Abortive and productive infection of CNS cell types following in vivo delivery of VSV

Viral infection is frequently assayed by ongoing expression of viral genes. These assays fail to identify cells that have been exposed to the virus but limit or inhibit viral replication. To address this limitation, we used a dual-labeling vesicular stomatitis virus (DL-VSV), which has a deletion of the viral glycoprotein gene, to allow evaluation of primary infection outcomes. This virus encodes Cre, which can stably mark any cell with even a minimal level of viral gene expression. Additionally, the virus encodes GFP, which distinguishes cells with higher levels of viral gene expression, typically due to genome replication. Stereotactic injections of DL-VSV into the murine brain showed that different cell types had very different responses to the virus. Almost all neurons hosted high levels of viral gene expression, while glial cells varied in their responses. Astrocytes (Sox9+) were predominantly productively infected, while oligodendrocytes (Sox10+) were largely abortively infected. Microglial cells (Iba1+) were primarily uninfected. Furthermore, we monitored the early innate immune response to viral infection and identified unique patterns of interferon (IFN) induction. Shortly after infection, microglia were the main producers of IFNb , whereas later, oligodendrocytes were the main producers. IFNb + cells were primarily abortively infected regardless of cell type. Last, we investigated whether IFN signaling had any impact on the outcome of primary infection and did not observe significant changes, suggesting that intrinsic factors are likely responsible for determining the outcome of primary infection.