Reconstitution of interferon regulatory factor 7 expression restores interferon beta induction in Huh7 cells.

Abundance of essential components of double-stranded RNA (dsRNA) recognition and the subsequent interferon (IFN) response vary widely between primary human hepatocytes (PHHs) and commonly used cell culture models based on derivatives of Huh7 cells, supporting replication of all hepatitis viruses. We used RNA sequencing to compare the innate immune response in hepatoma cells with primary cells and non-neoplastic immortalized hepatocytes (PH5CH). Stimulation with the dsRNA analog poly(I:C) in Huh7 and Huh7.

RBM39 shapes innate immunity by controlling the expression of key factors of the interferon response.

Background And Aims: The contribution of innate immunity to clearance of viral infections of the liver, in particular sensing via Toll-like receptor 3 (TLR3), is incompletely understood. We aimed to identify the factors contributing to the TLR3 response in hepatocytes via CRISPR/Cas9 screening.

Methods: A genome-wide CRISPR/Cas9 screen on the TLR3 pathway was performed in two liver-derived cell lines, followed by siRNA knockdown validation.

Redefining the immune landscape of hepatitis A virus infection.

Despite the development of effective vaccines against hepatitis A virus (HAV) infection, outbreaks of acute hepatitis A still occur globally, such that HAV remains a major cause of acute viral hepatitis. Most patients with acute hepatitis A recover spontaneously; however, some adult cases result in acute liver failure due to immune-mediated liver damage. Previous studies suggested that HAV evades the innate immune response through strong counteractive mechanisms, and that HAV-specific CD8 T cells contribute to liver damage in patients with acute hepatitis A.

Limited impact of hepatitis A virus 3C protease-mediated cleavage on the functions of NEMO in human hepatocytes.

NF-κB essential modulator (NEMO) is critically involved in the induction of interferons (IFNs) and pro-inflammatory cytokines. Hepatitis A virus (HAV) 3C protease was recently identified to cleave NEMO in non-hepatic cells. This study aimed at understanding efficiency and function of HAV 3C-mediated NEMO cleavage in hepatocytes.

Phosphatidylinositol 4-Kinase III Alpha Governs Cytoskeletal Organization for Invasiveness of Liver Cancer Cells.

Background & Aims: High expression of phosphatidylinositol 4-kinase III alpha (PI4KIIIα) correlates with poor survival rates in patients with hepatocellular carcinoma. In addition, hepatitis C virus (HCV) infections activate PI4KIIIα and contribute to hepatocellular carcinoma progression. We aimed at mechanistically understanding the impact of PI4KIIIα on the progression of liver cancer and the potential contribution of HCV in this process.

Recruitment of both the ESCRT and autophagic machineries to ejecting Mycobacterium marinum.

Cytosolic Mycobacterium marinum are ejected from host cells such as macrophages or the amoeba Dictyostelium discoideum in a non-lytic fashion. As described previously, the autophagic machinery is recruited to ejecting bacteria and supports host cell integrity during egress. Here, we show that the ESCRT machinery is also recruited to ejecting bacteria, partially dependent on an intact autophagic pathway.

Comparison of HAV and HCV infections in vivo and in vitro reveals distinct patterns of innate immune evasion and activation.

Background & Aims: Hepatitis A virus (HAV) infections are considered not to trigger innate immunity in vivo, in contrast to hepatitis C virus (HCV). This lack of induction has been imputed to strong interference by HAV proteases 3CD and 3ABC. We aimed to elucidate the mechanisms of immune activation and counteraction by HAV and HCV in vivo and in vitro.

Biochemical and structural characterization of hepatitis A virus 2C reveals an unusual ribonuclease activity on single-stranded RNA.

The HAV nonstructural protein 2C is essential for virus replication; however, its precise function remains elusive. Although HAV 2C shares 24-27% sequence identity with other 2Cs, key motifs are conserved. Here, we demonstrate that HAV 2C is an ATPase but lacking helicase activity.

A Hepatitis C virus genotype 1b post-transplant isolate with high replication efficiency in cell culture and its adaptation to infectious virus production in vitro and in vivo.

Hepatitis C virus (HCV) is highly diverse and grouped into eight genotypes (gts). Infectious cell culture models are limited to a few subtypes and isolates, hampering the development of prophylactic vaccines. A consensus gt1b genome (termed GLT1) was generated from an HCV infected liver-transplanted patient.

Secretion of Hepatitis C Virus Replication Intermediates Reduces Activation of Toll-Like Receptor 3 in Hepatocytes.

Background & Aims: Hepatitis C virus (HCV) infections most often result in chronic outcomes, although the virus constantly produces replication intermediates, in particular double-stranded RNA (dsRNA), representing potent inducers of innate immunity. We aimed to characterize the fate of HCV dsRNA in hepatocyte cultures to identify mechanisms contributing to viral persistence in presence of an active innate immune response.

Methods: We analyzed hepatocyte-based culture models for HCV for induction of innate immunity, secretion of virus positive- or negative-strand RNA, and viral replication using different quantification methods and microscopy techniques.