Pre- and post-challenge effects of essential oils (EO) on mRNA expression of antiviral and pro-inflammatory pathways genes on chicken macrophages infected with IBDV

A study was conducted to assess the pre and post-challenge effects of a single (Lippia origanoides)(Lo), Rosmarinus officinalis)(Ro) or blend of Lo and Ro of essential oils (EO) supplementation on innate immune response in chicken macrophages infected with Infectious Bursal Disease Virus (IBDV). Methods: Chicken macrophages (HD-11) cell line were cultured by triplicate at a concentration of 5x105 cells / well in plates of 24 wells. Macrophages were divided into five groups: 1. Negative control (No virus, no EOs); 2. Positive control (virus, no EOs); 3. No virus + EO (Lo); 4. No virus + EO (Ro); 5. No virus + EO (Lo + Ro); the macrophages received media supplemented with 50 ppm of Lo (group 3) or with 10-ppm Lo (group 5) and 100 Ro (groups 4 and 5). After 24 h of culture, cell were inoculated with a live vaccine of IBDV (ST-12) with a MOI=1 (Groups 2, 3, 4 and 5). Following of 1 h of virus absorption, the macrophages received again media supplemented with the same EO concentrations than before the challenge. This study evaluates periods of time 0, and 24 hours pre-infection and 0, 6 and 12 h post-infection (p.i). The research tested the effect of EOs single or blended supplementation on chicken macrophages gene expression of toll-like receptor 3, MDA5, cytokines IL-1β, IL-6, IL-12, IL-10, IRF-7, IFN-β, OAS and PKR as indicators of immunological cell activation during virus infection. IBDV virus was quantified and detected in chicken macrophages and supernatant using quantitative RT-PCR with SYBR green dye. An ANOVA model was calculated to determine the effect of Treatment group, gene and Time on the natural logarithm of CT values. Results: All groups with EO showed significant (P < 0.05) effect on virus load, decreasing it when compared with the positive control; however it was more significant with Ro EO (P < 0.001). Similar and correlated with virus infection EO affected significantly (P <0.05) the expression of IL-1β, IL-6, IL-12, IL-10, IRF-7, IFN-β, OAS and PKR genes in the pre-infection stage and the first hour post infection. Conclusion: The supplementation with a single or blend EO shown to reduce virus replication and enhance the innate immunity and correlates with both pro-inflammatory and antiviral pathways chicken macrophages.