The Tip Region on VP2 Protein of Bluetongue Virus Contains Potential IL-4-Inducing Amino Acid Peptide Segments

Abstract

Bluetongue is an infectious viral hemorrhagic disease of domestic and wild ruminants that has a considerable economic impact on domestic ruminants. There are currently at least 29 serotypes of bluetongue virus (BTV) in the world. Noteworthily, the pathogenesis among BTV serotypes is different, even in the same animal species. In this study, BTV2/KM/2003 and BTV12/PT/2003 were used to investigate the differential immunological effects on bovine peripheral blood mononuclear cells (PBMCs). The BTV viral load and the expression of cytokine messenger RNA (mRNA) in PBMCs were measured by fluorescence-based real-time reverse-transcription PCR (qRT-PCR). The immunofluorescence assay (IFA) was applied to detect BTV signals in monocyte-derived macrophages (MDMs). The SWISS-MODEL and IL-4pred prediction tools were used to predict the interleukin 4 (IL-4)-inducing peptides in BTV-coat protein VP2. Synthetic peptides of VP2 were used to stimulate PBMCs for IL-4-inducing capability. This study demonstrated that the cytokine profiles of BTV-induced PBMCs were significantly different between BTV2/KM/2003 and BTV12/PT/2003. BTV2 preferentially activated the T helper 2 (Th2) pathway, represented by the early induction of IL-4, and likely fed back to inhibit the innate immunity. In contrast, BTV12 preferentially activated the innate immunity, represented by the induction of tumor necrosis factor -α (TNF-α) and interleukin 1 (IL-1), with only minimal subsequent IL-4. The BTV nonstructural protein 3 antibody (anti-BTV-NS3) fluorescent signals demonstrated that monocytes in PBMCs and MDMs were the preferred targets of BTV replication. Bioinformatics analysis revealed that the capability to induce IL-4 was attributed to the tip region of the VP2 protein, wherein a higher number of predicted peptide segments on BTVs were positively correlated with the allergic reaction reported in cattle. Synthetic peptides of BTV2-VP2 induced significant IL-4 within 12–24 h post-infection (hpi) in PBMCs, whereas those of BTV12 did not, consistent with the bioinformatics prediction. Bovine PBMCs and synthetic peptides together seem to serve as a good model for pursuing the BTV-induced IL-4 activity that precedes the development of an allergic reaction, although further optimization of the protocol is warranted.

The Construction and Immunogenicity Analyses of a Recombinant Pseudorabies Virus with Senecavirus A VP2 Protein Coexpression

“…In this study, the levels of IL-2 and IFN-γ were similar in both vaccine groups, while the IL-4 level in the rPRV-XJ-ΔTK/gE/gI-VP2 group was slightly higher than that in the rPRV-XJ-ΔTK/gE/gI group. It has been reported that the VP2 protein of bluetongue virus (BTV) contains potential IL-4-inducing amino acid peptide segments; however, this induction effect of SVV VP2 needs further investigation ( 37 ). In addition, in the rPRV-XJ-ΔTK/gE/gI-VP2 group, inactivated SVA stimulated the proliferation of splenic lymphocytes, but this effect was not observed in the rPRV-XJ-ΔTK/gE/gI group.…”

Monitoring longitudinal immunological responses to bluetongue virus 17 in experimentally infected sheep

“…BTV-1 and BTV-8 are the most commonly studied in these models ( Bitew et al., 2019 ; Ruscanu et al., 2012 ; Sánchez‐Cordón et al. 2015 ; Melzi et al., 2016 ; Rojas et al., 2017 ; Ratinier et al., 2016 ; Drolet et al., 2015 ; Breard et al., 2015 ), however BTV-2, 4, 9, 10, 12, 16, and 23 have also been evaluated using systems including human cell culture, mouse models and sheep infections ( Bitew et al., 2019 ; Ruscanu et al., 2012 ; Breard et al., 2015 ; Putty et al., 2019 ; Yang et al., 2020 b, Dhanasekaran et al., 2013 ). Understanding BTV infections has been complicated by the use of several model systems and BTV serotypes, making comprehensive conclusions about the impact of BTV immune responses challenging.…”

“…The Th2 response has been shown to be induced upon BTV infection ( Sánchez‐Cordón et al. 2013 ; Yang et al., 2020 b; Rodríguez-Martín et al., 2021 ; Kopanke et al., 2020 ). IL-4 has been shown to be specifically induced by the BTV viral protein VP2 ( Yang et al., 2020 b) suggesting a deliberate mechanism where BTV drives the immune response away from an antiviral Th1 response.…”

“…2013 ; Yang et al., 2020 b; Rodríguez-Martín et al., 2021 ; Kopanke et al., 2020 ). IL-4 has been shown to be specifically induced by the BTV viral protein VP2 ( Yang et al., 2020 b) suggesting a deliberate mechanism where BTV drives the immune response away from an antiviral Th1 response. The Th2 response is critical for supporting a humoral immune response and IL-4 induction in BTV infections has been shown to increase throughout recovery ( Sánchez‐Cordón et al.…”