BACKGROUND

As a natural host of , buffalo is widely infected by . Its impact on buffalo production has caused great losses to the husbandry sector, and repeat infection is non-negligible. In buffaloes experimentally infected with , primary and secondary infection have yielded the same rate of fluke recovery, indicating a high susceptibility of buffalo to , which contributes to the high infection rate. Determining the immunological mechanism of susceptibility will deepen the understanding of the interaction between and buffalo. Here, we explored the immune response of buffaloes against primary and secondary infection, with a focus on cytokines' dynamics explored through serum cytokine detection.

METHODS

Buffaloes were assigned to three groups: group A (noninfected,  = 4), group B (primary infection,  = 3), and group C (secondary infection,  = 3). Group B was infected via oral gavage with 250 viable metacercariae, and group C was infected twice with 250 metacercariae at an interval of 4 weeks. The second infection of group C was performed simultaneously with that of group B. Whole blood samples were collected pre-infection (0 weeks) and at 1-6, 10, and 12  weeks after that. The serum levels of seven cytokines (IFN-γ, IL-4, IL-5, IL-10, IL-13, TGF-β, and IL-17) were simultaneously determined using ELISA and further analyzed.

RESULTS

In the present study, no significant changes in Th1-type cytokines production were detected in early infection, both in primary and secondary infections, while the Th2-type response was strongly induced. A comparison of primary and secondary infection showed no significant difference in the cytokine secretion, which may indicate that the re-infection at 4 weeks after primary infection could not induce a robust adaptive immune response. The full extent of interaction between buffalo and in re-infection requires further study.