Dengue virus (DENV) is a rapidly re-emerging flavivirus that causes dengue fever 
(DF), dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS), diseases 
for which there are no available therapies or vaccines.  The DENV-2 
positive-strand RNA genome contains 5' and 3' untranslated regions (UTRs) that 
have been shown to form secondary structures required for virus replication and 
interaction with host cell proteins.  In order to comprehensively identify host 
cell factors that bind the DENV-2 UTRs, we performed RNA chromatography, using 
the DENV-2 5' and 3' UTRs as "bait", combined with quantitative mass 
spectrometry.  We identified several proteins, including DDX6, G3BP1, G3BP2, 
Caprin1, and USP10, implicated in P body (PB) and stress granule (SG) function, 
and not previously known to bind DENV RNAs.  Indirect immunofluorescence 
microscopy showed these proteins to colocalize with the DENV replication 
complex.  Moreover, DDX6 knockdown resulted in reduced amounts of infectious 
particles and viral RNA in tissue culture supernatants following DENV infection. 
DDX6 interacted with DENV RNA in vivo during infection and in vitro this 
interaction was mediated by the DB1 and DB2 structures in the 3' UTR, possibly 
by formation of a pseudoknot structure.  Additional experiments demonstrate 
that, in contrast to DDX6, the SG proteins G3BP1, G3BP2, Caprin1 and USP10 bind 
to the variable region (VR) in the 3' UTR.  These results suggest that the 
DENV-2 3' UTR is a site for assembly of PB and SG proteins and, for DDX6, 
assembly on the 3' UTR is required for DENV replication.