Perceptions of Chinese Biomedical Researchers Towards Academic Misconduct: A Comparison Between 2015 and 2010.

Publications by Chinese researchers in scientific journals have dramatically increased over the past decade; however, academic misconduct also becomes more prevalent in the country. The aim of this prospective study was to understand the perceptions of Chinese biomedical researchers towards academic misconduct and the trend from 2010 to 2015. A questionnaire comprising 10 questions was designed and then validated by ten biomedical researchers in China. In the years 2010 and 2015, respectively, the questionnaire was sent as a survey to biomedical researchers at teaching hospitals, universities, and medical institutes in mainland China. Data were analyzed by the Chi squared test, one-way analysis of variance with the Tukey post hoc test, or Spearman's rank correlation method, where appropriate. The overall response rates in 2010 and 2015 were 4.5% (446/9986) and 5.5% (832/15,127), respectively. Data from 15 participants in 2010 were invalid, and analysis was thus performed for 1263 participants. Among the participants, 54.7% thought that academic misconduct was serious-to-extremely serious, and 71.2% believed that the Chinese authorities paid no or little attention to the academic misconduct. Moreover, 70.2 and 65.2% of participants considered that the punishment for academic misconduct at the authority and institution levels, respectively, was not appropriate or severe enough. Inappropriate authorship and plagiarism were the most common forms of academic misconduct. The most important factor underlying academic misconduct was the academic assessment system, as judged by 50.7% of the participants. Participants estimated that 40.1% (39.8 ± 23.5% in 2010; 40.2 ± 24.5% in 2015) of published scientific articles were associated with some form of academic misconduct. Their perceptions towards academic misconduct had not significantly changed over the 5 years. Reform of the academic assessment system should be the fundamental approach to tackling this problem in China.

Lytic infection of Kaposi's sarcoma-associated herpesvirus induces DNA double-strand breaks and impairs non-homologous end joining.

Kaposi's sarcoma-associated herpesvirus (KSHV) has been associated with the development of Kaposi's sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman's disease. Cytogenetic studies have revealed chromosome abnormalities in KS tissues, including recurring copy number changes in chromosomes and the loss of chromosomes. Unfaithful DNA repair may contribute to the genomic instability that is one of the most common hallmarks of tumours. We found that lytic infection of KSHV can cause severe DNA double-strand breaks (DSBs) and impair non-homologous end joining (NHEJ) in host cells. Processivity factor 8 (PF-8) of KSHV was identified as interacting with Ku70 and Ku86, and the interaction was dependent on DSBs and DNA. Overexpression of PF-8 in HeLa cells impaired NHEJ by blocking the interaction between the Ku complex and the DNA-dependent protein kinase catalytic subunit. These results suggest that KSHV lytic replication may contribute to tumorigenesis by causing DNA DSBs and interfering with the repair of DSBs.

Kaposi's sarcoma-associated herpesvirus processivity factor-8 dimerizes in cytoplasm before being translocated to nucleus.

The processivity factor-8 (PF-8) of Kaposi's sarcoma-associated herpesvirus (KSHV) plays an essential role in viral lytic replication. PF-8 forms homodimers in solution and is observed as a dimer on the DNA. Here, we show that PF-8 dimerizes in cells and that amino acid residues 1-21 and residues 277-304 of PF-8 (396R) are required for dimerization in vivo. Importantly, we demonstrate that PF-8 dimerizes in the cytoplasm before being translocated to the nucleus. The significance of PF-8 cytoplasmic dimerization as a possible first step in the formation of a prereplication complex is discussed.

Hepatitis C virus (HCV) NS2 protein up-regulates HCV IRES-dependent translation and down-regulates NS5B RdRp activity.

Chronic hepatitis C virus (HCV) infection often leads to liver cancer. The HCV NS2 protein is a hydrophobic transmembrane protein that associates with several cellular proteins in mammalian cells. In this report, we investigated the function of NS2 protein on HCV replication and translation by using a transient cell-based expression system. Cells co-transfected with pcDNA3.1 (-)-NS2 and the dual-luciferase reporter construct containing the HCV IRES were used to detect the effect of NS2 protein on HCV translation. Cells co-transfected with pcDNA3.1(-)-NS2, pcDNA-NS5B and a reporter plasmid were used to detect the effect of NS2 protein on HCV replication. The results showed that HCV NS2 protein up-regulated HCV IRES-dependent translation in a specific and dose-dependent manner in Huh7 cells but not in HeLa and HepG2 cells, and NS2 protein inhibited NS5B RdRp activity in a dose-independent manner in all three cell lines. These findings may suggest a novel mechanism by which HCV modulates its NS5B replication and IRES-dependent translation and facilitates virus persistence.

