Background and Aim: Cystic echinococcosis (CE) is a widespread parasitic disease caused by Echinococcus granulosus tapeworm infect different intermediate hosts including sheep, cattle, and camels. The intermediate host's immune response to the hydatid cyst is still conflict and complex. The current study was designed to evaluate the immune response in sera of hydatid naturally infected sheep, cattle, and camels in the form of features of inflammatory cell infiltrations, levels of Th1 and Th2 cytokines, besides the humoral specific immunoglobulin G (IgG) responses.

Materials and Methods: Thirty-nine sheep, 74 cattle, and 79 camels' sera were collected and considered as CE naturally infected and ten samples from each species were graded as non-infected. Lung specimens were collected for histopathological examination. The quantitative concentrations of tumor necrosis factor-α, interleukin (IL)-6, IL-4, and IL-10 were determined. Different antigens were prepared from hydatid cyst; hydatid cyst fluid of lung origin hydatid cyst fluid of liver origin, hydatid cyst protoscoleces of lung origin (HCP-g), hydatid cyst protoscoleces of liver origin , hydatid cyst germinal layer of lung origin, and hydatid cyst germinal layer of liver origin; and characterized by gel electrophoresis and Western blotting analysis. The total specific IgG level against E. granulosus infection was measured using an indirect enzyme-linked immunosorbent assay.

Results: The results indicated that the cellular immune response in the infected tissues was characterized by inflammatory cell penetration. The pro-inflammatory Th1 cytokine profile was predominant in infected animals in comparison with non-infected ones. However, the humoral immune response was seen as a high level of IgG in infected animals. The presented data approved that the HCP-g antigen could be considered as a delegate antigen for all other prepared antigens with an immunoreactive band at molecular weights 32 kDa.

Conclusion: This study provides a fundamental insight into the events that manipulate cellular and humoral immune profiles in an intermediate host; sheep, cattle, and camel that naturally infected with CE. Hence, it was concluded that CE is a constant disease and confirm the reactivity Th1 in combating hydatid cyst. Besides, it could lead to the activation of the humoral immune response in the form of a high level of IgG.

Keywords: cell-mediated immune response, humoral immune response, hydatidosis.