Hepatitis C Virus Nonstructural Protein 5A Interacts with Immunomodulatory Kinase IKKε to Negatively Regulate Innate Antiviral Immunity.

Hepatitis C virus (HCV) infection can lead to chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. HCV employs diverse strategies to evade host antiviral innate immune responses to mediate a persistent infection. In the present study, we show that nonstructural protein 5A (NS5A) interacts with an NF-κB inhibitor immunomodulatory kinase, IKKε, and subsequently downregulats beta interferon (IFN-ß) promoter activity. We further demonstrate that NS5A inhibits DDX3-mediated IKKε and interferon regulatory factor 3 (IRF3) phosphorylation. We also note that hyperphosphorylation of NS5A mediats protein interplay between NS5A and IKKε, thereby contributing to NS5A-mediated modulation of IFN-ß signaling. Lastly, NS5A inhibits IKKε-dependent p65 phosphorylation and NF-κB activation. Based on these findings, we propose NS5A as a novel regulator of IFN signaling events, specifically by inhibiting IKKε downstream signaling cascades through its interaction with IKKε. Taken together, these data suggest an additional mechanistic means by which HCV modulates host antiviral innate immune responses to promote persistent viral infection.

Enhanced disease progression due to persistent HPV-16/58 infections in Korean women: a systematic review and the Korea HPV cohort study.

BACKGROUND: Persistent human papillomavirus (HPV) infection is a key factor for the development and progression of cervical cancer. We sought to identify the type-specific HPV prevalence by cervical cytology and assess disease progression risk based on high-risk persistent HPV infection in South Korea. METHODS: To investigate the HPV prevalence by Pap results, we searched seven literature databases without any language or date restrictions until July 17, 2019. To estimate the risk of disease progression by HPV type, we used the Korea HPV Cohort study data. The search included the terms "HPV" and "Genotype" and "Korea." Studies on Korean women, type-specific HPV distribution by cytological findings, and detailed methodological description of the detection assay were included. We assessed the risk of disease progression according to the high-risk HPV type related to the nonavalent vaccine and associated persistent infections in 686 HPV-positive women with atypical squamous cells of uncertain significance or low-grade squamous intraepithelial lesions from the Korea HPV Cohort Study. Type-specific HPV prevalence was the proportion of women positive for a specific HPV genotype among all HPV-positive women tested for that genotype in the systematic review. RESULTS: We included 23 studies in our review. HPV-16 was the most prevalent, followed by HPV-58, -53, -70, -18, and -68. In women with high-grade squamous intraepithelial lesions, including cancer, HPV-16, -18, and -58 were the most prevalent. In the longitudinal cohort study, the adjusted hazard ratio of disease progression from atypical squamous cells of uncertain significance to high-grade squamous intraepithelial lesions was significantly higher among those with persistent HPV-58 (increase in risk: 3.54-5.84) and HPV-16 (2.64-5.04) infections. CONCLUSIONS: While HPV-16 was the most prevalent, persistent infections of HPV-16/58 increased the risk of disease progression to high-grade squamous intraepithelial lesions. Therefore, persistent infections of HPV-16 and -58 are critical risk factors for cervical disease progression in Korea. Our results suggest that equal attention should be paid to HPV-58 and -16 infections and provide important evidence to assist in planning the National Immunization Program in Korea.

Antiviral activity of digoxin and ouabain against SARS-CoV-2 infection and its implication for COVID-19.

