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Hepatitis delta virus (HDV) is a defective satellite virus that uses hepatitis B virus (HBV) envelope proteins to form its virions and infect hepatocytes via the HBV receptors. Concomitant HDV/HBV infection continues to be a major health problem, with at least 25 million people chronically infected worldwide. N(6)-methyladenine (m6A) modification of cellular and viral RNAs is the most prevalent internal modification that occurs cotranscriptionally, and this modification regulates various biological processes. We have previously described a wider range of functional roles of m6A methylation of HBV RNAs, including its imminent regulatory role in the encapsidation of pregenomic RNA. In this study, we present evidence that m6A methylation also plays an important role in the HDV life cycle. Using the methylated RNA immunoprecipitation (MeRIP) assay, we identified that the intracellular HDV genome and antigenome are m6A methylated in HDV- and HBV-coinfected primary human hepatocytes and HepG2 cell expressing sodium taurocholate cotransporting polypeptide (NTCP), while the extracellular HDV genome is not m6A methylated. We observed that HDV genome and delta antigen levels are significantly decreased in the absence of METTL3/14, while the extracellular HDV genome levels are increased by depletion of METTL3/14. Importantly, YTHDF1, an m6A reader protein, interacts with the m6A-methylated HDV genome and inhibits the interaction between the HDV genome and antigens. Thus, m6A of the HDV genome negatively regulates virion production by inhibiting the interaction of the HDV genome with delta antigens through the recruitment of YTHDF1. This is the first study that provides insight into the functional roles of m6A in the HDV life cycle. IMPORTANCE The functional roles of N(6)-methyladenine (m6A) modifications in the HBV life cycle have been recently highlighted. Here, we investigated the functional role of m6A modification in the HDV life cycle. HDV is a subviral agent of HBV, as it uses HBV envelope proteins to form its virions. We found that m6A methylation also occurs in the intracellular HDV genome and antigenome but not in the extracellular HDV genome. The m6A modification of the HDV genome recruits m6A reader protein (YTHDF1) onto the viral genome. The association of YTHDF1 with the HDV genome abrogates the interaction of delta antigens with the HDV genome and inhibits virion assembly. This study describes the unique effects of m6A on regulation of the HDV life cycle.

Magnetoacoustic waves generated in piezoelectric and ferromagnetic coupled nanocomposite films through magnetically driven surface acoustic waves present great promise of loss-less data transmission. In this work, ferromagnetic metals of Ni, Co and Co

Self-assembled oxide–metallic alloy nanopillars as hybrid plasmonic metamaterials (e.g., ZnO–AgxAu1−x) in a thin film form have been grown using a pulsed laser deposition method. The hybrid films were demonstrated to be highly tunable via systematic tuning of the oxygen background pressure during deposition. The pressure effects on morphology and optical properties have been investigated and found to be critical to the overall properties of the hybrid films. Specifically, low background pressure results in the vertically aligned nanocomposite (VAN) form while the high-pressure results in more lateral growth of the nanoalloys. Strong surface plasmon resonance was observed in the UV-vis region and a hyperbolic dielectric function was achieved due to the anisotropic morphology. The oxide–nanoalloy hybrid material grown in this work presents a highly effective approach for tuning the binary nanoalloy morphology and properties through systematic parametric changes, important for their potential applications in integrated photonics and plasmonics such as sensors, energy harvesting devices, and beyond.

