Nanomaterials for Tumor Hypoxia Relief to Improve the Efficacy of ROS-Generated Cancer Therapy.

Given the fact that excessive levels of reactive oxygen species (ROS) induce damage to proteins, lipids, and DNA, various ROS-generating agents and strategies have been explored to induce cell death and tumor destruction by generating ROS above toxic threshold. Unfortunately, hypoxia in tumor microenvironment (TME) not only promotes tumor metastasis but also enhances tumor resistance to the ROS-generated cancer therapies, thus leading to ineffective therapeutic outcomes. A variety of nanotechnology-based approaches that generate or release O2 continuously to overcome hypoxia in TME have showed promising results to improve the efficacy of ROS-generated cancer therapy. In this minireview, we present an overview of current nanomaterial-based strategies for advanced cancer therapy by modulating the hypoxia in the TME and promoting ROS generation. Particular emphasis is put on the O2 supply capability and mechanism of these nanoplatforms. Future challenges and opportunities of design consideration are also discussed. We believe that this review may provide some useful inspiration for the design and construction of other advanced nanomaterials with O2 supply ability for overcoming the tumor hypoxia-associated resistance of ROS-mediated cancer therapy and thus promoting ROS-generated cancer therapeutics.

Peptide inhibitors of tembusu virus infection derived from the envelope protein.

The outbreak and spread of Tembusu virus (TMUV) has caused very large losses in the waterfowl-breeding industry since 2010. The viral envelope (E) protein, the principal surface protein of viral particles, plays a vital role in viral entry and fusion. In this study, two peptides derived from domain II (DII) and the stem of the TMUV envelope protein, TP1 and TP2, respectively, were tested for their antiviral activity. TP1 and TP2 inhibited TMUV infection in BHK-21 cells, and their 50% inhibitory concentrations (IC50) were 14.19 mg/L and 7.64 mg/L, respectively. Viral inhibition assays in different cell lines of avian origin showed that the inhibitory effects of TP1 and TP2 are not cell type dependent. Moreover, TP2 also exhibited inhibitory activity against Japanese encephalitis virus (JEV) infection. The two peptides inhibited antibody-mediated TMUV infection of duck peripheral blood lymphocytes. Co-immunoprecipitation assays and indirect enzyme-linked immunosorbent assays (ELISAs) indicated that both peptides interact with the surface of the TMUV virion. RNase digestion assays confirmed the release of viral RNA following incubation with TP1, while incubation with TP1 or TP2 interfered with the binding between TMUV and cells. Taken together, these results show that TP1 and TP2 may be developed into antiviral treatments against TMUV infection.

Transcriptomic profile of chicken bone marrow-derive dendritic cells in response to H9N2 avian influenza A virus.

Avian influenza subtype H9N2 infection is a mild but highly contagious disease that is associated with a decrease in the efficacy of vaccine interventions, and an increase in susceptibility to secondary infections in poultry. However, the immune evasion mechanism of H9N2 avian influenza viruses (AIVs) in chickens is poorly understood. Dendritic cells (DCs) are immune cells of major importance, involved in innate immune responses against viruses, but also in the setting of adaptive immune response due to their high ability to present viral antigen. Therefore, in the present study we used high-throughput RNA-sequencing technology at the transcriptome level to identify the differentially expressed genes (DEGs) between chicken DCs infected with H9N2 virus and mock-infected DCs. We identified 4151 upregulated DEGs and 2138 downregulated DEGs. Further enrichment analysis showed that the upregulated DEGs were enriched in the biological processes mainly involved in signal transduction, transmembrane transport, and innate immune/inflammatory responses. In contrast, the downregulated DEGs were associated with the biological processes mainly including metabolic process, and MHC class I antigen processing and presentation. In addition, 49 of these immune-related DEGs were validated by reverse transcription quantitative PCR (RT-qPCR). Collectively, these data suggest that H9N2 virus infection may enhance the signal transduction, and innate immune responses in chicken DCs, but impair their metabolic functions and antigen-presenting responses, which provide helpful insight into the pathogenesis of H9N2 AIVs in chickens and managing this infection in poultry farms.

