Effect of the biosurfactant surfactin on the adjuvant potential of nanoencapsulated Minthostachys verticillata essential oil

VANCOLLI ML; CECCHINI ME; MONTIRONI ID; ARSAUTE S; AZCURRA N; BELLINGERI R; GONZALEZ PEREYRA ML; CARIDDI LN

Congreso; Reunión conjunta SAIC SAI&FAIC SAFIS; 2022

In previous studies, the adjuvant effect of the Minthostachys verticillata essential oil (EO) was demonstrated by increase in the immunogenicity of different antigens. The aim of this work was to evaluate the effect of the biosurfactant surfactin, isolated from Baccillus subtilis, on the adjuvant potential of nanoemulsified M. verticillata EO (NEOS). The NEOS was synthetized with 20% v/v of EO, 1% of surfactin (0.1 mg/mL), 1% of Tween 80 and 78 v/v of distillated water; the nanodroplet size was 143 nm (PDI=0,21). The vaccine formulations were performed with inactivated enterotoxigenic Escherichia coli (ETEC) as antigen (1x109 UFC/mL), with either safe concentrations of NEOS (1; 0.75 and 0.5 mg/mL), incomplete Freund's adjuvant (IFA) (50%), EO (1 mg/mL), surfactant mixture (Tween80/surfactin 1mg/mL) or saline solution. Saline-treated animals were included as a negative control. Mice were divided into eight groups of four animals each and vaccines were administrated subcutaneously on days 1, 14, 28 and 42. Animals were kept under controlled temperature, provided ad libitum access to food and water and were sacrificed 7 days after the last inoculation. For each group, a pool of sera was obtained by centrifugation and anti-ETEC IgG titers were determined through the indirect ELISA method. Assays were performed by triplicate. The results showed that EO administered as adjuvant increased the IgG titers compared with ETEC group (p