Coronaviruses that cause severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) are speculated to have originated in bats. The mechanisms by which these viruses are maintained in individuals or populations of reservoir bats remain an enigma. Mathematical models have predicted long-term persistent infection with low levels of periodic shedding as a likely route for virus maintenance and spillover from bats. In this study, we tested the hypothesis that bat cells and MERS coronavirus (CoV) can co-exist in vitro . To test our hypothesis, we established a long-term coronavirus infection model of bat cells that are persistently infected with MERS-CoV. We infected cells from Eptesicus fuscus with MERS-CoV and maintained them in culture for at least 126 days. We characterized the persistently infected cells by detecting virus particles, protein and transcripts. Basal levels of type I interferon in the long-term infected bat cells were higher, relative to uninfected cells, and disrupting the interferon response in persistently infected bat cells increased virus replication. By sequencing the whole genome of MERS-CoV from persistently infected bat cells, we identified that bat cells repeatedly selected for viral variants that contained mutations in the viral open reading frame 5 (ORF5) protein. Furthermore, bat cells that were persistently infected with ΔORF5 MERS-CoV were resistant to superinfection by wildtype virus, likely due to reduced levels of the virus receptor, dipeptidyl peptidase 4 (DPP4) and higher basal levels of interferon in these cells. In summary, our study provides evidence for a model of coronavirus persistence in bats, along with the establishment of a unique persistently infected cell culture model to study MERS-CoV-bat interactions.
【저자키워드】 Evolution, Microbiology, Molecular biology, Biological techniques, Cell Biology, 【초록키워드】 Coronavirus infection, coronavirus, Mutation, Sequencing, Infection, interferon, in vitro, MERS, virus, MERS-CoV, type I interferon, Population, DPP4, Dipeptidyl peptidase 4, Protein, Culture, mathematical model, cells, persistence, CoV, bat, virus replication, virus receptor, viral variant, bats, interactions, mechanism, Evidence, Hypothesis, Middle East, MERS coronavirus, acute respiratory syndrome, Frame, These cells, individual, syndrome, transcripts, virus particles, basal, wildtype, infected cell, whole genome, uninfected cells, Cell, ORF5, selected, tested, predicted, virus, reduced, characterized, provide, unique, the interferon, Eptesicus, disrupting, infected cell culture, 【제목키워드】 Infection, Selection, viral variant, Middle East, respiratory syndrome coronavirus, Cell,