Calreticulin (CALR), a multifunctional protein thoroughly researched in mammals, comprises N-, P-, and C-domain and has roles in calcium homeostasis, chaperoning, clearance of apoptotic cells, cell adhesion, and also angiogenesis. In this study, the spatial and temporal expression patterns of the Opisthorchis viverrini CALR gene were analyzed, and calcium-binding and chaperoning properties of recombinant O. viverrini CALR (OvCALR) investigated. OvCALR mRNA was detected from the newly excysted juvenile to the mature parasite by RT-PCR while specific antibodies showed a wide distribution of the protein. OvCALR was localized in tegumental cell bodies, testes, ovary, eggs, Mehlis’ gland, prostate gland, and vitelline cells of the mature parasite. Recombinant OvCALR showed an in vitro suppressive effect on the thermal aggregation of citrate synthase. The recombinant OvCALR C-domain showed a mobility shift in native gel electrophoresis in the presence of calcium. The results imply that OvCALR has comparable function to the mammalian homolog as a calcium-binding molecular chaperone. Inferred from the observed strong immunostaining of the reproductive tissues, OvCALR should be important for reproduction and might be an interesting target to disrupt parasite fecundity. Transacetylase activity of OvCALR as reported for calreticulin of Haemonchus contortus could not be observed.
Antibodies ; Calcium ; Calreticulin* ; Cell Adhesion ; Cell Body ; Citrate (si)-Synthase ; Eggs ; Electrophoresis ; Female ; Fertility ; Haemonchus ; Homeostasis ; In Vitro Techniques ; Mammals ; Molecular Chaperones ; Opisthorchis* ; Ovary ; Ovum ; Parasites ; Prostate ; Reproduction ; RNA, Messenger ; Testis ; Vitellins

The DM9 domain is a protein unit of 60-75 amino acids that has been first detected in the fruit fly Drosophila as a repeated motif of unknown function. Recent research on proteins carrying DM9 domains in the mosquito Anopheles gambiae and the oyster Crassostrea gigas indicated an association with the uptake of microbial organisms. Likewise, in the trematode Fasciola gigantica DM9-1 showed intracellular relocalization following microbial, heat and drug stress. In the present research, we show that FgDM9-1 is a lectin with a novel mannose-binding site that has been recently described for the protein CGL1 of Crassostrea gigas. This property allowed FgDM9-1 to agglutinate gram-positive and -negative bacteria with appropriate cell surface glycosylation patterns. Furthermore, FgDM9-1 caused hemagglutination across all ABO blood group phenotypes. It is speculated that the parenchymal located FgDM9-1 has a role in cellular processes that involve the transport of mannose-carrying molecules in the parenchymal cells of the parasite.

A rumen fluke Fischoederius elongatus is assigned to the type species of genus Fischoederius, family Gastrothylacidae. However, the mitochondrial sequences recently published are thought to be of inconsistent species, suggesting that several morphologically similar but genetically distinct species might be classified as Fischoederius elongatus. Thus, mentions of F. elongatus from South, Southeast, and East Asia might unintentionally refer to different species. The present work describes morphology and a full mitochondrial genome sequence of one of these species. The fluke specimens were collected from 2 infected cattle in Thailand. An interesting finding was the presence of a second tRNA-Asp gene next to a partial ND1 gene. It is suggested that these duplicated sequences are the remnants of non-reciprocal recombination events caused by inverted repeats located between ND2 and ND1 mitochondrial genes.

