Abstract

BackgroundFasciolosis is a zoonotic parasitic diseaseimposinga 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-gamma, 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-gamma, total IgG, and IgG2a levels. The mice that were injected with alum showed a significantly higher concentration of IL-4. Ratios of IFN-gamma/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.