Identification of Host Trafficking Genes Required for HIV-1 Virological Synapse Formation in Dendritic Cells

Abstract

Dendritic cells (DCs) are one of the earliest targets of HIV-1 infection acting as a “Trojan horse,” concealing the virus from the innate immune system and delivering it to T cells via virological synapses (VS). To explicate how the virus is trafficked through the cell to the VS and evades degradation, a high-throughput small interfering RNA screen targeting membrane trafficking proteins was performed in monocyte-derived DCs. We identified several proteins including BIN-1 and RAB7L1 that share common roles in transport from endosomal compartments. Depletion of target proteins resulted in an accumulation of virus in intracellular compartments and significantly reduced viral trans-infection via the VS. By targeting endocytic trafficking and retromer recycling to the plasma membrane, we were able to reduce the virus’s ability to accumulate at budding microdomains and the VS. Thus, we identify key genes involved in a pathway within DCs that is exploited by HIV-1 to traffic to the VS. IMPORTANCE The lentivirus human immunodeficiency virus (HIV) targets and destroys CD4+ T cells, leaving the host vulnerable to life-threatening opportunistic infections associated with AIDS. Dendritic cells (DCs) form a virological synapse (VS) with CD4+ T cells, enabling the efficient transfer of virus between the two cells. We have identified cellular factors that are critical in the induction of the VS. We show that ADP-ribosylation factor 1 (ARF1), bridging integrator 1 (BIN1), and Rab GTPases RAB7L1 and RAB8A are important regulators of HIV-1 trafficking to the VS and therefore the infection of CD4+ T cells. We found these cellular factors were essential for endosomal protein trafficking and formation of the VS and that depletion of target proteins prevented virus trafficking to the plasma membrane by retaining virus in intracellular vesicles. Identification of key regulators in HIV-1 trans-infection between DC and CD4+ T cells has the potential for the development of targeted therapy to reduce trans-infection of HIV-1 in vivo.

Viral cell-to-cell spread: Conventional and non-conventional ways

“…Similar to HTLV-1, in HIV-1-infected T cells (effector cells) Env and Gag are quickly recruited to the VS ( Do et al, 2014 ; Jolly et al, 2004 ). Polarization of the MTOC and associated organelles towards the VS is induced in HIV-infected lymphocytes and DCs to hijack components of the secretory pathway ( Bayliss et al, 2020 ; Jolly et al, 2011 ). In adjacent uninfected T CD4 + cells, an actin-dependent recruitment of CD4, CXCR4 and lymphocyte function-associated antigen 1 (LFA-1) was found to facilitate spread of Gag molecules between cells ( Jolly et al, 2004 ).…”

Targeting Endosomal Recycling Pathways by Bacterial and Viral Pathogens

“…These bacteria pathogens utilize different types of secretion systems and a plethora of effector proteins to create a unique vacuolar compartment known as pathogen vacuoles or inclusion, in which they can replicate. Similarly, some viruses, including human immunodeficiency virus (HIV) ( Groppelli et al, 2014 ; Bayliss et al, 2020 ), hepatitis C virus (HCV) ( Yin et al, 2016 ), human papillomavirus (HPV) ( Lipovsky et al, 2013 ; Ganti et al, 2016 ), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2; Cattin-Ortolá et al, 2020 ; Daniloski et al, 2020 ; Gordon et al, 2020 ), also interact with components of the endosomal recycling machinery during infection ( Table 1 ). In this review, we will discuss recent advances in understanding how pathogenic bacteria subvert essential endosomal recycling pathways in the host.…”

The importance of virion-incorporated cellular RNA-Binding Proteins in viral particle assembly and infectivity

“…This is a RAS-related subfamily fundamental for the regulation of vesicle formation, trafficking and docking at target membranes, and has been implicated in the infection cycles of many pathogens [ 108 ]. ARFs have been involved in the recruitment of HIV-1 RNPs to the plasma membrane and the release of HIV-1 particles [ 109 ], and ARF1 regulates HIV-1 trafficking to the virological synapse [ 110 ]. Additionally, ARF1 is necessary for HCV RNA replication and production of infectious particles [ 111 ].…”