Dendritic Cells Preferentially Transfer CXCR4-Using Human Immunodeficiency Virus Type 1 Variants to CD4⁺T Lymphocytes intrans

Abstract

Human immunodeficiency virus type 1 (HIV-1) preferentially utilizes the CCR5 coreceptor for target cell entry in the acute phase of infection, while later in disease progression the virus switches to the CXCR4 coreceptor in approximately 50% of patients. In response to HIV-1 the adaptive immune response is triggered, and antibody (Ab) production is elicited to block HIV-1 entry. We recently determined that dendritic cells (DCs) can efficiently capture Ab-neutralized HIV-1, restore infectivity, and transmit infectious virus to target cells. Here, we tested the effect of Abs on trans transmission of CCR5 or CXCR4 HIV-1 variants. We observed that transmission of HIV-1 by immature as well as mature DCs was significantly higher for CXCR4-than CCR5-tropic viral strains. Additionally, neutralizing Abs directed against either the gp41 or gp120 region of the envelope such as 2F5, 4E10, and V3-directed Abs inhibited transmission of CCR5-tropic HIV-1, whereas Ab-treated CXCR4-tropic virus demonstrated unaltered or increased transmission. To further study the effects of coreceptor usage we tested molecularly cloned HIV-1 variants with modifications in the envelope that were based on longitudinal gp120 V1 and V3 variable loop sequences from a patient progressing to AIDS. We observed that DCs preferentially facilitated infection of CD4 ؉ T lymphocytes of viral strains with an envelope phenotype found late in disease. Taken together, our results illustrate that DCs transmit CXCR4-tropic HIV-1 much more efficiently than CCR5 strains; we hypothesize that this discrimination could contribute to the in vivo coreceptor switch after seroconversion and could be responsible for the increase in viral load.

Reactivation of Neutralized HIV-1 by Dendritic Cells Is Dependent on the Epitope Bound by the Antibody

“…The mechanism for why an MPER bNAb like 2F5 cannot resist DC-mediated HIV-1 transmission was shown for a single R5X4 virus. However, we showed previously that the 2F5 bNAb could not block DC-mediated HIV-1 transmission of viruses using CCR5, CXCR4, or both coreceptors (27). Combined, these results suggest that the MPER Ab-dissociation mechanism is independent of coreceptor usage.…”

“…Mature monocyte-derived DCs (mMDDCs) were obtained on day 6 after stimulating iMDDCs on day 5 with 20 mg polyinosinic-polycytidylic acid/ml (Sigma-Aldrich, St. Louis, MO). The phenotypes of both types of DCs were confirmed by flow cytometry (27).…”

“…5D). The increase in HIV-1 colocalization with MHC class II on mMDDCs probably resulted from recruitment of MHC class II to the plasma membrane upon DC maturation (27). Coinciding with a high level of HIV-1 at the plasma membrane of mMDDCs, we observed a reduction in virus colocalized with a number of intracellular markers (EEA1 ∼3%, CD63 ∼5%, and HLA-DM ∼4%).…”

“…Molecular cloned R5X4 GFP-fluorescent HIV-1 (26,27) was generated by cotransfecting HEK 293T cells with GFP-VPR and full-length proviral 299.10DgV3 HIV-1 vector (28) in a 1:1 ratio. The supernatant, containing HIV-1 GFP , was collected 3 d after transfection and concentrated using Amicon Ultra filters (100,000 m.w.…”

“…We demonstrated previously that neutralized HIV-1 captured by DCs could regain infectivity upon viral transmission in trans to CD4 + T lymphocytes (26,27). Most Abs, such as 2F5, 4E10, or V3, could not prevent this DC-mediated viral transmission; in contrast, the b12 Ab efficiently blocked viral transfer.…”