Transcriptional analysis of immune-related genes in dendritic cells from hepatitis B surface antigen (HBsAg)-positive transgenic mice and regulation of Fc gamma receptor IIB by HBsAg-anti-HBs complex

Virus-Host Protein Interaction Network of the Hepatitis E Virus ORF2-4 by Mammalian Two-Hybrid Assays

Throughout their life cycle, viruses interact with cellular host factors, thereby influencing propagation, host range, cell tropism and pathogenesis. The hepatitis E virus (HEV) is an underestimated RNA virus in which knowledge of the virus-host interaction network to date is limited. Here, two related high-throughput mammalian two-hybrid approaches (MAPPIT and KISS) were used to screen for HEV-interacting host proteins. Promising hits were examined on protein function, involved pathway(s), and their relation to other viruses. We identified 37 ORF2 hits, 187 for ORF3 and 91 for ORF4. Several hits had functions in the life cycle of distinct viruses. We focused on SHARPIN and RNF5 as candidate hits for ORF3, as they are involved in the RLR-MAVS pathway and interferon (IFN) induction during viral infections. Knocking out (KO) SHARPIN and RNF5 resulted in a different IFN response upon ORF3 transfection, compared to wild-type cells. Moreover, infection was increased in SHARPIN KO cells and decreased in RNF5 KO cells. In conclusion, MAPPIT and KISS are valuable tools to study virus-host interactions, providing insights into the poorly understood HEV life cycle. We further provide evidence for two identified hits as new host factors in the HEV life cycle.

FTH1 expression is affected by promoter polymorphism and not DNA methylation in response to DHV-1 challenge in duck

Ferritin heavy polypeptide 1 (FTH1) plays a pivotal role in response to viral infections. FTH1 expression is modulated by various pathogens, but the regulatory mechanisms are unknown. We firstly construct duck hepatitis virus 1 (DHV-1) infection model, including morbid ducklings, non-morbid ducklings and control ducklings. Then the mRNA expression of duck FTH1 (duFTH1) was measured mRNA expression of duck FTH1 (duFTH1) in the liver and spleen after duck hepatitis virus 1 (DHV-1) infection using quantitative polymerase chain reaction (qPCR) and found that duFTH1 mRNA was down-regulated significantly in morbid ducklings (liver, P < 0.01; spleen, P < 0.05) compared with the control ducklings. We also found that duFTH1 expression was significantly higher in the spleen (P < 0.01) and liver (P < 0.05) of non-morbid ducklings than in morbid ducklings. Moreover, DNA methylation of the duFTH1 promoter was examined by bisulfite sequencing (BSP) and we found that the duFTH1 promoter was hypomethylated, the relative methylation was only 5.9% and 2.0% in the morbid ducklings and non-morbid ducklings, respectively. The promoter contained a -55 C/T mutation in 75% of non-morbid ducklings, and this polymorphism affected promoter activity. Further analysis suggested that this mutation altered the binding site of the transcription factor NRF1. Binding of NRF1 to the FTH1 promoter was confirmed by electrophoretic mobility shift assay (EMSA) analysis. Thus, our findings revealed the NRF1 was a negative regulator, and lossed of binding of NRF1 to duFTH1 promoter due to -55C/T mutation enhances duFTH1 expression in non-morbid ducks, which provided molecular insights into the effect of duFTH1 expression via promoter polymorphisms, but not DNA methylation, in response to DHV-1 challenge.

Intrahepatic innate immune response pathways are downregulated in untreated chronic hepatitis B

BACKGROUND & AIMS

Hepatitis B virus (HBV) persistence and the pathobiology of chronic HBV (CHB) infections result from the interplay between viral replication and host immune responses. We aimed to comprehensively analyse the expression of intrahepatic host genes as well as serum and liver HBV markers in a large cohort of untreated CHB patients.

METHODS

One-hundred and five CHB patients untreated at the time of liver biopsy (34 HBeAg[+] and 71 HBeAg[-]) were analysed for the intrahepatic expression profile of 67 genes belonging to multiple innate immunity pathways. Results were correlated to serological (quantification of HBsAg [qHBsAg] and HBV DNA) and intrahepatic viral markers (total HBV DNA, pre-genomic RNA and covalently closed circular HBV DNA).

RESULTS

Intrahepatic gene expression profiling revealed a strong downregulation of antiviral effectors, interferon stimulated genes, Toll-like and pathogen recognition receptor pathways in CHB patients as compared to non-infected controls, which was not directly correlated to HBV replication. A subset of genes [CXCL10, GBP1, IFITM1, IFNB1, IL10, IL6, ISG15, TLR3, SOCS1, SOCS3] was more repressed in HBeAg(-) respect to HBeAg(+) patients (median of serum HBV DNA 7.9×10³vs. 7.9×10⁷IU/ml, respectively). Notably, HBeAg(-) patients with lower qHBsAg (<5×10³IU/ml) showed a relief of repression of genes belonging to multiple pathways.