Hepatitis B virus (HBV) encodes a regulatory protein, termed HBx, that has been intensely studied in the past and shown to play a key role(s) in viral transcription and replication. In addition, a huge body of work exists in the literature related to signal transduction and possible mechanism(s) leading to hepatocarcinogenesis associated with infection. We have previously reported that HBV transcripts are modified by N6-methyladenosine (m6A) at the single consensus DRACH motif at nucleotides (nt) 1905 to 1909 in the epsilon structural element, and this m6A modification affects the HBV life cycle. In this study, we present evidence that additional variants of m6A (DRACH) motifs located within nt 1606 to 1809 correspond to the coding region of HBx mRNA and 3′ untranslated region (UTR) of other viral mRNAs. Using the mutants of additional m6A sites in nt 1606 to 1809 and a depletion strategy of m6A methyltransferases (METTL3/14) and reader proteins (YTHDFs), we show that m6A modification at nt 1616, located in the HBx coding region, regulates HBx protein expression. The HBx RNA and protein expression levels were notably increased by the silencing of m6A reader YTHDF2 and methyltransferases as well as the mutation of m6A sites in the HBx coding region. However, other viral protein expression levels were not affected by the m6A modification at nt 1616. Thus, m6A modifications in the HBx open reading frame (ORF) downregulate HBx protein expression, commonly seen during HBV transfections, transgenic mice, and natural infections of human hepatocytes. These studies identify the functional role of m6A modification in the subtle regulation of HBx protein expression consistent with its possible role in establishing chronic hepatitis. IMPORTANCE N6-methyladenosien (m6A) modifications recently have been implicated in the HBV life cycle. Previously, we observed that m6A modification occurs in the adenosine at nt 1907 of the HBV genome, and this modification regulates the viral life cycle. Here, we identified an additional m6A site located in nt 1616 of the HBV genome. This modification negatively affects HBx RNA and protein expression. In the absence of m6A methyltransferases (METTL3/14) and reader protein (YTHDF2), the HBx RNA and protein expression were increased. Using HBV mutants that lack m6A in the HBx coding region, we present the unique positional effects of m(6)A in the regulation of HBx protein expression.

Significance HBV infections are the leading cause of chronic hepatitis and carry the risk of liver cirrhosis and cancer. The HBV life cycle is perpetuated by an RNA intermediate termed pregenomic RNA (pgRNA), which is encapsidated by the viral core protein. The pgRNA packaging process is an essential step in viral replication. Here, we investigated the role of N6-methyladenosine (m 6 A) modification in the recognition of pgRNA by the core protein during encapsidation. m 6 A modification of 5′ epsilon structural motifs serves as the recognition signal for the core protein interaction, as evidenced by the failure of 5′ epsilon m 6 A mutant to encapsidate pgRNA. This study identifies the structural role of m 6 A modification in pgRNA encapsidation and provides an avenue in RNA–protein complex interactions.

N(6)-Methyladenosine (m(6)A), the methylation of the adenosine base at the nitrogen 6 position, is the most common epitranscriptomic modification of mRNA that affects a wide variety of biological functions. We have previously reported that hepatitis B viral RNAs are m(6)A-modified, displaying a dual functional role in the viral life cycle. Here, we show that cellular m(6)A machinery regulates host innate immunity against hepatitis B and C viral infections by inducing m(6)A modification of viral transcripts. The depletion of the m(6)A writer enzymes (METTL3 and METTL14) leads to an increase in viral RNA recognition by retinoic acid–inducible gene I (RIG-I), thereby stimulating type I interferon production. This is reversed in cells in which m(6)A METTL3 and METTL14 are overexpressed. The m(6)A modification of viral RNAs renders RIG-I signaling less effective, whereas single nucleotide mutation of m(6)A consensus motif of viral RNAs enhances RIG-I sensing activity. Importantly, m(6)A reader proteins (YTHDF2 and YTHDF3) inhibit RIG-I–transduced signaling activated by viral RNAs by occupying m(6)A-modified RNAs and inhibiting RIG-I recognition. Collectively, our results provide new insights into the mechanism of immune evasion via m(6)A modification of viral RNAs.

This paper demonstrates a monolithic surface acoustic wave amplifier fabricated by state-of-the-art heterogenous integration of a III-V InGaAs-based epitaxial material stack and LiNbO3. We compare amplification of Raleigh-SAW and leaky-SAW modes on a on Y-cut, X-propagating delay line amplifier. Due to the superior properties of the materials employed, we observe a net terminal gain of 3dB for an LSAW overtone mode This platform enables further advances in active and non-reciprocal piezoelectric acoustic devices.

