Transcription profiles of the responses of chicken bursae of Fabricius to IBDV in different timing phases

Abstract

Background: Infectious bursal disease virus (IBDV) infection causes immunosuppression in chickens and increases their susceptibility to secondary infections. To explore the interaction between host and IBDV, RNA-Seq was applied to analyse the transcriptional profiles of the responses of chickens' bursas of Fabricius in the early stage of IBDV infection.

Results: The results displayed that a total of 15546 genes were identified in the chicken bursa libraries. Among the annotated genes, there were 2006 and 4668 differentially expressed genes in the infection group compared with the mock group on day 1 and day 3 post inoculation (1 and 3 dpi), respectively. Moreover, there were 676 common up-regulated and 83 common down-regulated genes in the bursae taken from the chickens infected with IBDV on both 1 and 3 dpi. Meanwhile, there were also some characteristic differentially expressed genes on 1 and 3 dpi. On day 1 after inoculation with IBDV, host responses mainly displayed immune response processes, while metabolic pathways played an important role on day three post infection. Six genes were confirmed by quantitative reverse transcription-PCR.

Conclusions: In conclusion, the differential gene expression profile demonstrated with RNA-Seq might offer a better understanding of the molecular interactions between host and IBDV during the early stage of infection.

Keywords: Bursa of Fabricius; Chicken; Infectious bursal disease virus; RNA-Seq; Transcription profiles.

Fig. 1

Quantification of the infectious bursal disease virus (IBDV) VP2 gene levels in the bursae of Fabricius in the mock group and the infection group by real-time PCR. The data were expressed as the average ratio of IBDV/β-actin. **Indicates P < 0.01 when samples taken from day 1 postinfection in the infection group were compared with those from day 3 in the infection group

Fig. 2

Identification and expression of the bursae collected from chickens inoculated with IBDV on day 1 and day 3. a The Venn diagram showing unique and common differentially expressed genes of the bursae collected from the infection group on day 1 and day 3 postinoculation with IBDV compared with the mock group. b The Venn diagram showing unique and common upregulated expressed genes, of which the fold changes were ≥ 2. c The Venn diagram showing unique and common downregulated expressed genes, of which the fold changes were ≤ 0.5

Fig. 3

Expression profiles (heat maps) of SDE genes between days 1 and 3 post infection with IBDV (day 1: sample 1–3; day 3: 4–6). The color in the heat-map represents the normalised isotig number. The color in the heat-map represents gene expression changes. Red indicates high gene expression activity; green indicates low gene expression and black indicates no activity. SDE gene clusters were labeled in the left of the heat-map line