The current coronavirus (COVID-19) pandemic is exacerbated by the absence of effective therapeutic agents. Notably, patients with COVID-19 and comorbidities such as hypertension and cardiac diseases have a higher mortality rate. An efficient strategy in response to this issue is repurposing drugs with antiviral activity for therapeutic effect. Digoxin (DIG) and ouabain (OUA) are FDA drugs for heart diseases that have antiviral activity against several coronaviruses. Thus, we aimed to assess antiviral activity of DIG and OUA against SARS-CoV-2 infection. The half-maximal inhibitory concentrations (IC50) of DIG and OUA were determined at a nanomolar concentration. Progeny virus titers of single-dose treatment of DIG, OUA and remdesivir were approximately 103-, 104- and 103-fold lower (> 99% inhibition), respectively, than that of non-treated control or chloroquine at 48 h post-infection (hpi). Furthermore, therapeutic treatment with DIG and OUA inhibited over 99% of SARS-CoV-2 replication, leading to viral inhibition at the post entry stage of the viral life cycle. Collectively, these results suggest that DIG and OUA may be an alternative treatment for COVID-19, with potential additional therapeutic effects for patients with cardiovascular disease.

Antiviral activity of interferon-stimulated gene 20, as a putative repressor binding to hepatitis B virus enhancer II and core promoter.

BACKGROUND AND AIM: Interferon-stimulated gene 20 (ISG20) is an interferon-inducible exonuclease that inhibits the replication of several RNA viruses. In patients with chronic hepatitis B, ISG20 expression is related to the interferon-α treatment response. However, the molecular mechanism of ISG20-mediated anti-hepatitis B virus (HBV) activity is unclear. METHODS: We have investigated the effect of ISG20 on antiviral activity to address that. The life cycle of HBV was analyzed by the ectopic expression of ISG20 in HepG2 and HepG2-NTCP cells. Finally, to provide physiological relevance of our study, the expression of ISG20 from chronic hepatitis B patients was examined. RESULTS: Interferon-stimulated gene 20 was mainly induced by interferon-ß and dramatically inhibited HBV replication. In addition, ISG20 decreased HBV gene expression and transcription. Although ISG20 inhibited HBV replication by reducing viral enhancer activity, the expression of transcription factors that bind the HBV enhancer was not affected. Particularly, ISG20 suppressed HBV enhancer activity by binding to the enhancer II and core promoter (EnhII/Cp) region. CONCLUSION: Our findings suggest that ISG20 exerts the anti-HBV activity by acting as a putative repressor binding to the HBV EnhII/Cp region.

Identification of a quadruple mutation that confers tenofovir resistance in chronic hepatitis B patients.

BACKGROUND & AIMS: Tenofovir disoproxil fumarate (TDF) is one the most potent nucleot(s)ide analogues for treating chronic hepatitis B virus (HBV) infection. Phenotypic resistance caused by genotypic resistance to TDF has not been reported. This study aimed to characterize HBV mutations that confer tenofovir resistance. METHODS: Two patients with viral breakthrough during treatment with TDF-containing regimens were prospectively enrolled. The gene encoding HBV reverse transcriptase was sequenced. Eleven HBV clones harboring a series of mutations in the reverse transcriptase gene were constructed by site-directed mutagenesis. Drug susceptibility of each clone was determined by Southern blot analysis and real-time PCR. The relative frequency of mutants was evaluated by ultra-deep sequencing and clonal analysis. RESULTS: Five mutations (rtS106C [C], rtH126Y [Y], rtD134E [E], rtM204I/V, and rtL269I [I]) were commonly found in viral isolates from 2 patients. The novel mutations C, Y, and E were associated with drug resistance. In assays for drug susceptibility, the IC50 value for wild-type HBV was 3.8 ±â€¯0.6 µM, whereas the IC50 values for CYE and CYEI mutants were 14.1 ±â€¯1.8 and 58.1 ±â€¯0.9 µM, respectively. The IC90 value for wild-type HBV was 30 ±â€¯0.5 µM, whereas the IC90 values for CYE and CYEI mutants were 185 ±â€¯0.5 and 790 ±â€¯0.2 µM, respectively. Both tenofovir-resistant mutants and wild-type HBV had similar susceptibility to the capsid assembly modulator NVR 3-778 (IC50 <0.4 µM vs. IC50 = 0.4 µM, respectively). CONCLUSIONS: Our study reveals that the quadruple (CYEI) mutation increases the amount of tenofovir required to inhibit HBV by 15.3-fold in IC50 and 26.3-fold in IC90. These results demonstrate that tenofovir-resistant HBV mutants can emerge, although the genetic barrier is high. LAY SUMMARY: Tenofovir is the most potent nucleotide analogue for the treatment of chronic hepatitis B virus infection and there has been no hepatitis B virus mutation that confers >10-fold resistance to tenofovir up to 8 years. Herein, we identified, for the first time, a quadruple mutation that conferred 15.3-fold (IC50) and 26.3-fold (IC90) resistance to tenofovir in 2 patients who experienced viral breakthrough during tenofovir treatment.

