Exosomes from Hepatitis C Infected Patients Transmit HCV Infection and Contain Replication Competent Viral RNA in Complex with Ago2-miR122-HSP90

Abstract

Antibodies targeting receptor-mediated entry of HCV into hepatocytes confer limited therapeutic benefits. Evidence suggests that exosomes can transfer genetic materials between cells; however, their role in HCV infection remains obscure. Here, we show that exosomes isolated from sera of chronic HCV infected patients or supernatants of J6/JFH1-HCV-infected Huh7.5 cells contained HCV RNA. These exosomes could mediate viral receptor-independent transmission of HCV to hepatocytes. Negative sense HCV RNA, indicative of replication competent viral RNA, was present in exosomes of all HCV infected treatment non-responders and some treatment-naïve individuals. Remarkably, HCV RNA was associated with Ago2, HSP90 and miR-122 in exosomes isolated from HCV-infected individuals or HCV-infected Huh7.5 cell supernatants. Exosome-loading with a miR-122 inhibitor, or inhibition of HSP90, vacuolar H⁺-ATPases, and proton pumps, significantly suppressed exosome-mediated HCV transmission to naïve cells. Our findings provide mechanistic evidence for HCV transmission by blood-derived exosomes and highlight potential therapeutic strategies. Since its first isolation and identification in 1989, Hepatitis C virus (HCV), has caused significant disease burden to humans worldwide. So far, there is no vaccine against HCV, and neutralizing antibody therapies to block receptor–mediated transmission of HCV to liver cells have so far achieved limited therapeutic benefits. This indicates that HCV can transmit infection via receptor-independent mechanisms. Evidence suggests that small host extracellular vesicles (exosomes) can mediate receptor-independent transfer of genetic material between cells, though their role in HCV transmission remains uncertain. Here, we found that the HCV virus can utilize host exosomes to transmit infection to naïve liver cells, even in the presence of potent blocking anti-HCV receptor antibody treatments. Additionally, we identified alternative treatment strategies that can block host exosomes from transmitting HCV infection. Our study provides novel insights to an alternative mechanism of HCV transmission that can compromise anti-HCV immune therapies and proposes potential therapeutic approaches to block exosome-mediated transmission of HCV infection.