Hyperbolic metamaterials are a class of materials exhibiting anisotropic dielectric function owing to the morphology of the nanostructures. In these structures, one direction behaves as a metal, and the orthogonal direction behaves as a dielectric material. Applications include subdiffraction imaging and hyperlenses. However, key limiting factors include energy losses of noble metals and challenging fabrication methods. In this work, self-assembled plasmonic metamaterials consisting of anisotropic nanoalloy pillars embedded into the ZnO matrix are developed using a seed-layer approach. Alloys of Au

YTHDC1 and fragile X mental retardation protein (FMRP) bind N6-methyladenosine (m6A)-modified RNAs and facilitate their transport to the cytoplasm. Here, we investigated the role of these proteins in hepatitis B virus (HBV) gene expression and life cycle. We have previously reported that HBV transcripts are m6A methylated, and this modification regulates the viral life cycle. HBV is particularly interesting, as its DNA genome upon transcription gives rise to a pregenomic RNA (pgRNA), which serves as a template for reverse transcription to produce the relaxed circular DNA that transforms into a covalently closed circular DNA (cccDNA). While m6A modification negatively affects RNA stability and translation of viral transcripts, our current results revealed the possibility that it positively affects pgRNA encapsidation in the cytoplasm. Thus, it plays a differential dual role in the virus life cycle. YTHDC1 as well as FMRP recognize m6A-methylated HBV transcripts and facilitate their transport to the cytoplasm. In cells depleted with YTHDC1 or FMRP, viral transcripts accumulate in the nucleus to affect the viral life cycle. Most importantly, the core-associated DNA and subsequent cccDNA syntheses are dramatically affected in FMRP- or YTHDC1-silenced cells. This study highlights the functional relevance of YTHDC1 and FMRP in the HBV life cycle with the potential to arrest liver disease pathogenesis. IMPORTANCE YTHDC1 and FMRP have been recently implicated in the nuclear export of m6A modified mRNAs. Here, we show that FMRP and YTHDC1 proteins bind with m6A-modified HBV transcripts and facilitate their nuclear export. In the absence of FMRP and YTHDC1, HBV transcripts accumulate in the nucleus to reduce reverse transcription in HBV core particles and subsequently the cccDNA synthesis. Our study shows how m6A binding proteins can regulate the HBV life cycle by facilitating the nuclear export of m6A-modified HBV RNA.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a respiratory pathogen leading to serious multi-organ damage. However, little is known about SARS-CoV-2-induced cellular alterations for understanding robust virus propagation yet. Here we report that SARS-CoV-2 aberrantly elevates mitochondrial bioenergetics and activates epidermal growth factor receptor (EGFR)-mediated cell survival signal cascade for sustaining persistence of SARS-CoV-2. We found that SARS-CoV-2 causes increase in mitochondrial transmembrane potential by SARS-CoV-2 RNA-nucleocapsid cluster, thereby abnormally promoting mitochondrial biogenesis and oxidative phosphorylation (OXPHOS) process followed by abundant ATP production. SARS-CoV-2 also activated EGFR signal cascade and subsequent mitochondrial EGFR accumulation which contributes to the maintenance of abnormal OXPHOS and viral propagation. Therapeutic options for the treatment of COVID-19 are still inadequate. The FDA-approved EGFR inhibitors caused a remarkable reduction in SARS-CoV-2 propagation. Among EGFR inhibitors, vandetanib showing the highest anti-SARS-CoV-2 efficacy exhibited the potent antiviral activity against various SARS-CoV-2 variants including B.1.1.7 (UK variant) and B.1.351 (SA variant) lineages in both in vitro cell culture and in vivo animal experiments using wild-type aged mouse susceptible to SARS-CoV-2 infection, suggesting that EGFR is an attractive host target for combatting COVID-19. Overall, our results suggest that SARS-CoV-2 induces aberrant mitochondrial dynamics and bioenergetics, which significantly contributes to robust SARS-CoV-2 propagation.

