the levels of IL-10 and IL-13. The results also revealed suppression of the immune responses as a feature of chronic F. gigantica infection in buffaloes. Taken together, F. gigantica seems to elicit a modest Th2 response at early stage of infection in order to downregulate harmful Th1- and Th17-type inflammatory responses in experimentally infected buffaloes. The full extent of anti-F. gigantica immune response and its relation to pathogenesis requires further study.

Transcriptomic responses of water buffalo liver to infection with the digenetic fluke Fasciola gigantica.

BACKGROUND: Fasciola gigantica, the tropical liver fluke, infects buffaloes in Asian and African countries and causes significant economic losses and poses public health threat in these countries. However, little is known of the transcriptional response of buffaloes to infection with F. gigantica. The objective of the present study was to perform the first transcriptomic analysis of buffalo liver infected by F. gigantica. Understanding the mechanisms that underpin F. gigantica infection in buffaloes will contribute to our ability to control this parasite. METHODS: We challenged buffaloes with 500 viable F. gigantica metacercariae and collected liver samples through a time course at 3, 42 and 70 days post-infection (dpi). Then, we performed gene expression analysis on liver samples using RNA sequencing (RNA-Seq) Illumina technology and confirmed the RNA-Seq data by quantitative RT-PCR analysis. RESULTS: Totals of 496, 880 and 441 differentially expressed transcripts were identified in the infected livers at 3, 42 and 70 dpi, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that transcriptional changes in the liver of infected buffaloes evolve over the course of infection. The predominant response of buffaloes to infection was mediated by certain pathways, such as MHC antigen processing and presentation, Toll-like receptor 4 (TLR4), transforming growth factor beta (TGF-ß), and the cytochrome P450. Hepatic drug metabolizing enzymes and bile secretion were also affected. CONCLUSIONS: Fasciola gigantica can induce statistically significant and biologically plausible differences in the hepatic gene expression of infected buffaloes. These findings provide new insights into the response of buffaloes to F. gigantica over the course of infection, which may be useful in determining pathways that can modulate host-parasite interaction and thus potentially important for clearance of the parasite.

[Identification of Taenia solium Insulin Receptor TsIR-1316 and Expression of Its Ligand Binding Domain].

Objective: To characterize the structure of insulin receptor of Taenia solium（TsIR-1316） and express its ligand binding domain (LBD). Methods: Primers for TsIR-1316 were designed according to the genomic data of T. solium, and the TsIR-1316 gene was amplified by PCR. The nucleotide and amino acid sequences of TsIR-1316 were aligned using BLASTN and BLASTP, and the putative signal peptide and structure domains were predicted. The LBD fragment of TsIR-1316 was cloned into the pET-30a（+） vector and expressed. The expressed proteins were purified, separated by SDS-PAGE and analyzed with Western blotting using cysticercus cellulosae-positive serum and TsIR-LBD-immunized rabbit serum. Results: The open reading frame of TsIR-1316 was 5 196 bp, encoded a protein of 1 732 amino acids which had a typical conserved domain of tyrosine kinase family, was 84% homologous with Echinococcus multilocularis, and had a "V"-shaped tertiary structure. As expected, SDS-PAGE showed that the expressed protein had a band at Mr 59 000. Western blotting showed that the recombinant protein had specific reactions with cysticercus cellulosae positive serum and TsIR-LBD immunized rabbit serum, resulting in a specific band at M(r) 59 000. Conclusion: The TsIR-1316 gene was successfully cloned and identified. The expressed protein of TsIR-1316 LBD can be recognized by cysticercus cellulosae positive serum, which suggests a good antigenicity of this protein.

[Identification, Expression and Antigenicity Analysis of Serpin B6 of Taenia solium].

Objective: To identify and express serpin B6 of Taenia solium (Tsserpin B6) and explore its possible use as a diagnostic antigen. Methods: Primers for Tsserpin B6 were designed according to T. solium genome and transcriptome data. The Tsserpin B6 gene was amplified from the total RNA of T. solium cysticercus and subsequently analyzed by bioinformatics. Multiple amino acid sequence alignments of Tsserpin B6 and other parasites serpins were created using the Clustal X1.83. Phylogenetic analyses were performed using the MEGA 6.0. The recombinant expression vector pET-30a-Tsserpin B6 was constructed and expressed in E. coli strain BL21 （DE3）. The expressed proteins were purified, isolated by SDS-PAGE, and analyzed by Western blotting using pig serum infected with T. solium cysticerci. Results: The complete reading frame of Tsserpin B6 was 1 131 bp and encoded a protein of 376 amino acids. The encoded protein had a conservative reactive center loop and distinctive domains of NEEGAE and FTVDHPFLF, and harbored 9 potential linear B cell epitopes. The expressed products of Tsserpin B6 mainly existed as an inclusion body, and reacted with pig serum infected with T. solium, resulting in a specific band at the Mr 53 000. Conclusion: The Tsserpin B6 gene was successfully cloned, and its expressed products can be recognized by pig serum infected with T. solium.

Molecular identification of Diphyllobothrium latum and a brief review of diphyllobothriosis in China.

