Immunomodulatory effects of Diamond V Original XPC™ supplementation on immune gene expression in broilers

A study was conducted to evaluate the molecular and cellular immunomodulatory effects of Diamond V Original XPC (XPC), a broad-spectrum immune modulator, in broilers. Our lab has demonstrated that broilers fed XPC generate faster and stronger antigen-specific humoral immune responses to Newcastle Disease Virus (NDV) vaccination. One-day-old broilers were randomly assigned one of two treatments: 1.25 kg/ton XPC (T1) or control diet (T2). Birds were vaccinated against NDV at d1 (B1 strain) and d21 (LaSota strain) post-hatch. Innate and adaptive immunerelated gene expression profiles in central (thymus and bursa of Fabricius) and peripheral immune organs (spleen) were investigated at d14 and d28 post-hatch by qPCR array. Fold changes larger than 1.2 (p<0.05) between T1 and T2 were considered significant. Lymphocyte subpopulations in central and peripheral immune organs, and blood leukocytes were analyzed by flow cytometry on days 14, 21, 28, and 42 post-hatch. In the spleen, Th1 immune responses and anti-viral genes, such as IFN-γ, and its downstream genes STAT4 and NFκB, were significantly up-regulated in T1 on d14 post-hatch. In the thymus, different functional gene groups were influenced at different time points. Cytokine genes associated with lymphocyte maturation, differentiation, and proliferation, such as IL-1, IL-2, IL-8, and IL-15 were significantly up-regulated in T1 on d28 posthatch.

Genes preferentially expressed in the medulla and mature thymocytes, such as Myxovirus resistance gene 1, interferon regulatory factor-1 (IRF-1), IRF-7, and STAT1, were up-regulated in T1. Birds supplemented with XPC had significantly higher percentages of CD3+, CD4+, and CD8+ T-cells in the thymus on d28, indicating production of more mature T-cells, which was consistent with gene expression results. Results suggest that XPC supplementation primes broilers to become more immunocompetent, without compromising growth performance.

Key Words: XPC, Immunomodulation, qPCR, Spleen, Thymus