Identification of novel genes associated with HIV-1 latency by analysis of histone modifications.

BACKGROUND: A reservoir of HIV-1 is a major obstacle in eliminating HIV-1 in patients because it can reactivate in stopping antiretroviral therapy (ART). Histone modifications, such as acetylation and methylation, play a critical role in the organization of chromatin domains and the up- or downregulation of gene expression. Although many studies have reported that an epigenetic mechanism is strongly involved in the maintenance of HIV-1 transcriptional latency, neither the epigenetic control of viral replication nor how HIV-1 latency is maintained is not fully understood. RESULTS: We re-analyzed a high throughput parallel DNA sequencing (ChIP-seq) data from previous work to investigate the effect of histone modifications, H3K4me3 and H3K9ac, on HIV-1 latency in terms of chromosome distribution. The outputs of ChIP-seq from uninfected CD4+ T cell lines and HIV-1 latently infected cells were aligned to hg18 using bowtie and then analyzed using various software packages. Certain chromosomes (16, 17, 19, and 22) were significantly enriched for histone modifications in both decreased and increased islands. In the same chromosomes in HIV-1 latently infected cells, 38 decreased and 41 increased islands from common islands of H3K4me3 and H3K9ac were selected for functional annotation. In Gene Ontology analysis, the 38 genes associated with decreased islands were involved in the regulation of biological process, regulation of cellular process, biological regulation, and purinergic receptor signaling pathway, while the 41 genes associated with increased islands were involved in nucleic acid binding, calcium-activated cation channel activity, DNA binding, and zinc ion binding. In Pathway Commons analysis, the 38 genes were strongly involved in the p63 transcription factor network, while the 41 genes were involved in the RNA polymerase III transcription termination pathway. Several genes such as Nuclear factor I X (NFIX) and TNF receptor association factor 4 (TRAF4) were selected as candidate genes for HIV latency. Especially, NFIX was highly expressed in HIV-1 latently infected cell lines and showed a dramatic reduction in expression after phorbol-13-myristate-12-acetate (PMA) treatment. CONCLUSIONS: These results show that the unique enrichment of histone modifications and its linked genes in specific chromosomes might play a critical role in the establishment and maintenance of HIV-1 latency.

Synergistic reactivation of latent HIV-1 provirus by PKA activator dibutyryl-cAMP in combination with an HDAC inhibitor.

HIV-1 reservoirs remain a major barrier to HIV-1 eradication. Although combination antiretroviral therapy (cART) can successfully reduce viral replication, it cannot reactivate HIV-1 provirus in this reservoir. Therefore, HIV-1 provirus reactivation strategies by cell activation or epigenetic modification are proposed for the eradication of HIV-1 reservoirs. Although treatment with the protein kinase A (PKA) activator cyclic AMP (cAMP) or epigenetic modifying agents such as histone deacetylase inhibitors (HDACi) alone can induce HIV-1 reactivation in latently infected cells, the synergism of these agents has not been fully evaluated. In the present study, we observed that treatment with 500µM of dibutyryl-cAMP, 1µM of vorinostat, or 1µM of trichostatin A alone effectively reactivated HIV-1 in both ACH2 and NCHA1 cells latently infected with HIV-1 without cytotoxicity. In addition, treatment with the PKA inhibitor KT5720 reduced the increased HIV-1 p24 level in the supernatant of these cells. After dibutyryl-cAMP treatment, we found an increased level of the PKA substrate phosphorylated cyclic AMP response element-binding protein. When we treated cells with a combination of dibutyryl-cAMP and vorinostat or trichostatin A, the levels of HIV-1 p24 in the supernatant and levels of intracellular HIV-1 p24 were dramatically increased in both ACH2 and NCHA1 cells compared with those treated with a single agent. These results suggest that combined treatment with a PKA activator and an HDACi is effective for reactivating HIV-1 in latently infected cells, and may be an important approach to eradicate HIV-1 reservoirs.

