The maturation of dendritic cells results in postintegration inhibition ofHIV-1 replication

Maturation of dendritic cells (DC) is known to result in decreased capacity to produce HIV due to postentry block of its replicative cycle. In this st udy, we compared the early phases of this cycle in immature DC (iDC) and ma ture DC (mDC) generated from monocytes cultured with GM-CSF and IL-4, trime ric CD40 ligand (DCCD40LT), monocyte-conditioned medium (DCMCM) being added or not from day 5, Culture day 8 cells exposed to X4 HIV-1(LAI) or RS HIV- 1(Ba-L),were analyzed by semiquantitative R-U5 PCR, which detects total HIV DNA, CXC chemokine receptor 4(low) (CXCR4(low)) CCR5(+) iDC harbored simil ar viral DNA amounts when exposed to either strain. HIV-1(LAI) entered more efficiently into DCCD40LT or DCMCM with up-regulated CXCR4, CCR5(low) DCCD 40LT still allowed entry of HIV-1(Ba-L), whereas CCRS- DCMCM displayed redu ced permissivity to this virus. Comparing amounts of late (long terminal re peat (LTR)-gag PCR) and total (R-U5 PCR) viral DNA products shelved that HI V-1(Ba-L) reverse transcription was more efficient than that of HIV-1(LAI), but was not affected by DC maturation. Southern blot detection of linear, circular, and integrated HIV DNA showed that maturation affected neither HI V-1 nuclear import nor integration. When assessing virus transcription by e xposing LDC to pNL6-3.GFP or pNL4-3.Luc viruses pseudotyped with the G prot ein of vesicular stomatitis virus(VSV-G), followed by culture with or witho ut CD40LT or MCM, GFP and luciferase activities decreased by 60-75% in mDC vs iDC, Thus, reduced HIV replication in mDC is primarily due to a postinte gration block occurring mainly at the transcriptional level, We could not r elate this block to altered expression and nuclear localization of NF-kappa B proteins and SP1 and SP3 transcription factors.