Two tapeworm specimens collected in northeast China in 2009 and 2011 were identified as Diphyllobothrium latum based on morphological criteria. Molecular methods were used to confirm their identity and analyze genetic variations compared with published data for this species. Species identity was confirmed by molecular characterization of the 18S rDNA partial sequence, complete sequences of internal transcribed spacers (ITSs) and 5.8S rDNA, and partial sequences of mitochondrial cytochrome c oxidase subunit 1 (cox1) and mitochondrial NADH dehydrogenase subunit 5 (nad5). PCR amplification and sequence analysis of 18S rDNA (1472 bp), ITS regions (1218 bp), cox1 (885 bp), and nad5 (1028 bp) revealed that these four sequences showed more than 99% identity to reference sequences for D. latum, confirming that this species is D. latum. To date, a total of 12 diphyllobothriosis cases have been documented in China. This study represents the first molecular characterization of D. latum in China, providing molecular evidence of human diphyllobothriosis in China.

Genetic variation of the 8-kDa glycoprotein family from Echinococcus granulosus, Taenia multiceps and Taenia hydatigena.

BACKGROUND: Echinococcosis, coenurosis and cysticercosis are debilitating diseases which prevail in China. Immunological diagnosis of metacestodosis is important in disease control. The 8-kDa glycoproteins from taeniid cestodes have successfully been used for diagnosis of human cysticercosis in immunological assays. The aim of the present study was to investigate genetic variations and phylogenetic relationships of the 8-kDa proteins for evaluating the possibility of utilizing these proteins as diagnostic antigens for other metacestode infections. METHODS: The genes and complementary DNAs (cDNAs) encoding the 8-kDa proteins from Echinococcus (E.) granulosus, Taenia (T.) multiceps and T. hydatigena were amplified using PCR method. Their amplicons were cloned into the vector pMD18 and the positive clones were sequenced. Sequence data were analyzed with the SeqMan program, and sequence homology searches were performed using the BLAST program. Alignments were conducted using the ClustalX program, and the phylogenetic analyses were performed with the Protein Sequences Program and the Puzzle Program using the Neighbor-joining method. RESULTS: Fifteen, 18 and 22 different genomic DNA sequences were identified as members of the 8-kDa protein gene family from E. granulosus, T. multiceps and T. hydatigena, respectively. Eight, four and six different cDNA clones respectively from E. granulosus, T. multiceps and T. hydatigena were characterized. Analysis of these sequences revealed 54 unique 8-kDa protein sequences. Phylogenetic trees demonstrated that the taeniid 8-kDa proteins are clustered into eight clades at least: Ts18, Ts14, TsRS1, TsRS2, T8kDa-1, T8kDa-2, T8kDa-3 and T8kDa-4. CONCLUSION: We found that the gene family encoding for the taeniid 8-kDa antigens is comprised of many members with high diversity, which will provide molecular evidence for cross-reaction or specific reaction among metacestode infections and may contribute to the development of promising immunological methods for diagnosis of metacestodosis.

Complete mitochondrial genomes of Taenia multiceps, T. hydatigena and T. pisiformis: additional molecular markers for a tapeworm genus of human and animal health significance.

BACKGROUND: Mitochondrial genomes provide a rich source of molecular variation of proven and widespread utility in molecular ecology, population genetics and evolutionary biology. The tapeworm genus Taenia includes a diversity of tapeworm parasites of significant human and veterinary importance. Here we add complete sequences of the mt genomes of T. multiceps, T. hydatigena and T. pisiformis, to a data set of 4 published mtDNAs in the same genus. Seven complete mt genomes of Taenia species are used to compare and contrast variation within and between genomes in the genus, to estimate a phylogeny for the genus, and to develop novel molecular markers as part of an extended mitochondrial toolkit. RESULTS: The complete circular mtDNAs of T. multiceps, T. hydatigena and T. pisiformis were 13,693, 13,492 and 13,387 bp in size respectively, comprising the usual complement of flatworm genes. Start and stop codons of protein coding genes included those found commonly amongst other platyhelminth mt genomes, but the much rarer initiation codon GTT was inferred for the gene atp6 in T. pisiformis. Phylogenetic analysis of mtDNAs offered novel estimates of the interrelationships of Taenia. Sliding window analyses showed nad6, nad5, atp6, nad3 and nad2 are amongst the most variable of genes per unit length, with the highest peaks in nucleotide diversity found in nad5. New primer pairs capable of amplifying fragments of variable DNA in nad1, rrnS and nad5 genes were designed in silico and tested as possible alternatives to existing mitochondrial markers for Taenia. CONCLUSIONS: With the availability of complete mtDNAs of 7 Taenia species, we have shown that analysis of amino acids provides a robust estimate of phylogeny for the genus that differs markedly from morphological estimates or those using partial genes; with implications for understanding the evolutionary radiation of important Taenia. Full alignment of the nucleotides of Taenia mtDNAs and sliding window analysis suggests numerous alternative gene regions are likely to capture greater nucleotide variation than those currently pursued as molecular markers. New PCR primers developed from a comparative mitogenomic analysis of Taenia species, extend the use of mitochondrial markers for molecular ecology, population genetics and diagnostics.

[Application of filamentous phage display technology in parasitology].

This review focuses on the application of phage display technology in the prevention, diagnosis and treatment of parasitic diseases. It covers: (1) an introduction of phage display technology, filamentous phage and the advantage of carrier. (2) Construction of phage antibody libraries of parasites, epitope mapping and mimotope, and their potential application in the development of novel diagnostic reagents and vaccines.