Epitaxial lithium niobate (LNO) thin films are an attractive material for devices across a broad range of fields, including optics, acoustics, and electronics. These applications demand high‐quality thin films without in‐plane growth domains to reduce the optical/acoustical losses and optimize efficiency. Twin‐free single‐domain‐like growth has been achieved previously, but it requires specific growth conditions that might be hard to replicate. In this work, a versatile nanocomposite‐seeded approach is demonstrated as an effective approach to grow single‐domain epitaxial lithium niobate thin films. Films are grown through a pulsed laser deposition method and growth conditions are optimized to achieve high‐quality epitaxial film. A comprehensive microstructure characterization is performed and optical properties are measured. A piezoelectric acoustic resonator device is developed to demonstrate the future potential of the nanocomposite‐seeded approach for high‐quality LNO growth for radio frequency (RF) applications.

This paper describes the theoretical and experimental investigation of interdigitated transducers capable of producing focused acoustical beams in thin film piezoelectric materials. A mathematical formalism describing focused acoustical beams, lamb beams, is presented and related to their optical counterparts in two- and three-dimensions. A novel Fourier domain transducer design methodology is developed and utilized to produce near diffraction limited focused beams within a thin film AlN membrane. The properties of the acoustic beam formed by the transducer were studied by means of Doppler vibrometry implemented with a scanning confocal balanced homodyne interferometer. The Fourier domain modal analysis confirmed that 83% of the acoustical power was delivered to the targeted focused beam which was constituted from the lowest order symmetric mode, while 1% was delivered unintentionally to the beam formed from the anti-symmetric mode, and the remaining power was isotropically scattered. The transmission properties of the acoustic beams as they interact with devices with wavelength scale features were also studied, demonstrating minimal insertion loss for devices in which a subwavelength and pinhole apertures were included. [2018-0059]

YTHDC1 and fragile X mental retardation protein (FMRP) bind N(6)-methyladenosine (m(6)A)-modified RNAs and facilitate their transport to the cytoplasm. Here, we investigated the role of these proteins in hepatitis B virus (HBV) gene expression and life cycle. We have previously reported that HBV transcripts are m(6)A methylated, and this modification regulates the viral life cycle. HBV is particularly interesting, as its DNA genome upon transcription gives rise to a pregenomic RNA (pgRNA), which serves as a template for reverse transcription to produce the relaxed circular DNA that transforms into a covalently closed circular DNA (cccDNA). While m(6)A modification negatively affects RNA stability and translation of viral transcripts, our current results revealed the possibility that it positively affects pgRNA encapsidation in the cytoplasm. Thus, it plays a differential dual role in the virus life cycle. YTHDC1 as well as FMRP recognize m(6)A-methylated HBV transcripts and facilitate their transport to the cytoplasm. In cells depleted with YTHDC1 or FMRP, viral transcripts accumulate in the nucleus to affect the viral life cycle. Most importantly, the core-associated DNA and subsequent cccDNA syntheses are dramatically affected in FMRP- or YTHDC1-silenced cells. This study highlights the functional relevance of YTHDC1 and FMRP in the HBV life cycle with the potential to arrest liver disease pathogenesis. IMPORTANCE YTHDC1 and FMRP have been recently implicated in the nuclear export of m(6)A modified mRNAs. Here, we show that FMRP and YTHDC1 proteins bind with m(6)A-modified HBV transcripts and facilitate their nuclear export. In the absence of FMRP and YTHDC1, HBV transcripts accumulate in the nucleus to reduce reverse transcription in HBV core particles and subsequently the cccDNA synthesis. Our study shows how m(6)A binding proteins can regulate the HBV life cycle by facilitating the nuclear export of m(6)A-modified HBV RNA.

