Souphalone Luangsay1, Marion Gruffaz1, Nathalie Isorce1, Barbara Testoni1, Maud Michelet1, Suzanne Faure-Dupuy1, Sarah Maadadi1, Malika Ait-Goughoulte1, Romain Parent1, Michel Rivoire2, Hassan Javanbakht3, Julie Lucifora1, David Durantel4, Fabien Zoulim5. 1. INSERM U1052, Cancer Research Center of Lyon (CRCL), Lyon 69008, France; University of Lyon, UMR_S1052, UCBL, 69008 Lyon, France. 2. Centre Léon Bérard (CLB), Lyon 69008, France; INSERM U1032, 69003 Lyon, France. 3. Hoffmann-La Roche Ltd, Roche Pharmaceutical Research and Early Development, 4070 Basel, Switzerland. 4. INSERM U1052, Cancer Research Center of Lyon (CRCL), Lyon 69008, France; University of Lyon, UMR_S1052, UCBL, 69008 Lyon, France. Electronic address: david.durantel@inserm.fr. 5. INSERM U1052, Cancer Research Center of Lyon (CRCL), Lyon 69008, France; University of Lyon, UMR_S1052, UCBL, 69008 Lyon, France; Hospices Civils de Lyon (HCL), 69002 Lyon, France; Institut Universitaire de France (IUF), 75005 Paris, France. Electronic address: fabien.zoulim@inserm.fr.
Abstract
BACKGROUND & AIMS: The outcome of hepatitis B virus (HBV) infection may be influenced by early interactions between the virus and hepatocyte innate immune responses. To date, the study of such interactions during the very early step of infection has not been adequately investigated. METHODS: We used the HepaRG cell line, as well as primary human hepatocytes to analyze, within 24h of exposure to HBV, either delivered by a physiologic route or baculovirus vector (Bac-HBV), the early modulation of the expression of selected antiviral/pro-inflammatory cytokines and interferon stimulated genes. Experiments were also performed in the presence or absence of innate receptor agonists to investigate early HBV-induced blockade of innate responses. RESULTS: We show that hepatocytes themselves could detect HBV, and express innate genes when exposed to either HBV virions or Bac-HBV. Whereas Bac-HBV triggered a strong antiviral cytokine secretion followed by the clearance of replicative intermediates, a physiologic HBV exposure led to an abortive response. The early inhibition of innate response by HBV was mainly evidenced on Toll-like receptor 3 and RIG-I/MDA5 signaling pathways upon engagement with exogenous agonist, leading to a decreased expression of several pro-inflammatory and antiviral cytokine genes. Finally, we demonstrate that this early inhibition of dsRNA-mediated response is due to factor(s) present in the HBV inoculum, but not being HBsAg or HBeAg themselves, and does not require de novo viral protein synthesis and replication. CONCLUSIONS: Our data provide strong evidence that HBV viral particles themselves can readily inhibit host innate immune responses upon virion/cell interactions, and may explain, at least partially, the "stealthy" character of HBV.
BACKGROUND & AIMS: The outcome of hepatitis B virus (HBV) infection may be influenced by early interactions between the virus and hepatocyte innate immune responses. To date, the study of such interactions during the very early step of infection has not been adequately investigated. METHODS: We used the HepaRG cell line, as well as primary human hepatocytes to analyze, within 24h of exposure to HBV, either delivered by a physiologic route or baculovirus vector (Bac-HBV), the early modulation of the expression of selected antiviral/pro-inflammatory cytokines and interferon stimulated genes. Experiments were also performed in the presence or absence of innate receptor agonists to investigate early HBV-induced blockade of innate responses. RESULTS: We show that hepatocytes themselves could detect HBV, and express innate genes when exposed to either HBV virions or Bac-HBV. Whereas Bac-HBV triggered a strong antiviral cytokine secretion followed by the clearance of replicative intermediates, a physiologic HBV exposure led to an abortive response. The early inhibition of innate response by HBV was mainly evidenced on Toll-like receptor 3 and RIG-I/MDA5 signaling pathways upon engagement with exogenous agonist, leading to a decreased expression of several pro-inflammatory and antiviral cytokine genes. Finally, we demonstrate that this early inhibition of dsRNA-mediated response is due to factor(s) present in the HBV inoculum, but not being HBsAg or HBeAg themselves, and does not require de novo viral protein synthesis and replication. CONCLUSIONS: Our data provide strong evidence that HBV viral particles themselves can readily inhibit host innate immune responses upon virion/cell interactions, and may explain, at least partially, the "stealthy" character of HBV.