HCV NS2 protein inhibits cell proliferation and induces cell cycle arrest in the S-phase in mammalian cells through down-regulation of cyclin A expression.

Chronic hepatitis C virus (HCV) infection often leads to liver cancer. NS2 protein is a HCV hydrophobic transmembrane protein that associates with several cellular proteins in mammalian cells. In this report, we investigated the functions of NS2 protein by examining its effects on cell growth and cell cycle progression. Stable NS2-expressing HeLa and Vero cell lines were established by transfection of the cells with pcDNA3.1(-)-NS2 followed by selection of the transfected cells in the presence of G418. We found that the proliferation rates of both NS2-expressing cell lines were inhibited by 40-50% compared with the control cells that were transfected with pcDNA3.1(-) control vector. Cell cycle analysis of these NS2-expressing cell lines shows that the proportion of cells in the S-phase increased significantly compared to that of control cells that do not express NS2 protein, suggesting NS2 protein induces cell cycle arrest in the S-phase. Further studies showed that the induction of cell cycle arrest in the S-phase by NS2 protein is associated with the decrease of cyclin A level. In contrast, the expression of NS2 protein does not affect the levels of cyclin-dependent kinase CDK2, CDK4, cyclin D1, or cyclin E. Our results suggest that HCV NS2 protein inhibits cell growth and induces the cell cycle arrest in the S-phase through down-regulation of cyclin A expression, which may be beneficial to HCV viral replication. Our findings not only provide information in the understanding mechanism of HCV infection, but also provide guidance for the future development of potential therapeutics for the prevention and treatment of the viral infection.

Nuclear/nucleolar localization properties of C-terminal nucleocapsid protein of SARS coronavirus.

A novel coronavirus (CoV) has recently been identified as the aetiological agent of severe acute respiratory syndrome (SARS). Nucleocapsid (N) proteins of the Coronaviridae family have no discernable homology, but they share a common nucleolar-cytoplasmic distribution pattern. There are three putative nuclear localization signal (NLS) motifs present in the N. To determine the role of these putative NLSs in the intracellular localization of the SARS-CoV N, we performed a confocal microscopy analysis using rabbit anti-N antisera. In this report, we show that the wild type N was distributed mainly in the cytoplasm. The N-terminal of the N, which contains the NLS1 (aa38-44), was localized to the nucleus. The C-terminus of the N, which contains both NLS2 (aa257-265) and NLS3 (aa369-390) was localized to the cytoplasm and the nucleolus. Results derived from analysis of various deletion mutations show that the region containing amino acids 226-289 is able to mediate nucleolar localization. The deletion of two hydrophobic regions that flanked the NLS3 recovered its activity and localized to the nucleus. Furthermore, deletion of leucine rich region (220-LALLLLDRLNRL) resulted in the accumulation of N to the cytoplasm and nucleolus, and when fusing this peptide to EGFP localization was cytoplasmic, suggesting that the N may act as a shuttle protein. Differences in nuclear/nucleolar localization properties of N from other members of coronavirus family suggest a unique function for N, which may play an important role in the pathogenesis of SARS.

Hepatitis C virus non-structural 5A protein can enhance full-length core protein-induced nuclear factor-kappaB activation.

AIM: To study the effects of hepatitis C virus (HCV) core and non-structural 5A (NS5A) proteins on nuclear factor-kappaB (NF-kappaB) activity for understanding their biological function on chronic hepatitis caused by HCV infection. METHODS: Luciferase assay was used to measure the activity of NF-kappaB in three different cell lines cotransfected with a series of deletion mutants of core protein alone or together with NS5A protein using pNF-kappaB-Luc as a reporter plasmid. Western blot and indirect immunofluorescence assays were used to confirm the expression of proteins and to detect their subcellular localization, respectively. Furthermore, Western blot was also used to detect the expression levels of NF-kappaB/p65, NF-kappaB/p50, and inhibitor kappaB-a (IkappaB-a). RESULTS: The wild-type core protein (C191) and its mutant segments (C173 and C158) could activate NF-kappaB in Huh7 cells only and activation caused by (C191) could be enhanced by NS5A protein. Moreover, the full-length core protein and its different deletion mutants alone or together with NS5A protein did not enhance the expression level of NF-kappaB. The NF-kappaB activity was augmented due to the dissociation of NF-kappaB-IkappaB complex and the degradation of IkappaB-a. CONCLUSION: NF-kappaB is the key transcription factor that can activate many genes that are involved in the cellular immune response and inflammation. Coexpression of the full-length core protein along with NS5A can enhance the NF-kappaB activation, and this activation may play a significant role in chronic liver diseases including hepatocellular carcinoma associated with HCV infection.