N6-methyladenosine (m6A) is the most prevalent modification of mammalian cellular RNAs. m6A methylation is linked to epigenetic regulation of several aspects of gene expression, including RNA stability, splicing, nuclear export, RNA folding, and translational activity. m6A modification is reversibly catalyzed by methyltransferases (m6A writers) and demethylases (m6A erasers), and the dynamics of m6A-modified RNA are regulated by m6A-binding proteins (m6A readers). Recently, several studies have shown that m6A methylation sites have been identified in hepatitis B virus (HBV) transcripts and the hepatitis C virus (HCV) RNA genome. Here, we review the role of m6A modification in HBV/HCV replication and its contribution to liver disease pathogenesis. A better understanding of the functions of m6A methylation in the life cycles of HBV and HCV is required to establish the role of these modifications in liver diseases associated with these viral infections., Hepatitis: Role of RNA modification Further investigations into the role of RNA modifications during hepatitis B and C infections could improve understanding of the hepatitis-associated liver disease. The most common RNA modification found in mammalian cells is N6-methyladenosine (m6A), which is linked to multiple cellular processes including gene regulation. This modification has also been identified in viral RNA, prompting Geon-Woo Kim and Aleem Siddiqui at the University of California, San Diego, USA, to review understanding of m6A modification during hepatitis virus infections. Depending on which part of the viral RNA is m6A-methylated, m6A modification induces complex changes in the viral life cycle. Infection with either hepatitis B or C virus also affects m6A modifications in host cellular RNA, influencing gene expression and inhibiting immunity. This may influence the development of liver disease and cancer during chronic hepatitis infection.

Hepatitis C virus (HCV) infections are associated with the risk of progression to fibrosis, cirrhosis, and hepatocellular carcinoma. The HCV RNA genome is translated by an internal ribosome entry site (IRES)-dependent mechanism. The structure and function of the HCV IRES have been investigated by both biological and biophysical criteria. Recently, the role of N6-methyladenosine (m(6)A) in cellular RNA and viral transcripts has been intensely investigated. The HCV RNA genome is m(6)A-methylated, and this modification regulates the viral life cycle. In this study, we investigated the role of m(6)A modification of the HCV genome in the IRES-dependent translation function by mutating m(6)A consensus motifs (DRACH) within the IRES element in stem–loop III and IV regions and studied their effect on translation initiation. There are several DRACH motifs within the IRES element. Of these, the DRACH motif at nucleotide (nt) 329-333, located about 7 nt upstream of initiator AUG (iAUG) codon, regulates IRES-mediated translation initiation. Mutational analysis showed that m(6)A methylation of the adenosine at nt 331 is essential for the IRES-dependent translation. m(6)A reader protein YTHDC2, containing the RNA helicase domain, recognizes m(6)A-methylated adenosine at nt 331 and, in concert with the cellular La antigen, supports HCV IRES-dependent translation. The RNA helicase dead YTHDC2 (E332Q) mutant failed to stimulate HCV translation initiation. This report highlights the functional roles of m(6)A modification and YTHDC2 in the HCV IRES-dependent translation initiation, thus offering alternative therapeutic avenues to interfere with the infectious process.

