Liver fluke vaccines: Vaccination Against Fasciolosis by a Multivalent Vaccine of Recombinant Stage-Specific Antigens

Fasciola\u27s excretory-secretory material comprises chiefly cathepsin B and cathepsin L. These cysteine proteases are proposed as major mediators of parasitism, and are considered targets for vaccination. In order to assess the vaccine efficacy of these enzymes, single and multivalent recombinant protein vaccinations of adult-stage F. hepatica cathepsin L5, metacercarial-stage F. gigantica cathepsin L1 g and juvenile-stage F. hepatica cathepsin B were analysed in rats against F. hepatica challenge infection. The protective efficacy of anti-fluke vaccines was evaluated in terms of parasitological parameters (recovered fluke burden, fluke body size and wet weight) and pathological changes (liver damage score) in rats. The rats vaccinated with recombinant proteins were shown to have significantly fewer and smaller flukes than the control rats. A maximum protection of 83% was seen in the group vaccinated with a combination of cathepsin B and cathepsin L5

Proteomics and in silico approaches to extend understanding of the glutathione transferase superfamily of the tropical liver fluke Fasciola gigantica

Fasciolosis is an important foodborne, zoonotic disease of livestock and humans, with global annual health and economic losses estimated at several billion US$. Fasciola hepatica is the major species in temperate regions, while F. gigantica dominates in the tropics. In the absence of commercially available vaccines to control fasciolosis, increasing reports of resistance to current chemotherapeutic strategies and the spread of fasciolosis into new areas, new functional genomics approaches are being used to identify potential new drug targets and vaccine candidates. The glutathione transferase (GST) superfamily is both a candidate drug and vaccine target. This study reports the identification of a putatively novel Sigma class GST, present in a water-soluble cytosol extract from the tropical liver fluke F. gigantica. The GST was cloned and expressed as an enzymically active recombinant protein. This GST shares a greater identity with the human schistosomiasis GST vaccine currently at Phase II clinical trials than previously discovered F. gigantica GSTs, stimulating interest in its immuno-protective properties. In addition, in silico analysis of the GST superfamily of both F. gigantica and F. hepatica has revealed an additional Mu class GST, Omega class GSTs, and for the first time, a Zeta class member

Profiles of Small Non-Coding RNAs in Schistosoma japonicum during Development

Schistosomiasis, a debilitating disease, caused by agents of the genus Schistosoma afflicts more than 200 million people worldwide. Schistosomes could serve as an interesting model to explore gene regulation due to its evolutional position, complex life cycle and sexual dimorphism. We previously indicated that sncRNA profile in the parasite S. japonicum was developmentally regulated in hepatic and adult stages. In this study, we systematically investigated mircoRNA (miRNA) and endogenous siRNA (endo-siRNA) profile in this parasite in more detailed developmental stages (cercariae, lung-stage schistosomula, separated adult worms, and liver tissue-trapped eggs) using high-throughput RNA sequencing technology. We observed that the ratio of miRNAs to endo-siRNAs was dynamically changed throughout different developmental stages of the parasite. MiRNAs were expressed dominantly in cercariae, while endo-siRNAs accumulated in adult female worms and hepatic eggs. We demonstrated that miRNAs were mostly derived from intergenic regions whereas siRNAs were mostly derived from transposable elements. We also annotated miRNAs and siRNAs with stage- and gender- biased expression. Our findings would facilitate to understand the gene regulation mechanism of this parasite and discover novel targets for anti-parasite drugs

An integrated bioinformatics analysis reveals divergent evolutionary pattern of oil biosynthesis in high- and low-oil plants

