Fast type I interferon response protects astrocytes from flavivirus infection and virus-induced cytopathic effects

Lindqvist, Richard; Mundt, Filip; Gilthorpe, Jonathan D.; Wölfel, Silke; Gekara, Nelson O.; Kröger, Andrea; Överby, Anna K.

The type I IFN response could limit viral replication by different mechanisms: (i) restricting the spread of progeny viruses to neighboring cells, (ii) reducing overall viral replication, or (iii) both. To investigate this, WT and IFNAR −/− astrocytes and MEFs were infected by TBEV at a MOI of 0.1, stained by immunofluorescence, and the numbers of infected cells were quantified ( Fig. 2a shows a representative picture of infected wells). Even though the initial infections (24 hpi) in WT and IFNAR −/− astrocytes were comparable, the outcome of infection differed dramatically. Infection of WT astrocytes was low and never exceeded 20 %; however, infection of IFNAR −/− astrocytes was significantly higher at the late time points, reaching an average of 69 % at 72 hpi (Fig. 2b) . In MEFs, IFNAR expression failed to restrict TBEV spread, and no difference were observed between WT and IFNAR −/− cells (data not shown). These results suggest that IFNAR restricts the spread of TBEV in astrocytes.