The identification of three sizes of core proteins during the establishment of persistent hepatitis C virus infection in vitro.

Similar to Hepatitis C virus (HCV) infection in humans, HCVcc infection can also result in persistent and chronic infection. The core protein is a variable protein and exists in several sizes. Some sizes of core proteins have been reported to be related to chronic HCV infection. To study the possible role of the core protein in persistent HCV infection, a persistent HCVcc infection was established, and the expression of the core protein was analysed over the course of the infection. The results show that there are three sizes of core proteins (p24, p21 and p19) expressed during the establishment of persistent HCVcc infection. Of these, the p21 core protein is the mature form of the HCV core protein. The p24 core protein is the phosphorylated form of p21. The p19 core protein appears to be a functional by-product generated during the course of infection. These three core proteins are all localized in the cytoplasm and can be encapsidated into the HCV virion. The appearance of the p19 and p24 core proteins might be related to acute HCVcc infection and chronic infection respectively and may play an important role in the pathology of a HCV infection.

Germacrone inhibits early stages of influenza virus infection.

Highly pathogenic influenza viruses pose a serious public health threat to humans. Although vaccines are available, antivirals are needed to efficiently control disease progression and virus transmission due to the emergence of drug-resistant viral strains. In this study, germacrone, which is a major component of the essential oils extracted from Rhizoma Curcuma, was found to inhibit influenza virus replication. Germacrone showed antiviral activity against the H1N1 and H3N2 influenza A viruses and the influenza B virus in a dose-dependent manner. The viral protein expression, RNA synthesis and the production of infectious progeny viruses were decreased both in MDCK and A549 cells treated with germacrone. In a time-of-addition study, germacrone was found to exhibit an inhibitory effect on both the attachment/entry step and the early stages of the viral replication cycle. Germacrone also exhibited an effective protection of mice from lethal infection and reduced the virus titres in the lung. Furthermore, the combination of germacrone and oseltamivir exhibited an additive effect on the inhibition of influenza virus infection, both in vitro and in vivo. Our results suggest that germacrone may have the potential to be developed as a therapeutic agent alone or in combination with other agents for the treatment of influenza virus infection.

Oleanolic acid and ursolic acid: novel hepatitis C virus antivirals that inhibit NS5B activity.

Hepatitis C virus (HCV) infects up to 170 million people worldwide and causes significant morbidity and mortality. Unfortunately, current therapy is only curative in approximately 50% of HCV patients and has adverse side effects, which warrants the need to develop novel and effective antivirals against HCV. We have previously reported that the Chinese herb Fructus Ligustri Lucidi (FLL) directly inhibited HCV NS5B RNA-dependent RNA polymerase (RdRp) activity (Kong et al., 2007). In this study, we found that the FLL aqueous extract strongly suppressed HCV replication. Further high-performance liquid chromatography (HPLC) analysis combined with inhibitory assays indicates that oleanolic acid and ursolic acid are two antiviral components within FLL aqueous extract that significantly suppressed the replication of HCV genotype 1b replicon and HCV genotype 2a JFH1 virus. Moreover, oleanolic acid and ursolic acid exhibited anti-HCV activity at least partly through suppressing HCV NS5B RdRp activity as noncompetitive inhibitors. Therefore, our results for the first time demonstrated that natural products oleanolic acid and ursolic acid could be used as potential HCV antivirals that can be applied to clinic trials either as monotherapy or in combination with other HCV antivirals.

Fangchinoline inhibits human immunodeficiency virus type 1 replication by interfering with gp160 proteolytic processing.