Background and aims Epitranscriptomic modification of RNA has emerged as the most prevalent form of regulation of gene expression that affects development, differentiation, metabolism, viral infections, and most notably cancer. We have previously shown that hepatitis B virus (HBV) transcripts are modified by N6 methyladenosine (m6 A) addition. HBV also affects m6 A modification of several host RNAs, including phosphatase and tensin homolog (PTEN), a well-known tumor suppressor. PTEN plays a critical role in antiviral innate immunity and the development of hepatocellular carcinoma (HCC). Reports have shown that PTEN controlled interferon regulatory factor 3 (IRF-3) nuclear localization by negative phosphorylation of IRF-3 at Ser97, and PTEN reduced carcinogenesis by inhibiting the phosphatidylinositol-3-kinase (PI3K)/AKT pathway. Approach and results Here, we show that HBV significantly increases the m6 A modification of PTEN RNA, which contributes to its instability with a corresponding decrease in PTEN protein levels. This is reversed in cells in which the expression of m6 A methyltransferases is silenced. PTEN expression directly increases activated IRF-3 nuclear import and subsequent interferon synthesis. In the absence of PTEN, IRF-3 dephosphorylation at the Ser97 site is decreased and interferon synthesis is crippled. In chronic HBV patient biopsy samples, m6 A-modified PTEN mRNA levels were uniformly up-regulated with a concomitant decrease of PTEN mRNA levels. HBV gene expression also activated the PI3K/AKT pathway by regulating PTEN mRNA stability in HCC cell lines. Conclusions The m6 A epitranscriptomic regulation of PTEN by HBV affects innate immunity by inhibiting IRF-3 nuclear import and the development of HCC by activating the PI3K/AKT pathway. Our studies collectively provide new insights into the mechanisms of HBV-directed immune evasion and HBV-associated hepatocarcinogenesis through m6 A modification of the host PTEN mRNAs.

Contour mode resonators in suspended AlN films experience performance limitations from anchors and bussing. To mitigate this, we show how confocal acoustical resonators designed with tailored electrode shapes increase quality factor by concentrating the mode energy toward the resonator center, focusing the cavity mode away from anchors, while also maintaining coupling coefficient even with extremely tight focusing. We present a theoretical treatment for electrode design and present an experimental analysis comparing straight fingered vs focused cavity, showing both a Q increase and constant coupling coefficient while the radius of curvature is increased from loose focusing to the diffraction limit.

Chronic hepatitis B virus (HBV) infections are one of the leading causes of cirrhosis and hepatocellular carcinoma. N6-methyladenosine (m(6)A) modification of cellular and viral RNAs is the most prevalent internal modification that occurs cotranscriptionally. Previously, we reported the dual functional role of m(6)A modification of HBV transcripts in the viral life cycle. Here, we show that viral HBV X (HBx) protein is responsible for the m(6)A modifications of viral transcripts. HBV genomes defective in HBx failed to induce m(6)A modifications of HBV RNAs during infection/transfection, while ectopic expression of HBx restores m(6)A modifications of the viral RNAs but not the mutant HBx carrying the nuclear export signal. Using chromatin immunoprecipitation assays, we provide evidence that HBx and m(6)A methyltransferase complexes are localized on the HBV minichromosome to achieve cotranscriptional m(6)A modification of viral RNAs. HBx interacts with METTL3 and 14 to carry out methylation activity and also modestly stimulates their nuclear import. This role of HBx in mediating m(6)A modification also extends to host phosphatase and tensin homolog (PTEN) mRNA. This study provides insight into how a viral protein recruits RNA methylation machinery to m(6)A-modify RNAs.

Electric fields in a surface acoustic wave in a piezoelectric substrate can pattern charge in an adjacent graphene film via the acousto-electric effect and thus reconfigure the optical transmission in an unpatterned graphene metasurface.

Epitaxial single-domain LiNbO3 thin-films are realized using a novel nanocomposite seeding method. Full microstructure characterization and optical property measurement is conducted as a first step to demonstrate viability of this material for integrated photonics applications.

N6-methyladenosine (m6A) is the most prevalent and internal modification of eukaryotic mRNA. Multiple m6A methylation sites have been identified in the viral RNA genome and transcripts of DNA viruses in recent years. m6A modification is involved in all the phases of RNA metabolism, including RNA stability, splicing, nuclear exporting, RNA folding, translational modulation, and RNA degradation. Three protein groups, methyltransferases (m6A-writers), demethylases (m6A-erasers), and m6A-binding proteins (m6A-readers) regulate this dynamic reversible process. Here, we have reviewed the role of m6A modification dictating viral replication, morphogenesis, life cycle, and its contribution to disease progression. A better understanding of the m6A methylation process during viral pathogenesis is required to reveal novel approaches to combat the virus-associated diseases.