Interplay between the cellular restriction factor PML and dengue virus

CYBELE GARCÍA; PETER HEMMERICH; FEDERICO GIOVANNONI

Hamburgo

Congreso; 6th European Congress of Virology; 2016

European Society for Virology

Intrinsic immunity is a form of innate immunity that provides a potent protection from viral infection. It is mediated by constitutively-expressed cellular proteins, known as restriction factors, that block viral replication immediately. Promyelocytic leukemia (PML) protein contributes to intrinsic immunity against many viruses. PML forms nuclear bodies (NB) that serve as a hub for an interaction network consisting of over 100 proteins. Many viral proteins disrupt PML NBs. This has led to the hypothesis that the disruption of the NB structure may be a viral strategy to evade the host antiviral response. We have previously reported the antiviral role of PML against dengue virus serotype 2 (DENV2). Here, we performed further studies to characterize the antiviral role of PML during in vitro replication of other DENV serotypes (DENV1-4) as well as the molecular mechanism behind this effect. Intracellular localization of PML NBs in A549 cells during DENV infection was analyzed by immunofluorescence. These studies showed that NB distribution was not altered during early infection (18 h), the NBs underwent a rearrangement. In particular, the number of PML NBs per nucleus was significantly lower in DENV infected cells compared to controls. To determine if the disruption of NB during DENV infection could be a consequence of the interaction between PML and a viral component, cells were transfected with vectors expressing C or NS5 DENV2 proteins. C and NS5 have been shown to localize to the nucleus and therefore were considered likely candidates for interaction with PML. Confocal images showed that expression of C did not alter the typical punctate pattern of PML NBs. However, expression of NS5 correlated with a diminished count of PML NBs per cell nucleus. Overall, we show for the first time a potentially functional interplay between PML NBs and DENV1-4. Moreover, our data suggest that NS5-mediated disassembly of PML NBs is an important mechanism in Dengue virus propagation. Future studies will unravel the molecular events underlying PML NB-DENV interaction.