The introduction of highly active antiretroviral therapy has led to a significant reduction in the morbidity and mortality of acquired immunodeficiency syndrome patients. However, the emergence of drug resistance has resulted in the failure of treatments in large numbers of patients and thus necessitates the development of new classes of anti-HIV drugs. In this study, more than 200 plant-derived small-molecule compounds were evaluated in a cell-based HIV-1 antiviral screen, resulting in the identification of a novel HIV-1 inhibitor (fangchinoline). Fangchinoline, a bisbenzylisoquinoline alkaloid isolated from Radix Stephaniae tetrandrae, exhibited antiviral activity against HIV-1 laboratory strains NL4-3, LAI and BaL in MT-4 and PM1 cells with a 50% effective concentration ranging from 0.8 to 1.7 µM. Mechanism-of-action studies showed that fangchinoline did not exhibit measurable antiviral activity in TZM-b1 cells but did inhibit the production of infectious virions in HIV-1 cDNA transfected 293T cells, which suggests that the compound targets a late event in infection cycle. Furthermore, the antiviral effect of fangchinoline seems to be HIV-1 envelope-dependent, as the production of infectious HIV-1 particles packaged with a heterologous envelope, the vesicular stomatitis virus G glycoprotein, was unaffected by fangchinoline. Western blot analysis of HIV envelope proteins expressed in transfected 293T cells and in isolated virions showed that fangchinoline inhibited HIV-1 gp160 processing, resulting in reduced envelope glycoprotein incorporation into nascent virions. Collectively, our results demonstrate that fangchinoline inhibits HIV-1 replication by interfering with gp160 proteolytic processing. Fangchinoline may serve as a starting point for developing a new HIV-1 therapeutic approach.

Liver X receptors agonists impede hepatitis C virus infection in an Idol-dependent manner.

Hepatitis C virus (HCV) is a major human pathogen that causes many serious diseases, including acute and chronic hepatitis, cirrhosis and hepatocellular carcinoma. Treatments for this virus are inadequate, and improved antiviral therapies are necessary. Although the precise mechanisms regulating HCV entry into hepatic cells are still unknown, the low-density lipoprotein receptor (LDLR) has been shown to be essential for entry of infectious HCV particles. Liver X receptors (LXR) were recently reported to control LDLR expression through the regulation of the expression of the Idol (inducible degrader of the LDLR) protein, which could trigger the ubiquitination and degradation of LDLR. In this study, we analyzed the antiviral effect of Idol in vitro. The results demonstrated that Huh7.5.1 cells that exogenously expressed Idol were resistant to HCV infection. Next, the treatment of HCV-infected Huh7.5.1 cells with either synthetic LXR agonists (GW3965 or T0901317) or the natural LXR ligand 24(S),25-epoxycholesterol inhibited HCV infection in a dose-dependent manner. Furthermore, a combination of LXR agonists and HCV RNA replication inhibitors exerted additive effects against HCV, as revealed by isobologram analysis. In conclusion, our data indicate that molecules such as LXR agonists, which could stimulate the expression of Idol, represent a new class of potential anti-HCV compounds, and these compounds could be developed for therapeutic use against HCV infection, either as a monotherapy, or in combination with other anti-HCV drugs.

Kaposi's sarcoma-associated herpesvirus-encoded LANA down-regulates IL-22R1 expression through a cis-acting element within the promoter region.

Kaposi's sarcoma-associated herpesvirus (KSHV) is considered to be a necessary, but not sufficient, causal agent of Kaposi's sarcoma (KS). All forms of KS are characterized by the proliferation of spindle-shaped cells, and most (>90%) spindle cells from KS lesions are latently infected with KSHV. During KSHV latency, only a few viral genes are expressed. Among those latent genes, the ORF 73 gene encodes the latency-associated nuclear antigen (LANA), which is critical for the establishment and maintenance of the latent KSHV infection. Much evidence suggests that many cytokines can increase the frequency and aggressiveness of KS. In this study, a microarray analysis of KS and normal tissues revealed that multiple cytokines and cytokine receptors are regulated by KSHV latent infection. Of special interest, IL-22R1 transcript level was found to be down-regulated in the KS tissue. To study the possible regulation of IL-22R1 by LANA, the IL-22R1 promoter was constructed and found to contain a LANA-binding site (LBS). LANA was demonstrated to down-regulate IL-22R1 expression via direct binding to the LBS located within the IL-22R1 promoter region. Furthermore, KSHV latently infected cells showed an impaired response to IL-22 stimulation. These results suggest that LANA can regulate host factor expression by directly binding to a cis-acting element within the factor's promoter to benefit latent viral infection and suppression of the antiviral immune response.

A novel luciferase and GFP dual reporter virus for rapid and convenient evaluation of hepatitis C virus replication.

