Human pDCs preferentially sense enveloped hepatitis A virions
Zongdi Feng, … , Christopher M. Walker, Stanley M. Lemon
Zongdi Feng, … , Christopher M. Walker, Stanley M. Lemon
Published November 21, 2014
Citation Information: J Clin Invest. 2015;125(1):169-176. https://doi.org/10.1172/JCI77527.
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Research Article Virology

Human pDCs preferentially sense enveloped hepatitis A virions

Abstract

Unlike other picornaviruses, hepatitis A virus (HAV) is cloaked in host membranes when released from cells, providing protection from neutralizing antibodies and facilitating spread in the liver. Acute HAV infection is typified by minimal type I IFN responses; therefore, we questioned whether plasmacytoid dendritic cells (pDCs), which produce IFN when activated, are capable of sensing enveloped virions (eHAV). Although concentrated nonenveloped virus failed to activate freshly isolated human pDCs, these cells produced substantial amounts of IFN-α via TLR7 signaling when cocultured with infected cells. pDCs required either close contact with infected cells or exposure to concentrated culture supernatants for IFN-α production. In isopycnic and rate-zonal gradients, pDC-activating material cosedimented with eHAV but not membrane-bound acetylcholinesterase, suggesting that eHAV, and not viral RNA exosomes, is responsible for IFN-α induction. pDC activation did not require virus replication and was associated with efficient eHAV uptake, which was facilitated by phosphatidylserine receptors on pDCs. In chimpanzees, pDCs were transiently recruited to the liver early in infection, during or shortly before maximal intrahepatic IFN-stimulated gene expression, but disappeared prior to inflammation onset. Our data reveal that, while membrane envelopment protects HAV against neutralizing antibody, it also facilitates an early but limited detection of HAV infection by pDCs.

Authors

Zongdi Feng, You Li, Kevin L. McKnight, Lucinda Hensley, Robert E. Lanford, Christopher M. Walker, Stanley M. Lemon

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Figure 3

Differential uptake of eHAV versus nonenveloped HAV by pDCs.

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Differential uptake of eHAV versus nonenveloped HAV by pDCs. (A) pDCs we...
(A) pDCs were exposed to equal quantities of gradient-purified eHAV or nonenveloped HAV, and cell-associated viral RNA and supernatant IFN-α levels were determined at intervals. Circles and squares represent cells from 2 individual donors, respectively. (B) pDCs were incubated with eHAV in the presence or absence of annexin V (2 or 10 μg/ml), and cell-associated viral RNA was determined at intervals by RT-qPCR. (C) IFN-α produced by pDCs exposed to concentrated supernatant fluids from mock- or HM175/p16-infected cell cultures in the presence or absence of annexin V (2 μg/ml). (D) IFN-α produced by pDCs exposed to gradient-purified eHAV following inactivation by UV light or cultured with eHAV in the presence of 100 μM HAV 3Cpro inhibitor (3C-inh) (EC90 = 62 μM, CC50 = 3 mM). Efficiency of UV inactivation and 3C inhibitor treatment. Huh-7.5 cells were infected with UV-inactivated eHAV or nontreated eHAV in the presence of 3C-inh, and cell-associated HAV RNA was measured by RT-qPCR and compared with that in cells infected with untreated HAV at 48 hours. (E) pDCs were transfected with HM175/18f genomic RNA in the presence and absence of IRS-661 or subgenomic HAV-luc RNA or a replication incompetent variant HAV-Luc-Δ3D. Supernatant IFN-α levels were measured by ELISA. Results represent the mean ± SEM (n = 2 or 3 cultures) obtained with pDCs from single donors.