Comparative analysis of innate immune response following in vitro stimulation of sheep and goat peripheral blood mononuclear cells with bluetongue virus – serotype 23

Abstract

Bluetongue is an infectious disease caused by bluetongue virus (BTV), which affects sheep, goat, cattle and certain wild ruminants. However severe clinical signs are usually seen with significant mortality in sheep than cattle and goat. To date, comparative studies on innate immune responses of sheep and goat infected with BTV is lacking. In this study, we compared the innate immune response of sheep and goat by infecting the peripheral blood mononuclear cells (PBMCs) with BTV serotype 23. In our study, we observed that sheep PBMCs supports higher virus replication than goat PBMCs. To delineate the role of innate immune response in differential viral replication observed in this study, we examined TLR3 (Receptor for dsRNA virus) mRNA expression and cytokine profiles (IL-1β, Il-6, IL-8, Il-10, IL-12p40, TNF-α, IFN-γ and IFN-α) following Poly I:C (TLR3 ligand) stimulation and BTV 23 infection. In our present study, sheep PBMCs had significantly higher TLR3 mRNA levels, TLR3 specific ligand (Poly I:C) stimulation resulted in increased levels of IFN-γ at transcriptional and translational levels along with IL-8 and IL-10 at transcriptional levels. Whereas, the levels of TNF-α was higher in goat PBMCs at transcriptional levels. BTV infected sheep PBMCs expressed significantly higher levels of IFN-γ at transcriptional and translational levels along with IL-6, IL-8 and IL-10 at transcriptional levels. Whereas the expression levels of TNF-α and IFN-α at transcriptional and translational levels were significantly high in goat PBMCs. To examine the potential factor for consistent increase in the expression of TNF-α, we sequenced the promoter region of TNF-α and identified a total of five single nucleotide polymorphisms (SNP) and one indel in goat TNF-α promoter region. Luciferase assay for transcriptional activity of the promoter showed that goat TNF-α has significantly enhanced transcriptional activity in comparison with sheep TNF-α promoter. Altogether, our data suggests that the expression levels of TNF-α and IFN-α and/or IL-10 plays crucial role in replication of BTV 23.

Transcriptome analysis reveals common differential and global gene expression profiles in bluetongue virus serotype 16 (BTV-16) infected peripheral blood mononuclear cells (PBMCs) in sheep and goats

“…Antibodies to the virus (BTV) are common in cattle, buffaloes and goats, but the clinical disease has not been reported in these animals [24]. Recently, the RNA levels of the BTV in the PBMC culture supernatant showed, sheep PBMCs supports more replication of the virus compared to goats [18]. However, the severity of the disease in the sensitive hosts depends on the strain of the virus, breed, immune status of the animal, virulence of the virus, other host factors etc.…”

“…Also, the viral pathogenesis of BTV resulting in presence or absence of clinical disease among different hosts is not clearly understood and both, the virus and host species are thought to be of importance. PBMCs were used in vitro to study the innate immune responses in sheep and goats in response to BTV infection [18]. Recently, global transcriptome analysis was used to understand the molecular events of host virus interactome in PPRV [19], Measles virus [20], [21] and Rinderpest virus [21] infections.…”

Pathological Characterization Of IFNAR(-/-) Mice Infected With Bluetongue Virus Serotype 4

“…Furthermore, in vitro BTV infections of peripheral blood mononuclear cells (PBMC) from a number of ruminant species resulted in the production of inflammatory cytokines. BTV infection of PBMC from bovine 39, sheep and goats 41 induced IL-1, 6, 8, and 10, IFN-γ, TNF and iNOS, although these studies used different experimental designs and BTV serotypes, making correlations among species difficult.…”

Dual Modulation of Type I Interferon Response by Bluetongue Virus

“…Together with its ability to modulate IFN synthesis (38), BTV would then ensure a powerful inhibition of the cellular response. Several studies have suggested that IFN-I is an important factor to limit BTV replication and dissemination and control infection (52)(53)(54). By inhibiting both IFN-I synthesis and signaling pathways, BTV would then promote the establishment of an infection.…”