Herein, we describe the development of a monocistronic dual reporter virus for monitoring hepatitis C virus (HCV) replication. The recombinant construct encodes for the humanized Renilla luciferase (hRLuc) reporter gene inserted upstream of the viral open reading frame and a green fluorescent protein (GFP) gene inserted into the C-terminus of non-structural protein 5A (NS5A) of the JFH1 viral genome. The viral RNA replicated efficiently in transfected cells and infectious virions could be produced without obvious attenuation of viral replication. The viral titer of the dual reporter virus was comparable to that of single reporter viruses. The expression levels of these two reporter genes correlated well with HCV replication in the presence or absence of antiviral agents. Moreover, because of the direct visibility of GFP fluorescence and the correlation between GFP positive cell numbers and hRLuc activity, the optimal time for measuring hRLuc activity was determined. This novel infectious system is a time saving and cost effective method for studying the interaction between viruses and host cells as well as for screening anti-HCV drugs.

Epigallocatechin gallate inhibits HBV DNA synthesis in a viral replication - inducible cell line.

AIM: To analyze the antiviral mechanism of Epigallocatechin gallate (EGCG) against hepatitis B virus (HBV) replication. METHODS: In this research, the HBV-replicating cell line HepG2.117 was used to investigate the antiviral mechanism of EGCG. Cytotoxicity of EGCG was analyzed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Hepatitis B virus e antigen (HBeAg) and hepatitis B virus surface antigen (HBsAg) in the supernatant were detected by enzyme-linked immunosorbent assay. Precore mRNA and pregenomic RNA (pgRNA) levels were determined by semi-quantitative reverse transcription polymerase chain reaction (PCR) assay. The effect of EGCG on HBV core promoter activity was measured by dual luciferase reporter assay. HBV covalently closed circular DNA and replicative intermediates of DNA were quantified by real-time PCR assay. RESULTS: When HepG2.117 cells were grown in the presence of EGCG, the expression of HBeAg was suppressed, however, the expression of HBsAg was not affected. HBV precore mRNA level was also down-regulated by EGCG, while the transcription of precore mRNA was not impaired. The synthesis of both HBV covalently closed circular DNA and replicative intermediates of DNA were reduced by EGCG treatment to a similar extent, however, HBV pgRNA transcripted from chromosome-integrated HBV genome was not affected by EGCG treatment, indicating that EGCG targets only replicative intermediates of DNA synthesis. CONCLUSION: In HepG2.117 cells, EGCG inhibits HBV replication by impairing HBV replicative intermediates of DNA synthesis and such inhibition results in reduced production of HBV covalently closed circular DNA.

Expression, purification and immunogenic characterization of hepatitis C virus recombinant E1E2 protein expressed by Pichia pastoris yeast.

Development of an effective vaccine may be the key in the control of hepatitis C virus (HCV) infection. Recent studies have shown that HCV envelope proteins can induce broadly neutralizing antibodies against conserved domain for HCV binding to the cellular receptors. So HCV envelope proteins are considered as the major HCV vaccine candidate. In this study, we used Pichia pastoris yeast to express truncated HCV E1E2 protein, which consists of E1 residues 187-346 and E2 residues 381-699. The yeast can produce high level of recombinant HCV E1E2 protein. The protein has complex glycosylation and can bind to CD81, the putative HCV receptor. Moreover, the purified protein can efficiently induce anti-E1E2 antibodies in rabbits, which are able to neutralize two kinds of HCV pseudotype particles derived from HCV genotype 1a and 1b, as well as HCV virions derived from HCV genotype 2a. These findings indicate that the recombinant E1E2 glycoprotein is effective in inducing broadly neutralizing antibodies, and is a potent HCV vaccine candidate.

Activation of NF-kappaB by the full-length nucleocapsid protein of the SARS coronavirus.

The severe acute respiratory syndrome coronavirus (SARS-CoV) is the major causative agent for the worldwide outbreak of SARS in 2003. The mechanism by which SARS-CoV causes atypical pneumonia remains unclear. The nuclear factor kappa B (NF-kappaB) is a key transcription factor that activates numerous genes involved in cellular immune response and inflammation. Many studies have shown that NF-kappaB plays an important role in the pathogenesis of lung diseases. In this study, we investigated the possible regulatory interaction between the SARS-CoV nucleocapsid (N) protein and NF-kappaB by luciferase activity assay. Our results showed that the SARS-CoV N protein can significantly activate NF-kappaB only in Vero E6 cells, which are susceptible to SARS-CoV infection, but not in Vero or HeLa cells. This suggests that NF-kappaB activation is cell-specific. Furthermore, NF-kappaB activation in Vero E6 cells expressing the N protein is dose-dependent. Further experiments showed that there is more than one function domain in the N protein responsible for NF-kappaB activation. Our data indicated the possible role of the N protein in the pathogenesis of SARS.