Enhancing H11 Protein-Induced Immune Protection Against Haemonchus contortus in Goats: A Nano-Adjuvant Formulation Strategy

Simple SummaryHaemonchosis, caused byHaemonchus contortus, is a major parasitic disease in ruminants. The heavy reliance on anthelmintics has exacerbated drug resistance, making vaccine development imperative. H11 protein, a dominant antigen, confers partial immune protection to the host, but its formulation with the conventional QuilA adjuvant requires periodic booster immunizations. This study aimed to develop novel nano-adjuvants to enhance protective efficacy and prolong protection duration. Findings indicated that an immunostimulating complex matrix (IMX) combined with H11 protein elicited robust humoral immunity and durable immune memory in the host.The only vaccine againstHaemonchus contortusis limited by short-lived antibody persistence and the need for frequent booster immunizations. This study leveraged the advantages of nano-adjuvants in enhancing antigen presentation and immune regulation to evaluate the efficacy of novel adjuvants (IMX, AddaS03) and the conventional QuilA combined with H11 protein. Goats were divided into four groups (IMX + H11, AddaS03 + H11, QuilA + H11, and infected control). They were immunized three times and challenged with 6000 infective third-stage larvae (iL3s) ofH. contortuson the day of the third immunization, with the experiment lasting for 98 days. The results showed that vaccination with IMX + H11 conferred the strongest protection, demonstrating 88.3% efficacy in fecal egg count (FEC) reduction and 75.8% efficacy against worm burden, followed by QuilA + H11 (85.2% FEC reduction and 68% worm burden reduction) and AddaS03 + H11 (79.4% FEC reduction and 61.3% worm burden reduction). Serum IgG analysis revealed high antibody levels in all immunized groups. Cytokine detection found that IMX + H11 significantly upregulated IL-2 and IFN-γ expression in PBMCs and TNF-α expression in splenocytes, activating Th1-type responses and immune memory. QuilA + H11 showed weaker Th1 activation, and AddaS03 + H11 faced limitations due to insufficient antibody persistence for long-term protection. These findings suggest that IMX can induce highly efficient humoral and cellular immunity, providing a new direction for the optimization ofH. contortusvaccines and suggesting the importance of nano-adjuvants for precise regulation of immune patterns.