DENGUE VIRUS NS5 PROTEIN TARGETS PML NUCLEAR BODIES INVOLVED IN INTRINSIC IMMUNITY

FEDERICO GIOVANNONI; CYBELE GARCÍA; PETER HEMMERICH

Madison

Congreso; 36th Annual Meeting - American Society for Virology; 2017

American Society for Virology

Intrinsic immunity is a form of innate immunity that is mediatedby constitutively expressed cellular proteins which can block viralreplication immediately.Promyelocytic leukemia (PML) protein contributes to intrinsic immunityagainst many viruses. PML forms structures called nuclear bodies(PML-NBs) which are frequently targeted by viruses to overcome PMLmediatedimmunity.Previously, we described the antiviral role of PML against dengue virusserotype 2 (DENV-2). Here, we performed further studies to characterizethe role of PML in the in-vitro replication of other DENV serotypes(DENV1-4) as well as the molecular mechanism underlying this effect.Confocal microscopy revealed that the number of PML-NBs wassignificantly lower in DENV1-4-infected A549 cells. Even thoughflaviviruses, such as DENV, replicate in the cytoplasm DENV proteinsC and NS5 can localize to the nucleus. This nuclear localization is stillconsidered enigmatic in DENV biology.To determine if the disruption of PML-NBs could be a consequence ofan interaction between PML and C or NS5, cells were transfected withvectors encoding for C or NS5. Confocal images showed that quantitativeexpression of NS5, but not C, was sufficient to reduce the number of PMLNBs.Immunoprecipitation studies confirmed complex formation betweenNS5 and PML. Finally we show that overexpression of PML isoforms IIIand IV, but not the other nuclear PML isoforms induce an accumulation ofNS5 at PML-NBs.Overall, we show for the first time a phenotypic as well as functionalinterplay between PML and DENV1-4. DENV-2 NS5 is found in acomplex with PML and its expression alone is sufficient to disrupt PMLNBs.We conclude that NS5 nuclear localization may be important forinhibiting PML-mediated immune responses.