Project description:Influenza B virus (IBV) is an acute respiratory pathogen that induces phenotypic alterations to the lung epithelium, such as the denudation of the respiratory cilium, during and after IBV infection. It has been assumed that these epithelial changes are non-adaptive, and simply the result of cellular death following lytic virus infection. However, previous reports have shown that not all infected cells are killed after viral infection; some cells can completely clear viral RNA and protein and persist in the host long-term. In this study, we utilized a novel recombinant virus in combination with a Cre recombinase-responsive transgenic mouse model to demonstrate that IBV infection leads to the formation of a population of survivor ciliated cells in the proximal airways of infected mice. We then performed transcriptional profiling on infected and surviving ciliated cell populations to determine how surviving viral infection affected these cells. To specifically profile ciliated cells, we digested mouse lungs and sorted cells based on their expression of CD24 with tdTomato as a marker of infection. We sorted cell populations from the lungs of animals mock infected with PBS (Mock), during active infection (2 DPI), and matched ciliated cell populations at 14 days post-infection that had either experienced direct viral infection (14 DPI Survivor Cell) or those that had never been infected (14 DPI). The resulting data indicate that after surviving infection and clearing the virus, survivor ciliated cells undergo significant transcriptional reprogramming.
Project description:Influenza B virus (IBV) is an acute respiratory pathogen that induces phenotypic alterations to the lung epithelium, such as the denudation of the respiratory cilium, during and after IBV infection. It has been assumed that these epithelial changes are non-adaptive, and simply the result of cellular death following lytic virus infection. However, previous reports have shown that not all infected cells are killed after viral infection; some cells can completely clear viral RNA and protein and persist in the host long-term. In this study, we utilized a novel recombinant virus in combination with a Cre recombinase-responsive transgenic mouse model to demonstrate that IBV infection leads to the formation of a population of survivor ciliated cells in the proximal airways of infected mice. To ensure that we were studying ciliated cells with markers that were maintained during viral infection in vivo, we performed single-cell transcriptional profiling on infected and surviving ciliated cell populations. We digested mouse lungs and sorted cells using tdTomato as a marker of infection. We sorted cell populations from the lungs of animals mock infected with PBS (Mock) and during active infection (2 DPI). The resulting data revealed that the marker CD24 is consistently expressed on ciliated cells before and during viral infection.
Project description:Influenza B virus (IBV) is an acute, respiratory RNA virus that has been assumed to induce the eventual death of all infected cells. We and others have shown however, that infection with apparently cytopathic viruses does not necessarily lead to cell death; some cells can intrinsically clear the virus and persist in the host long-term. To determine if any cells can survive direct IBV infection, we here generate a recombinant IBV capable of activating a host-cell reporter to permanently label all infected cells. Using this system, we demonstrate that IBV infection leads to the formation of a survivor cell population in the proximal airways that are ciliated-like, but transcriptionally and phenotypically distinct from both actively infected and bystander ciliated cells. We also show that survivor cells are critical to maintain respiratory barrier function. These results highlight a host response pathway that preserves the epithelium to limit the severity of IBV disease.
