Enterovirus E infects bovine peripheral blood mononuclear cells. Implications for pathogenesis?

Introduction: Enterovirus E (EV-E) is a common viral pathogen endemic in cattle worldwide. Little is known, however, about its potential interactions with bovine immune cells. Material and Methods: The EV-E-permissiveness of bovine peripheral blood mononuclear cells (PBMCs) was evaluated. The infectious titres of extracellular virus were measured and the intracellular viral RNA levels were determined by reverse transcription quantitative PCR after cell inoculation. The effects of EV-E on cell viability and proliferative response were investigated with a methyl thiazolyl tetrazolium bromide reduction assay, the percentages of main lymphocyte subsets and oxidative burst activity of blood phagocytes were determined with flow cytometry, and pro-inflammatory cytokine secretion was measured with an ELISA. Results: Enterovirus E productively infected bovine PBMCs. The highest infectious dose of EV-E decreased cell viability and T-cell proliferation. All of the tested doses of virus inhibited the proliferation of high responding to lipopolysaccharide B cells and stimulated the secretion of interleukin 1β, interleukin 6 and tumour necrosis factor α pro-inflammatory cytokines. Conclusion: Interactions of EV-E with bovine immune cells may indicate potential evasion mechanisms of the virus. There is also a risk that an infection with this virus can predispose the organism to secondary infections, especially bacterial ones.