Highly activated p53 contributes to selectively increased apoptosis of latently HIV-1 infected cells upon treatment of anticancer drugs.

BACKGROUND: Despite the successful inhibition of human immunodeficiency virus type 1 (HIV-1) replication by combination antiretroviral therapy, cells latently infected with HIV-1 remaining in patients are a major obstacle for eradication of HIV-1 infection. The tumor suppressor factor p53 is activated by HIV-1 infection, and restricts HIV-1 replication. However, a therapeutic strategy based on p53 activity has not been considered for elimination of latently infected cells. METHODS: Apoptotic cells were analyzed using flow cytometry with anti-annexin A5-FITC Ab and PI staining upon treatment of anticancer drugs. The expression and activation of p53 and apoptotic molecules in latently HIV-1-infected T cells were compared using Western blot analysis. The role of p53 in the anticancer drug treatment-induced apoptosis of cells latently infected with HIV-1 was determined by knock-down experiment using siRNA against p53. RESULTS: Upon treatment with 5-fluorouracil (5-FU), apoptosis was increased in latently infected ACH2 cells encoding competent p53 compared with uninfected parent A3.01 cells, while the apoptosis of latently infected p53 null J1.1 cells was less than that of uninfected cells. Treatment with 5-FU increased the levels of cleaved caspase-3 and PARP in ACH2 cells compared with uninfected and latently infected p53 null J1.1 cells. The levels of expression and activation of p53 were higher in both latently infected ACH2 and NCHA2 cells than in uninfected cells. Furthermore, the activation levels of p53 in both cells were further increased upon 5-FU treatment. Consistent with p53 status, apoptosis was markedly increased in ACH2 and NCHA2 cells compared with uninfected and latently infected J1.1 cells upon treatment with other anticancer drugs such as doxorubicin and etoposide. Inhibition of p53 in cells with latent HIV-1 infection diminished apoptosis upon 5-FU treatment. CONCLUSION: Evidence described here indicate that when treated with anticancer drugs, apoptosis of cells with latent HIV-1 infection was increased via the p53 activation pathway and may provide information for application of anticancer drugs to selectively eliminate HIV-1 reservoirs.

Hypermethylation of the tumor-suppressor cell adhesion molecule 1 in human papillomavirus-transformed cervical carcinoma cells.

Epigenetic modification at CpG islands located on the promoter regions of tumor-suppressor genes has been associated with tumor development in many human cancers. Our study showed that the cell adhesion molecule 1 (CADM1) is downregulated in human papillomavirus (HPV)-infected cervical cancer cell lines via its hypermethylation and demethylation using 5-aza-2'-deoxycyticine (5-aza-dC) restored the expression of CADM1 protein. Overexpression of CADM1 inhibited cell proliferation. p53 was involved in the regulation of CADM1. Our results demonstrate that epigenetic alteration of CADM1 was more frequent in HPV-positive cervical cancers and that restoration of CADM1 expression may be a potential strategy for cervical cancer therapy.

NUCKS1, a novel Tat coactivator, plays a crucial role in HIV-1 replication by increasing Tat-mediated viral transcription on the HIV-1 LTR promoter.