CONCLUSIONS

Our results show a strong impairment of innate immune responses in the liver of CHB patients. The association of low levels of qHBsAg with gene repression, if confirmed, might prove useful for the identification of patients who would most benefit from immune-modulators and/or HBsAg targeting agents as strategies to restore immune responsiveness.

LAY SUMMARY

Chronic hepatitis B virus (HBV) infections represent a major public health problem worldwide. Over 200 million people are chronically infected and at risk of developing chronic hepatitis, liver cirrhosis and cancer. Our work aimed to understand the molecular consequences of chronic hepatitis B in the infected liver. It was conducted in a large cohort of untreated chronically infected HBV patients and analysed the expression of immunity and liver disease-related genes in the liver, with respect to markers of viral replication and persistence. Our results indicate that chronic HBV infection has a suppressive effect on immune responses, which was more pronounced with high levels of hepatitis B virus surface antigen (HBsAg). These data provide novel insight into the mechanisms of HBV persistence in the liver and suggest that approaches aimed at reducing HBsAg levels, may restore immune responsiveness against the virus.

Therapeutic vaccination for chronic hepatitis B

A therapeutic vaccine is meant to activate the patient's immune system to fight and finally control or ideally eliminate an already established infectious pathogen. Whereas the success of prophylactic vaccination is based on rapid antibody-mediated neutralization of an invading pathogen, control and elimination of persistent viruses such as hepatitis, herpes or papilloma viruses requires multi-specific and polyfunctional effector T cell responses. These are ideally directed against continuously expressed viral antigens to keep the pathogen in check. Activation of a humoral immune response in order to lower viral antigen load and to limit virus spread, however, confers an additional benefit. Therapeutic vaccines are under development for a number of chronic infections and require an intelligent vaccine design. Hepatitis B virus (HBV) infection may serve as a prime example since a spontaneous, immune-mediated recovery of chronic hepatitis B and an elimination of the virus is possible even if it is observed only in very rare cases. In this review, we summarize the current knowledge and potential improvements of therapeutic vaccines for chronic hepatitis B.

Design, expression, and characterization of a novel dendritic cell-targeted proteins

In vivo approaches to inducing an effective immune response focus on targeted antigen (Ag) delivery to dendritic cells (DCs). In this study, we developed a new method of targeting plasmid DNA and/or the antigen (Ag)-antibody (Ab) complex to DCs via the DC receptor DEC-205, also known as cluster of differentiation CD205. We cloned and expressed a recombinant protein composed of mouse DEC-205-specific single-chain fragment variable region (mDEC-205-scFv), the streptococcal protein G (SPG) IgG-binding domain and cationic peptide (CP), which named mDEC205-scFv-SPG-CP (msSC). In vitro, the recombinant protein msSC can specifically bind to DCs through the section of mDEC-205-scFv, and bound the Ag-Ab complex via SPG as well as plasmid DNA through electrostatic bonding with CP in vitro. In addition, msSC functioned in a manner similar to anti-DEC-205 monoclonal Ab and bound to mouse bone marrow-derived DCs. It was demonstrated in vivo that msSC can target plasmid DNA to DCs, resulting in efficient uptake and expression. Moreover, msSC can form a complex with pGL3-CMV and transport it to draining lymph nodes when injected in vivo. These results indicate that msSC can be used as a carrier protein for vaccine delivery to DCs via formation of plasmid DNA-Ag-Ab ternary complexes.

Molecular cloning and expression analysis of ferritin, heavy polypeptide 1 gene from duck (Anas platyrhynchos)

H-ferritin is a core subunit of the iron storage protein ferritin, and is related to the pathogenesis of malignant diseases. A differential expressed sequence tag of the ferritin, heavy polypeptide 1 gene (FTH1) was obtained from our previously constructed suppression subtractive cDNA library from 3-day-old ducklings challenged with duck hepatitis virus type I (DHV-1). The expression and function of FTH1 in immune defense against infection remains largely unknown in ducks. In this study, the full-length duFTH1 cDNA was obtained using reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends. It consisted of 153 basepairs (bp) 5'untranslated region (UTR), 183 bp 3'UTR, and 546 bp open reading frame that encodes a single protein of 181 amino acid residues. duFTH1 shares high similarity with FTH1 genes from other vertebrates. The amino acid sequence possesses the conserved domain of typical ferritin H subunits, including seven metal ligands in the ferroxidase center, one iron binding region signature, and a potential bio-mineralization residue (Thy(29)). Moreover, in agreement with a previously reported ferritin H subunit, we identified an iron response element in the 5'UTR. RT-PCR analyses revealed duFTH1 mRNA is widely expressed in various tissues. Real-time quantitative polymerase chain reaction analyses suggested that duFTH1 mRNA is significantly up-regulated in the liver after DHV-1 injection or polyriboinosinic polyribocytidylic acid (polyI:C) treatment, reaching a peak 4 h post-infection, and dropping progressively and returning to normal after 24 h. Our findings suggest that duFTH1 functions as an iron chelating protein subunit in duck and contributes to the innate immune responses against viral infections.