interleukin-8 and Bovine-Virus-Diarrhea-Mucosal-Disease

Viruses have developed cellular strategies to ensure progeny survival. One of the most interesting is immune camouflage, where the virus triggers a controlled-intensity immune response that prevents total destruction of the infected cell, thus "winning time" for the virus. This study explored the regulatory contexts of the bovine A20 gene during bovine viral diarrhea virus (BVDV)-1 infection, using IL-8 as an immune-response sentinel molecule. Assessments were conducted through RT-qPCR, Western blotting, gene silencing/overexpression, luciferase assays, and the use of pharmacological inhibitors, among other approaches. The results demonstrated that a) BVDV-1 increased A20 levels in Madin-Darby bovine kidney cells, b) increased A20 led to decreased IL-8 expression, and c) the virus affected the NF-κB signaling pathway. Collectively, these data identify bovine A20 as a strong regulator of immune marker expression. In conclusion, this is the first report on BVDV-1 modulating bovine IL-8 activation through the NF-κB/A20 pathway.

Topics: Animals; Bovine Virus Diarrhea-Mucosal Disease; Cattle; Cell Line; Diarrhea Virus 1, Bovine Viral; Epithelial Cells; Gene Expression Regulation; Immunity; Immunomodulation; Interleukin-8; Kidney; NF-kappa B; RNA, Small Interfering; Signal Transduction; Tumor Necrosis Factor alpha-Induced Protein 3

The immediate early response 3 (IER3) is a key regulatory factor in the immune response, particularly as related to homeostasis immunomodulation via the nuclear factor kappa B (NF-κB) signaling pathway. The IER3 gene has been identified in mammals and, more recently, in other higher vertebrates. Nevertheless, relatively little is known about this regulator in bovines. Therefore, this study explored, characterized, and compared the genetic context of bovine IER3 to homologous genes in the human, mouse, and canine chromosomes. In silico analysis identified several regions of interest preserved in phylogenetically distant species. Similar analyses were also conducted for interleukin-8, a cytokine in which several putative cis elements were identified for the inducible transcription factor NF-κB. Subsequent challenge assays against the bovine viral diarrhea virus-1 revealed NF-κB signaling pathway activation just 15min post-infection, a process blocked by the BAY-117085 inhibitor. Similarly, infection strongly increased IER3 expression. Interestingly, IER3 down-regulated interleukin-8 expression, as confirmed by IER3 gene inhibition using small interfering RNA, RT-qPCR, and luciferase assays. In conclusion, this is the first report to present data indicating that bovine IER3 is a strong regulator of immune-marker expression, specifically modulating bovine interleukin-8 activation through the NF-κB/IER3 pathway in response to the bovine viral diarrhea virus.

Topics: Animals; Apoptosis Regulatory Proteins; Bovine Virus Diarrhea-Mucosal Disease; Cattle; Diarrhea Virus 1, Bovine Viral; Dogs; Interleukin-8; Madin Darby Canine Kidney Cells; NF-kappa B; Signal Transduction

Alveolar macrophages (AM) were recovered by bronchoalveolar lavage from a group of eight calves at various times before and after inoculation with a cytopathic respiratory isolate of bovine viral diarrhoea virus (BVDV). A second group of four calves were given tissue culture medium as a control inoculum. Macrophages were also recovered from two additional, uninoculated calves, and were exposed to BVDV in vitro. Tests were carried out on the recovered macrophages to determine the effects of the virus on several functional properties. Immunofluorescence did not indicate the AM as being readily susceptible to this isolate of BVDV, although infection did occur. Fc receptor (FcR) and complement receptor (C3R) expression, phagocytosis and microbicidal activity and the production of neutrophil chemotactic factors were all significantly reduced in macrophages recovered from BVDV infected calves, compared with pre-inoculation control levels, whereas the control inoculated calves displayed significant increases in some of the functions. With macrophages exposed to the virus in vitro however, only FcR and C3R expression and phagocytic activity were significantly reduced. The results demonstrate that BVDV can reduce local immune defences in the lung, following infection by the respiratory route, and in conjunction with the other immunosuppressive properties of BVDV would favour a pre-disposing role for the virus in the pathogenesis of respiratory disease in calves.

Topics: Animals; Antibodies, Viral; Bovine Virus Diarrhea-Mucosal Disease; Bronchoalveolar Lavage Fluid; Candida; Cattle; Cell Line; Cells, Cultured; Cytotoxicity, Immunologic; Diarrhea Viruses, Bovine Viral; Fluorescent Antibody Technique; Interleukin-8; Lung; Macrophages, Alveolar; Phagocytosis; Receptors, Complement; Receptors, Fc