In Vitro and In Vivo Studies for Assessing the Immune Response and Protection-Inducing Ability Conferred by Fasciola hepatica-Derived Synthetic Peptides Containing B- and T-Cell Epitopes

Abstract

Fasciolosis is considered the most widespread trematode disease affecting grazing animals around the world; it is currently recognised by the World Health Organisation as an emergent human pathogen. Triclabendazole is still the most effective drug against this disease; however, resistant strains have appeared and developing an effective vaccine against this disease has increasingly become a priority. Several bioinformatics tools were here used for predicting B- and T-cell epitopes according to the available data for Fasciola hepatica protein amino acid sequences. BALB/c mice were immunised with the synthetic peptides by using the ADAD vaccination system and several immune response parameters were measured (antibody titres, cytokine levels, T-cell populations) to evaluate their ability to elicit an immune response. Based on the immunogenicity results so obtained, seven peptides were selected to assess their protection-inducing ability against experimental infection with F. hepatica metacercariae. Twenty-four B- or T-epitope-containing peptides were predicted and chemically synthesised. Immunisation of mice with peptides so-called B1, B2, B5, B6, T14, T15 and T16 induced high levels of total IgG, IgG1 and IgG2a (p<0.05) and a mixed Th1/Th2/Th17/Treg immune response, according to IFN-γ, IL-4, IL-17 and IL-10 levels, accompanied by increased CD62L+ T-cell populations. A high level of protection was obtained in mice vaccinated with peptides B2, B5, B6 and T15 formulated in the ADAD vaccination system with the AA0029 immunomodulator. The bioinformatics approach used in the present study led to the identification of seven peptides as vaccine candidates against the infection caused by Fasciola hepatica (a liver-fluke trematode). However, vaccine efficacy must be evaluated in other host species, including those having veterinary importance.

Identification and immunogenic potential of B cell epitopes of outer membrane protein OmpF of Aeromonas hydrophila in translational fusion with a carrier protein

“…Epitope-based vaccines have for long stood out as promising vaccine candidates against diverse pathogens (Christy et al 2012;Hurtgen et al 2012;Pan et al 2012;Kunthalert et al 2013;Rojas-Caraballo et al 2014) and have forayed their way in human clinical trials as well (Iinuma et al 2014). Other than helping to focus on and thereby narrowing down the specificity of immune response, they also leave room for chimera generation including multiple epitopes from same as well as different and slightly more immunogenic antigens.…”

Transcriptome profiling of gene expression during immunisation trial against Fasciola hepatica: identification of genes and pathways involved in conferring immunoprotection in a murine model

“…A previous study by our group led to identifying seven F. hepatica cathepsin B and amoebapore-derived peptides containing B- and T-cell epitopes as promising vaccine candidates [29]. Briefly, from partial publically available information in databases concerning F. hepatica protein amino acid sequences, target-proteins were selected in line with the following criteria: proteins having a signal peptide sequence as predicted by SignalP 3.0 server, freely available at http://www.cbs.dtu.dk/services/SignalP-3.0/ [31] and proteins lacking a trans-membrane domain as predicted by the TMHMM v2.0 server.…”

“…The presence of specific antibodies raised against F. hepatica was also detected in all the mice infected with F. hepatica metacercariae according to the methodology previously described [29]. …”

“…A previous study by our group involving the use of bioinformatics tools showed the protection-inducing ability of F. hepatica cathepsin B and amoebapore-derived B- and T-cell epitopes which had been chemically-synthesised and selected as vaccine candidates according to their induced immune response in a murine model, reaching up to 66.7% protection after immunisation [29]. According to the results obtained in the above mentioned article, where we found reduction in hepatic damage and increase of survival rates, in the present study we hypothesised that a combination of peptides with different induced-immune responses could act in a synergic way in order to improve the immunoprotection in mice.…”

Antidiabetic, cytotoxic, antioxidant and antitrematodal medicinal efficacy of polar and non-polar phytochemicals of Balanites aegyptiaca Del.

“…The experiments were performed in triplicates using RPMI media contained antibiotics [15]. Phosphate buffer (pH 7.4) was used for rinsing the worms prior hosting in the media; two worms of S. mansoni were hosted in 1 mL media and 2 worms of F. gigantica were hosted in 5 mL media.…”