Systems Biology behind Immunoprotection of Both Sheep and Goats after Sungri/96 PPRV Vaccination

Abstract

Immune response is a highly coordinated cascade involving all the subsets of peripheral blood mononuclear cells (PBMCs). In this study, RNA sequencing (RNA-Seq) analysis of PBMC subsets was done to delineate the systems biology behind immune protection of the vaccine in sheep and goats. The PBMC subsets studied were CD4+, CD8+, CD14+, CD21+, and CD335+ cells from day 0 and day 5 of sheep and goats vaccinated with Sungri/96 peste des petits ruminants virus. Assessment of the immune response processes enriched by the differentially expressed genes (DEGs) in all the subsets suggested a strong dysregulation toward the development of early inflammatory microenvironment, which is very much required for differentiation of monocytes to macrophages, and activation as well as the migration of dendritic cells into the draining lymph nodes. The protein-protein interaction networks among the antiviral molecules (IFIT3, ISG15, MX1, MX2, RSAD2, ISG20, IFIT5, and IFIT1) and common DEGs across PBMC subsets in both species identified ISG15 to be a ubiquitous hub that helps in orchestrating antiviral host response against peste des petits ruminants virus (PPRV). IRF7 was found to be the key master regulator activated in most of the subsets in sheep and goats. Most of the pathways were found to be inactivated in B lymphocytes of both the species, indicating that 5 days postvaccination (dpv) is too early a time point for the B lymphocytes to react. The cell-mediated immune response and humoral immune response pathways were found more enriched in goats than in sheep. Although animals from both species survived the challenge, a contrast in pathway activation was observed in CD335+ cells. IMPORTANCE Peste des petits ruminants (PPR) by PPR virus (PPRV) is an World Organisation for Animal Health (OIE)-listed acute, contagious transboundary viral disease of small ruminants. The attenuated Sungri/96 PPRV vaccine used all over India against this PPR provides long-lasting robust innate and adaptive immune response. The early antiviral response was found mediated through type I interferon-independent interferon-stimulated gene (ISG) expression. However, systems biology behind this immune response is unknown. In this study, in vivo transcriptome profiling of PBMC subsets (CD4+, CD8+, CD14+, CD21+, and CD335+) in vaccinated goats and sheep (at 5 days postvaccination) was done to understand this systems biology. Though there are a few differences in the systems biology across cells (specially the NK cells) between sheep and goats, the coordinated response that is inclusive of all the cell subsets was found to be toward the induction of a strong innate immune response, which is needed for an appropriate adaptive immune response.

Proteome Modulation in Peripheral Blood Mononuclear Cells of Peste des Petits Ruminants Vaccinated Goats and Sheep

“…The upregulation of genes of the key immune molecules like ISG15 in all cell subsets and IFIT3, MX1, and ISG15 in certain cell subsets of the sheep PBMCs was found at earlier stages (5 dpv) of PPRV vaccination ( 11 ). In goats, the elevated levels of the genes of ISG20, ISG15, IRF7, various IFITs, MX1, and MX2 was found at 5 dpv ( 11 ). The altered expression of these PBMC proteins, identified following PPRV vaccination of sheep and goats, suggests marked changes in cellular signaling pathways to modulate host responses.…”

“…ISG15, IRF7, MX1, RSAD2, and IFIT3 have been found to play a vital role in modulating immune response against the viral infection (26-33). The upregulation of genes of the key immune molecules like ISG15 in all cell subsets and IFIT3, MX1, and ISG15 in certain cell subsets of the sheep PBMCs was found at earlier stages (5 dpv) of PPRV vaccination (11). In goats, the elevated levels of the genes of ISG20, ISG15, IRF7, various IFITs, MX1, and MX2 was found at 5 dpv (11).…”

“…Sungri/96 vaccine is believed to provide protective immunity in sheep and goats for years (3). This immune response that results in the protection of hosts after vaccination is attributed to innate and both humoral and cell-mediated immunity, which, however, warrants further investigation (6)(7)(8)(9)(10)(11).…”

Changes in m6A RNA methylation of goat lung following PPRV infection

“…ISGs -ISG15, ISG20, IRF7, IFIT1, IFIT3, IFIT5, MX1, IFI6, and OAS1 whose antiviral activity has been reported in various RNA virus infections (Schneider, Chevillotte et al 2014), have also been found to be elevated in lymphocytes isolated from virulent PPRV infected goat (Wani, Sahu et al 2019) and various PBMCs subsets isolated from Sungri 96/PPRV vaccine goats (Wani, Praharaj et al 2021).…”

“…In earlier studies of host-PPRV interaction, we have reported higher expression of genes encoding different molecule species such as Interferon-Stimulated Genes (ISGs), interleukins and viral sensors involved in innate immunity following PPRV infection (Wani, Sahu et al 2019, Wani, Praharaj et al 2021). Among the immune-related processes enriched by the upregulated genes, we found that upregulated genes involved in these processes are ISGs like IFI44L, IFI6, IFIT1, IFIT2, IFIT3, IFIT5, IRF7, ISG15, ISG20, and MX1; interleukin and interleukin receptors such as IL17RA, IL18, IL1RN, IL4R, IL7R, IL10RB, IL17RB, IL1R2, IL1RL1, IL27, IL27RA, IL33, and IL6ST, and viral sensors like RIG-I (DDX58), MDA5 (IFIH1) and TLR2, TLR3, TLR4, and TLR6 (Figure 5E).…”