Development of a novel squalene/α-tocopherol-based self-emulsified nanoemulsion incorporating Leishmania peptides for induction of antigen-specific immune responses.

Vaccination has emerged as the most effective strategy to confront infectious diseases, among which is leishmaniasis, that threat public health. Despite laborious efforts there is still no vaccine for humans to confront leishmaniasis. Multi-epitope protein/peptide vaccines present a number of advantages, however their use along with appropriate adjuvants that may also act as antigen carriers is considered essential to overcome subunit vaccines' low immunogenicity. In the present study, a stable self-emulsified nanoemulsion was developed and double-adjuvanted with squalene and α-tocopherol. The prepared nanoemulsion droplets exhibited low cytotoxicity in a certain range of concentrations, while they were efficiently taken up by macrophages and dendritic cells in vitro as well as in vivo in secondary lymphoid organs. To further characterize nanoformulation's potent antigen delivery capability, three multi-epitope Leishmania peptides were incorporated into the nanoemulsion. Peptide encapsulation resulted in dendritic cells' functional differentiation characterized by elevated levels of maturation markers and intracellular cytokine production. Intramuscular administration of the nanoemulsion incorporating Leishmania peptides induced antigen-specific spleen cell proliferation as well as elicitation of CD4+ central memory cells, supporting the potential of the developed nanoformulation to successfully act also as an antigen delivery vehicle and thus encouraging further preclinical studies on its vaccine candidate potency.

Effect of dietary incorporation of a multi-strain probiotic on growth performance and health status in rainbow trout (Oncorhynchus mykiss).

Dietary supplementation with a multi-strain probiotic containing Bacillus subtilis, Enterococcus faecium, Pediococcus acidilactici and Lactobacillus reuteri has been examined for its effects on growth performance, intestinal microbiota, non-specific immune response and antioxidant status of rainbow trout. Three groups of sub-adult trout were stocked into experimental tanks. A commercial diet was used as control, while the other two groups received diets supplemented with the multi-strain probiotic at levels of 1 and 5 g kg(-1) diet. The fish were fed to apparent satiation three times daily for 8 weeks. Dietary probiotic at 1 g kg(-1) diet improved (P < 0.05) growth and feed efficiency compared to control diet. Lactic acid bacteria loads were higher in probiotic fed fish at both inclusion levels compared to control; however, Enterobacteriaceae, Coliforms and Aeromonas spp. were similar between groups. Dietary probiotics decreased (P < 0.05) malondialdehyde formation on day 0 compared to control fish but not on day 5 of storage. Probiotics also increased (P < 0.05) the activity of glutathione-based enzymes. Serum lysozyme levels were similar among dietary treatments. Probiotic supplementation at 1 g kg(-1) diet reduced serum nitric oxide levels compared to control. In conclusion, dietary probiotics at the level of 1 g kg(-1) of diet exerted both a growth promoting and antioxidant protective activity.