LAUSR

BackgroundFasciolosis is a zoonotic parasitic disease imposing a heavy load of livestock losses worldwide.PurposeWe aimed to evaluate immune-stimulatory effects of naloxone (NLX), an opioid receptor antagonist, in combination with alum in mice vaccinated with excretory–secretory antigens (E/S) of Fasciola hepatica.Methods8-week-old female BALB/c mice were subcutaneously vaccinated using E/S antigens of F. hepatica. Experimental groups (14 mice per group) included: vaccine (E/S antigen), alum vaccine (E/S antigen plus alum), NLX vaccine (E/S antigen plus NLX), and alum–NLX vaccine (E/S antigen plus a mixture of alum–NLX). The control group was infused with PBS. Lymphocyte proliferation and the levels of IFN-γ, IL-4, IgG2a, IgG1, and total IgG were measured.ResultsMice vaccinated with NLX or alum–NLX adjuvants showed significantly higher rates of lymphocyte proliferation, IFN-γ, total IgG, and IgG2a levels. The mice that were injected with alum showed a significantly higher concentration of IL-4. Ratios of IFN-γ/Il-4 and IgG2a/IgG1 were significantly higher in the NLX and alum–NLX groups in comparison with the groups vaccinated either with alum or without any adjuvant. A significantly higher protection rate (62.5%) was seen in mice vaccinated with the alum–NLX adjuvant compared to the other groups.ConclusionNLX can be effective in conferring cellular immunity and protection against F. hepatica. It is recommended to consider this agent as a potential adjuvant in vaccines against fasciolosis.