Characterization of Human Immunodeficiency Virus Type 1 Replication in Immature and Mature Dendritic Cells Reveals Dissociablecis- andtrans-Infection

Dendritic cells (DCs) transmit human immunodeficiency virus type 1 (HIV-1) to CD4+ T cells through thetrans - andcis -infection pathways; however, little is known about the relative efficiencies of these pathways and whether they are interdependent. Here we comparecis - andtrans -infections of HIV-1 mediated by immature DCs (iDCs) and mature DCs (mDCs), using replication-competent and single-cycle HIV-1. Monocyte-derived iDCs were differentiated into various types of mDCs by lipopolysaccharide (LPS), tumor necrosis factor alpha (TNF-α), and CD40 ligand (CD40L). iDCs and CD40L-induced mDCs were susceptible to HIV-1 infection and mediated efficient viral transmission to CD4+ T cells. Although HIV-1cis -infection was partially restricted in TNF-α-induced mDCs and profoundly blocked in LPS-induced mDCs, these cells efficiently promoted HIV-1trans -infection of CD4+ T cells. The postentry restriction of HIV-1 infection in LPS-induced mDCs was identified at the levels of reverse transcription and postintegration, using real-time PCR quantification of viral DNA and integration. Furthermore, nucleofection of DCs with HIV-1 proviral DNA confirmed that impaired gene expression of LPS-induced mDCs was responsible for the postentry restriction of HIV-1 infection. Our results suggest that various DC subsets in vivo may differentially contribute to HIV-1 dissemination via dissociablecis - andtrans -infections.