BACKGROUND: Human immunodeficiency virus-1 (HIV-1) Tat protein plays an essential role in HIV gene transcription from the HIV-1 long terminal repeat (LTR) and replication. Transcriptional activity of Tat is modulated by several host factors, but the mechanism responsible for Tat regulation by host factors is not understood fully. RESULTS: Using a yeast two-hybrid screening system, we identified Nuclear ubiquitous casein and cyclin-dependent kinase substrate 1 (NUCKS1) as a novel Tat-interacting partner. Here, we report its function as a positive regulator of Tat. In a coimmunoprecipitation assay, HIV-1 Tat interacted sufficiently with both endogenous and ectopically expressed NUCKS1. In a reporter assay, ectopic expression of NUCKS1 significantly increased Tat-mediated transcription of the HIV-1 LTR, whereas knockdown of NUCKS1 by small interfering RNA diminished Tat-mediated transcription of the HIV-1 LTR. We also investigated which mechanism contributes to NUCKS1-mediated Tat activation. In a chromatin immunoprecipitation assay (ChIP), knockdown of NUCKS1 interrupted the accumulation of Tat in the transactivation-responsive (TAR) region on the LTR, which then led to suppression of viral replication. However, NUCKS1 expression did not increase Tat nuclear localization and interaction with Cyclin T1. Interestingly, the NUCKS1 expression level was lower in latently HIV-1-infected cells than in uninfected parent cells. Besides, expression level of NUCKS1 was markedly induced, which then facilitated HIV-1 reactivation in latently infected cells. CONCLUSION: Taken together, our data demonstrate clearly that NUCKS1 is a novel Tat coactivator that is required for Tat-mediated HIV-1 transcription and replication, and that it may contribute to HIV-1 reactivation in latently HIV-1 infected cells.

Double stranded aptamer-anchored reduced graphene oxide as target-specific nano detector.

Here, we report a double-stranded, dual-anchored, fluorescent aptamer on reduced graphene oxide (rGO) for the sensitive, selective, and speedy detection of a target protein in biological samples. This nano detector is composed of a target protein-specific fluorescent aptamer with BHQ1 as one anchoring moiety that forms double-stranded sequences with a complementary oligonucleotide sequence with BHQ1 as the other anchoring moiety, anchored to rGO nanosheets. The double-stranded and dual-anchored aptamer on rGO nanosheets (DAGO) exhibited 7.3-fold higher fluorescence intensities compared to a single-stranded, single-anchored fluorescent aptamer on rGO. As a model target protein, interferon-γ was used. DAGO detected the target protein, with linearity over a five-orders-of-magnitude concentration range (0.1 ng/ml-10 µg/ml) in buffer and human serum. DAGO was highly specific for the target protein, exhibiting little changes in fluorescence intensity in response to the non-target proteins, interleukin-2 and tumor necrosis factor-α. Moreover, DAGO allowed rapid quantification of the target protein in human immunodeficiency virus-positive patient serum samples. DAGO-based detection was complete in less than 10 min. Our results indicate that the DAGO provides new opportunities for the rapid and specific detection of target proteins in biological samples and could be widely applied to quantitate various target proteins by replacing the aptamer sequences.

Improvement in the performance of external quality assessment in Korean HIV clinical laboratories using unrecalcified human plasma.

BACKGROUND: The external quality assessment schemes (EQAS) organizer provides a suitable program to monitor and improve the quality of human immunodeficiency virus (HIV) testing laboratories with EQAS panels prepared under various conditions. The aim of the current study was to investigate the effects of human plasma samples on the EQAS results of HIV obtained from hospital-based clinical laboratories. METHODS: From 2007 to 2009, HIV EQAS panels consisted of four to six samples that consisted of undiluted positive and negative samples and were provided to laboratories twice per year. Up until the first half EQAS in 2008, EQAS panel materials were obtained by converting acid citrate dextrose treated plasma to serum via chemical treatment with CaCl2. Beginning with the second EQAS in 2008, all materials were prepared without the defibrination process. RESULTS: Approximately 300 HIV clinical laboratories participated in this program. The overall performance of clinical laboratories was shown to be improved when using unrecalcified plasma panels compared with recalcified panels. Significant differences were observed in EIA analyses of plasma for both positive (p<0.001) and negative (p<0.001) samples between the recalcified and unrecalcified groups. CONCLUSIONS: Our finding suggested that defibrination status of EQAS panels might affect the results of anti-HIV EQAS of Korean HIV testing laboratories.

