Characterization and localization of Opisthorchis viverrini fructose-1,6-bisphosphate aldolase

Molecular characterization and immune efficacy of fructose-1,6-bisphosphate aldolase from Haemaphysalis longicornis (Acari: Ixodidae)

BACKGROUND

Ticks are obligate hematophagous ectoparasites that transmit a variety of pathogens to humans, wildlife and domestic animals. Vaccination is an effective and environmentally friendly method for tick control. Fructose-1,6-bisphosphate aldolase (FBA) is an important glycometabolism enzyme that is a candidate vaccine against parasites. However, the immune protection of FBA in ticks is unclear. METHODS AND RESULTS: The 1092-bp open reading frame (ORF) of FBA from Haemaphysalis longicornis (HlFBA), encoding a 363-amino acid protein, was cloned using PCR methodology. The prokaryotic expression vector pET32a(+)-HlFBA was constructed and transformed into cells of Escherichia coli BL21(DE3) strain for protein expression. The recombinant HlFBA protein (rHlFBA) was purified by affinity chromatography, and the western blot results suggested that the rHlFBA protein was immunogenic.

RESULTS

Results of the enzyme-linked immunosorbent assay showed that rabbits immunized with rHlFBA produced a humoral immune response specific to rHlFBA. A tick infestation trial indicated that, compared to the ticks in the histidine-tagged thioredoxin (Trx) group, the engorged tick weight and oviposition of female ticks and egg hatching rate of those in the rHlFBA group was reduced by 22.6%, 45.6% and 24.1%, respectively. Based on the cumulative effect of the these three parameters, the overall immune efficacy of rHlFBA was estimated to be 68.4%.

CONCLUSIONS

FBA is a candidate anti-tick vaccine that can significantly reduce the engorged tick weight, oviposition, and egg hatching rate. The use of enzymes involved in glucose metabolism is a new strategy in the development of anti-tick vaccines.

Characterization of Fructose-1,6-Bisphosphate Aldolase 1 of Echinococcus multilocularis

Glycolysis is one of the important ways by which Echinococcus multilocularis acquires energy. Fructose-1, 6-bisphosphate aldolase (FBA) plays an important role in this process, but it is not fully characterized in E. multilocularis yet. The results of genome-wide analysis showed that the Echinococcus species contained four fba genes (FBA1-4), all of which had the domain of FBA I and multiple conserved active sites. EmFBA1 was mainly located in the germinal layer and the posterior of the protoscolex. The enzyme activity of EmFBA1 was 67.42 U/mg with K_m and V_max of 1.75 mM and 0.5 mmol/min, respectively. EmFBA1 was only susceptible to Fe³⁺ but not to the other four ions (Na⁺, Ca²⁺, K⁺, Mg²⁺), and its enzyme activity was remarkably lost in the presence of 0.5 mM Fe³⁺. The current study reveals the biochemical characters of EmFBA1 and is informative for further investigation of its role in the glycolysis in E. multilocularis.

Proteomic analysis of adult Schistosoma mekongi somatic and excretory-secretory proteins

Schistosoma mekongi is a causative agent of human schistosomiasis. There is limited knowledge of the molecular biology of S. mekongi and very few studies have examined drug targets, vaccine candidates and diagnostic biomarkers for S. mekongi. To explore the biology of S. mekongi, computational as well as experimental approaches were performed on S. mekongi males and females to identify excretory-secretory (ES) proteins and proteins that are differentially expressed between genders. According to bioinformatic prediction, the S. mekongi ES product was approximately 4.7% of total annotated transcriptome sequences. The classical secretory pathway was the main process to secrete proteins. Mass spectrometry-based quantification of male and female adult S. mekongi proteins was performed. We identified 174 and 156 differential expression of proteins in male and female worms, respectively. The dominant male-biased proteins were involved in actin filament-based processes, microtubule-based processes, biosynthetic processes and homeostatic processes. The major female-biased proteins were related to biosynthetic processes, organelle organization and signal transduction. An experimental approach identified 88 proteins in the S. mekongi secretome. The S. mekongi ES proteins mainly contributed to nutrient uptake, essential substance supply and host immune evasion. This research identifies proteins in the S. mekongi secretome and provides information on ES proteins that are differentially expressed between S. mekongi genders. These findings will contribute to S. mekongi drug and vaccine development. In addition, the study enhances our understanding of basic S. mekongi biology.

Liver fluke infection and cholangiocarcinoma: a review

Parasites are significant groups for carcinogenesis among which liver flukes, including Opisthorchis viverrini and Clonorchis sinensis, are typical representatives causing cholangiocarcinoma (CCA), the second most common primary hepatic malignancy with dismal prognosis. O. viverrini is prevalent in Southeast Asia, infecting 10 million people while C. sinensis has a wider distribution in East Asia and several Southeast Asian countries, affecting more than 35 million people's health. These two worms have some common characteristics and/or discrepancies in life cycle, genome, and transcriptome. As hot spots in recent years, genome and transcriptome research has extracted numerous novel fluke worm-derived proteins, which are excellent for carcinogenic exploration. However, just a handful of these studies have focused on the metabolic pathway. In this study, the main mechanisms of carcinogenesis of both worms, in terms of mechanical damage, metabolic products and immunopathology, and other possible pathways, will be discussed in detail. This review retrospectively describes the main traits of C. sinensis and O. viverrini, their molecular biology and core carcinogenic mechanisms in a contrast pattern.