The DM9 domain is a protein unit of 60-75 amino acids that has been first detected in the fruit fly Drosophila as a repeated motif of unknown function. Recent research on proteins carrying DM9 domains in the mosquito Anopheles gambiae and the oyster Crassostrea gigas indicated an association with the uptake of microbial organisms. Likewise, in the trematode Fasciola gigantica DM9-1 showed intracellular relocalization following microbial, heat and drug stress. In the present research, we show that FgDM9-1 is a lectin with a novel mannose-binding site that has been recently described for the protein CGL1 of Crassostrea gigas. This property allowed FgDM9-1 to agglutinate gram-positive and -negative bacteria with appropriate cell surface glycosylation patterns. Furthermore, FgDM9-1 caused hemagglutination across all ABO blood group phenotypes. It is speculated that the parenchymal located FgDM9-1 has a role in cellular processes that involve the transport of mannose-carrying molecules in the parenchymal cells of the parasite.

A rumen fluke Fischoederius elongatus is assigned to the type species of genus Fischoederius, family Gastrothylacidae. However, the mitochondrial sequences recently published are thought to be of inconsistent species, suggesting that several morphologically similar but genetically distinct species might be classified as Fischoederius elongatus. Thus, mentions of F. elongatus from South, Southeast, and East Asia might unintentionally refer to different species. The present work describes morphology and a full mitochondrial genome sequence of one of these species. The fluke specimens were collected from 2 infected cattle in Thailand. An interesting finding was the presence of a second tRNA-Asp gene next to a partial ND1 gene. It is suggested that these duplicated sequences are the remnants of non-reciprocal recombination events caused by inverted repeats located between ND2 and ND1 mitochondrial genes.

Four isoforms of calcium binding proteins containing 2 EF hand motifs and a dynein light chain-like domain in the human liver fluke Opisthorchis viverrini, namely OvCaBP1, 2, 3, and 4, were characterized. They had molecular weights of 22.7, 21.6, 23.7, and 22.5 kDa, respectively and showed 37.2–42.1% sequence identity to CaBP22.8 of O. viverrini. All were detected in 2- and 4-week-old immature and mature parasites. Additionally, OvCaBP4 was found in newly excysted juveniles. Polyclonal antibodies against each isoform were generated to detect the native proteins in parasite extracts by Western blot analysis. All OvCaBPs were detected in soluble and insoluble crude worm extracts and in the excretory-secretory product, at approximate sizes of 21–23 kDa. The ion-binding properties of the proteins were analyzed by mobility shift assays with the divalent cations Ca²⁺, Mg²⁺, Zn²⁺, and Cu²+. All OvCaBPs showed mobility shifts with Ca²⁺ and Zn²⁺. OvCaBP1 showed also positive results with Mg²⁺ and Cu²⁺. As tegumental proteins, OvCaBP1, 2, and 3 are interesting drug targets for the treatment of opisthorchiasis.
Antibodies ; Blotting, Western ; Calcium-Binding Proteins ; Cations, Divalent ; Dyneins ; EF Hand Motifs ; Electrophoretic Mobility Shift Assay ; Fasciola hepatica ; Humans ; Molecular Weight ; Opisthorchiasis ; Opisthorchis ; Parasites ; Protein Isoforms

Tegumental and excretory-secretory proteins are reported as diagnostic antigens for human opisthorchiasis. Rhophilin associated tail protein1-like (OvROPN1L) protein of Opisthorchis viverrini sperm tail showed potential as a diagnostic antigen. The OvROPN1L recombinant fragments were assayed for diagnostic antigenicity for human opisthorchiasis using indirect ELISA. The strongest antigenic region was a N-terminus peptide of M1 - P56. One synthetic peptide (P1, L3-Q13) of this region showed the highest antigenicity to opisthorchiasis. Sera from other parasitic infections including Strongyloides stercoralis, hookworm, Taenia spp, minute intestinal flukes, Paragonimus spp showed lower reactivity to P1. Peptide P1 is located in the disordered N-terminus of ROPN1L supporting its suitability as linear epitope. In the Platyhelminthes the N-terminal sequence of ROPN1L is diverging with taxonomic distance further suggesting that peptide P1 has potential as diagnostic tool in the genus Opisthorchis/Clonorchis. It should be further evaluated in combination with peptides derived from other O. viverrini antigens to increase its diagnostic power.