Repression of porcine endogenous retrovirus infection by human APOBEC3 proteins.

It has been shown that porcine endogenous retrovirus (PERV) can infect human cells, indicating that PERV transmission poses a serious concern in pig-to-human xenotransplantation. A number of recent studies have reported on retrovirus interference by antiviral proteins. The most potent antiviral proteins are members of the APOBEC family of cytidine deaminases, which are involved in defense against retroviral attack. These proteins are present in the cytoplasm of mammalian cells and inhibit retroviral replication. To evaluate the inhibition of PERV transmission by human APOBEC3 proteins, we co-transfected 293T cells with a PERV molecular clone and human APOBEC3F or APOBEC3G expression vectors, and monitored PERV replication competency using a quantitative analysis of PERV pol genes. The replication of PERVs in cells co-expressing human APOBEC3s was reduced by 60-90% compared with PERV-only control. These results suggest that human APOBEC3G and APOBEC3F might serve a potential barrier function against PERV transmission in xenotransplantation.

Prevalence of human papillomavirus infection and genotype distribution among high-risk Korean women for prospecting the strategy of vaccine development.

We investigated the prevalence of human papillomavirus (HPV) infection and the distribution of high-risk HPV genotypes among 2,308 high-risk Korean women to predict how much the current prophylactic HPV vaccines might affect the prevention of cervical cancer in Korea. HPV DNA was detected in 939 women (40.7%) but only one-third of women were positive for HPV-16 and/or HPV-18, the genotypes used for developing the HPV vaccines. Thus, the development of area-specific HPV vaccines based on dominant HPV genotypes in our country is needed for preventing HPV infection and the development of premalignant lesions in the cervix of Korean women.

Distinctive distribution of HPV16 E6 D25E and E7 N29S intratypic Asian variants in Korean commercial sex workers.

The distribution of HPV16 sequence variations differs geographically and specific HPV16 E6 and E7 variants might carry a high risk for development of invasive cervical cancer and cervical intraepithelial neoplasia in a given population. To investigate the genetic variation of HPV 16 E6 and E7 genes, genomic DNAs from 56 HPV16-infected commercial sex workers were extracted from their cervical swabs by using DNA isolation kit. The E6 and E7 coding region (34-880) with HPV16 E6/E7 specific PCR were amplified and analyzed by using the DNAstar software. At the nucleotide level, 26 variants of the HPV16 E6 and E7 genes were identified including 12 silent mutations. At the amino acid level, the isolates showed 14 variants including E6 Q14H, E6 D25E, E6 I27R, E6 H78Y, E6 L83V, and E7 N29S. The dominant HPV16 E6 and E7 variants were HPV16 E6 D25E (68%) and HPV16 E7 N29S (73%), respectively, which belong to Asian lineage. Although this study has some limitations such as a small sample size and not enough clinical data, these finding suggests that the distinctive distribution of HPV 16 As-variant E6 D25E and E7 N29S might be associated with geographical dependence rather than disease progression. Further study is needed to determine the clinical and biological effects of these variants.

Genital human papillomavirus genotyping by HPV oligonucleotide microarray in Korean commercial sex workers.

Because of the diversity in human papillomavirus (HPV) distribution, according to the population and region, detailed investigations of HPV genotypes are important in designing more effective HPV vaccines for any given country. HPV DNA oligonucleotide microarray was used to investigate the distribution of HPV genotypes among commercial sex workers. The prevalence of HPV in Korean commercial sex workers was 47%, with HPV-16 and HPV-51 as the dominant genotypes. HPV subtypes in 148 commercial sex workers comprised 70 with one genotype, 42 with two genotypes, 17 with three genotypes, and 19 with four or more genotypes. HPV-40, the most dominant low-risk genotype, was not detected in single-infection commercial sex workers. All women with multiple infections of low-risk genotypes had the HPV-40 genotype. This molecular epidemiological study of genital HPV will be useful for the development of a favorable strategy to prevent the spread of this potentially serious infection.