Seed oils provide a renewable source of food, biofuel and industrial raw materials that is important for humans. Although many genes and pathways for acyl-lipid metabolism have been identified, little is known about whether there is a specific mechanism for high-oil content in high-oil plants. Based on the distinct differences in seed oil content between four high-oil dicots (20~50%) and three low-oil grasses (<3%), comparative genome, transcriptome and differential expression analyses were used to investigate this mechanism. Among 4,051 dicot-specific soybean genes identified from 252,443 genes in the seven species, 54 genes were shown to directly participate in acyl-lipid metabolism, and 93 genes were found to be associated with acyl-lipid metabolism. Among the 93 dicot-specific genes, 42 and 27 genes, including CBM20-like SBDs and GPT2, participate in carbohydrate degradation and transport, respectively. 40 genes highly up-regulated during seed oil rapid accumulation period are mainly involved in initial fatty acid synthesis, triacylglyceride assembly and oil-body formation, for example, ACCase, PP, DGAT1, PDAT1, OLEs and STEROs, which were also found to be differentially expressed between high- and low-oil soybean accessions. Phylogenetic analysis revealed distinct differences of oleosin in patterns of gene duplication and loss between high-oil dicots and low-oil grasses. In addition, seed-specific GmGRF5, ABI5 and GmTZF4 were predicted to be candidate regulators in seed oil accumulation. This study facilitates future research on lipid biosynthesis and potential genetic improvement of seed oil content

A Portrait of the Transcriptome of the Neglected Trematode, Fasciola gigantica—Biological and Biotechnological Implications

Fasciola gigantica (Digenea) is an important foodborne trematode that causes liver fluke disease (fascioliasis) in mammals, including ungulates and humans, mainly in tropical climatic zones of the world. Despite its socioeconomic impact, almost nothing is known about the molecular biology of this parasite, its interplay with its hosts, and the pathogenesis of fascioliasis. Modern genomic technologies now provide unique opportunities to rapidly tackle these exciting areas. The present study reports the first transcriptome representing the adult stage of F. gigantica (of bovid origin), defined using a massively parallel sequencing-coupled bioinformatic approach. From >20 million raw sequence reads, >30,000 contiguous sequences were assembled, of which most were novel. Relative levels of transcription were determined for individual molecules, which were also characterized (at the inferred amino acid level) based on homology, gene ontology, and/or pathway mapping. Comparisons of the transcriptome of F. gigantica with those of other trematodes, including F. hepatica, revealed similarities in transcription for molecules inferred to have key roles in parasite-host interactions. Overall, the present dataset should provide a solid foundation for future fundamental genomic, proteomic, and metabolomic explorations of F. gigantica, as well as a basis for applied outcomes such as the development of novel methods of intervention against this neglected parasite

Influence of promoter, gene copy number, and preexisting immunity on humoral and cellular responses to a vectored antigen delivered by a Salmonella enterica vaccine

Attenuated Salmonella strains are currently in production as vaccines for protection of animals against salmonellosis. Such commercial strains offer the potential to deliver heterologous antigen to protect animals against other diseases. One vaccine strain, attenuated Salmonella enterica serovar Typhimurium (STM-1), was tested for the ability to deliver ovalbumin and to induce immune responses in mice. Two vaccine trials were performed testing the influence of promoter choice, the location of the encoding DNA (plasmid or chromosome), and the effect of preexisting homologous or heterologous immunity. The results demonstrated that humoral and T-cell responses were induced from either of two promoters, from either the plasmid or the chromosome, and that preexposure to the empty homologous vector, STM-1, or the heterologous vector, S. enterica serovar Enteritidis, had no detrimental effect on subsequent antigen-specific responses. In the case of homologous preexposure, responses were generally greater, and this was correlated with an increased uptake of Salmonella by macrophages in vitro after opsonization with immune sera

Induction of crossover by introduction of aro554:Tn10 into Salmonella chromosome

One of the ancient methods for the generation of bacterial mutants was to insert the composite transposable elements (e.g. Tn10) flanked by desired gene sequences, into the bacterial chromosome. This mechanism of DNA integrating into a chromosome can sometimes not only lead to the creation of desired mutants but also induced other recombination event within the chromosome. Several studies have reported alterations such as deletion, insertion, inversion and both deletion/inversion in the bacterial chromosome due to the insertion of composite transposable elements. In this study it has been found that a Tn10 mutagenesis event not only leads to the inactivation of desired gene (?aorA), and consequential deletion of other genes upstream of aroA and insertion of IS10, also has resulted in a largescale chromosomal rearrangement in the Salmonella Typhimurium chromosome. This rearrangement consists of exchange of genetic material between the 10 minute and the 19 minute on a circular chromosomal map (approximately 440 kbps), possibly due to crossover between the two regions. Results from this study are the first evidence of such a large scale rearrangement in the bacterial genome due to the insertion of transposable elements