Bovine Viral Diarrhea Virus Type 2 Impairs Macrophage Responsiveness to Toll-Like Receptor Ligation with the Exception of Toll-Like Receptor 7

• Published in: PloS one Vol. 11; no. 7; p. e0159491
• Main Authors: Schaut, Robert G, Ridpath, Julia F, Sacco, Randy E
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 15-07-2016; Public Library of Science (PLoS)
• Subjects: Animal diseases; Animals; Biology and Life Sciences; Biotypes; Blood & organ donations; Bovine viral diarrhea virus; Bovine Virus Diarrhea-Mucosal Disease - genetics; Bovine Virus Diarrhea-Mucosal Disease - immunology; Bovine Virus Diarrhea-Mucosal Disease - pathology; Cattle; Causes of; Cell culture; Cells, Cultured; Comparative analysis; Cytokines; Cytokines - genetics; Cytokines - immunology; Cytopathogenic Effect, Viral; Development and progression; Diarrhea; Diarrhea Virus 2, Bovine Viral - immunology; Diarrhea Virus 2, Bovine Viral - pathogenicity; Diarrhea Virus 2, Bovine Viral - physiology; Epithelial cells; Flaviviridae; Gene expression; Gene Expression Regulation; Genetic aspects; Hepatitis; Immune system; Immunity; Immunology; Immunosuppression; Infections; Inflammation; Innate immunity; Interferon; Interleukin 6; Interleukin-6 - genetics; Interleukin-6 - immunology; Macrophages; Macrophages - immunology; Macrophages - pathology; Macrophages - virology; Medicine and Health Sciences; Monocytes; mRNA; Physiological aspects; Proteins; Receptors; Research and Analysis Methods; RNA, Messenger - genetics; Signaling; TLR2 protein; TLR3 protein; TLR7 protein; Toll-Like Receptor 7 - immunology; Toll-like receptors; Toll-Like Receptors - immunology; Viral infections; Virulence; Virulence (Microbiology); Viruses; United States; United States > US; Iowa
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0159491

Bovine viral diarrhea virus (BVDV) is a member of the Flaviviridae family. BVDV isolates are classified into two biotypes based on the development of cytopathic (cp) or non-cytopathic (ncp) effects in epithelial cell culture. BVDV isolates are further separated into species, BVDV1 and 2, based on genetic differences. Symptoms of BVDV infection range from subclinical to severe, depending on strain virulence, and may involve multiple organ systems and induction of a generalized immunosuppression. During BVDV-induced immune suppression, macrophages, critical to innate immunity, may have altered pathogen recognition receptor (PRR) signaling, including signaling through toll-like receptors (TLRs). Comparison of BVDV 2 strains with different biotypes and virulence levels is valuable to determining if there are differences in host macrophage cellular responses between viral phenotypes. The current study demonstrates that cytopathic (cp), noncytopathic (ncp), high (hv) or low virulence (lv) BVDV2 infection of bovine monocyte-derived macrophages (MDMΦ) result in differential expression of pro-inflammatory cytokines compared to uninfected MDMΦ. A hallmark of cp BVDV2 infection is IL-6 production. In response to TLR2 or 4 ligation, as might be observed during secondary bacterial infection, cytokine secretion was markedly decreased in BVDV2-infected MDMΦ, compared to non-infected MDMΦ. Macrophages were hyporesponsive to viral TLR3 or TLR8 ligation. However, TLR7 stimulation of BVDV2-infected MDMΦ induced cytokine secretion, unlike results observed for other TLRs. Together, these data suggest that BVDV2 infection modulated mRNA responses and induced a suppression of proinflammatory cytokine protein responses to TLR ligation in MDMΦ with the exception of TLR7 ligation. It is likely that there are distinct differences in TLR pathways modulated following BVDV2 infection, which have implications for macrophage responses to secondary infections.