The ubiquitin-proteasome system is necessary for the replication of duck Tembusu virus.

Duck Tembusu virus (DTMUV) is a newly emerging pathogenic flavivirus that has caused massive economic losses to the duck industry in China. The cellular factors required for DTMUV replication have been poorly studied. The ubiquitin-proteasome system (UPS), the major intracellular proteolytic pathway, mediates diverse cellular processes, including endocytosis and signal transduction, which may be involved in the entry of virus. In the present study, we explored the interplay between DTMUV replication and the UPS in BHK-21 cells and found that treatment with proteasome inhibitor (MG132 and lactacystin) significantly decreased the DTMUV progency at the early infection stage. We further revealed that inhibition of the UPS mainly occurs on the level of viral protein expression and RNA transcription. In addition, using specific siRNAs targeting ubiquitin reduces the production of viral progeny. In the presence of MG132 the staining for the envelope protein of DTMUV was dramatically reduced in comparison with the untreated control cells. Overall, our observations reveal an important role of the UPS in multiple steps of the DTMUV infection cycle and identify the UPS as a potential drug target to modulate the impact of DTMUV infection.

Identification and immunogenic evaluation of T cell epitopes based on tembusu virus envelope protein in ducks.

Newly emerging tembusu virus (TMUV) is a severe threat to poultry industry and causes huge economic losses. Humoral and cell-mediated immunity are both play vital roles in TMUV infection. Up to now, there has been no report on identification of T cell epitopes of the TMUV. In this work, we identified T cell epitopes within TMUV envelope (E) protein using synthesized peptides predicted in silico. A total of ten peptides could stimulate TMUV-specific T cells in murine ELISPOT and duck lymphocyte proliferation assay. Subsequently, DNA vaccine containing these T cell epitopes was constructed (pVAX-T) and the expression of multiepitope protein was confirmed by transfection of BHK-21 cells in vitro. Ducks were administrated intramusclarly to evaluated the immunologic effect of pVAX-T. In ducks immunized with pVAX-T, antibody against TMUV was undetectable, but the expression level of cytokines (IL-2, IL-6, IFN-γ) was upregulated both in peripheral blood lymphocytes and spleen. Furthermore, TMUV challenge revealed that cell-mediated immune response sitmulated by pVAX-T contributed to protection against TMUV infection. The identification of these T cell epitopes will contribute to designing epitope vaccine for preventing infection of TMUV and possibly provide the basis for further studies on cell-mediate immune response activated by TMUV.

Screening and identification of B-cell epitopes within envelope protein of tembusu virus.

BACKGROUND: Tembusu virus is a newly emerging flavivirus that caused egg-drop syndrome in ducks in China. TMUV envelope protein is a major structural protein locates at the surface of tembusu virus particle. During tembusu virus infection, envelope protein plays a pivotal role in induction of neutralizing antibody. However, B cell epitopes within envelope protein have not been well studied. METHOD: A series of 13 peptides derived from E protein of tembusu virus were synthesized and screened by Dot blot with tembusu virus-positive duck serum. Potential B-cell epitopes were respectively fused with GST tag and expressed in E. coli. The immunogenicity and protective efficiency of epitopes were assessed in ducks. RESULTS: Dot blot assay identified the peptides P21 (amino acids 301-329), P23 (amino acids 369-387), P27 (amino acids 464-471) and P28 (amino acids 482-496) as potential B-cell epitopes within the envelope protein of tembusu virus. Immunization of prokaryotically expressed epitopes elicited specific antibodies in ducks and the specific antibody elicited by P21, P27 and P28 could neutralized tembusu virus. In addition, protective test suggested that P21 and P27 could completely protect immunized ducks from TMUV challenge. CONCLUSION: Four potential B cell epiotpes within tembusu virus envelope protein were identified and analyzed in vitro and in vivo. It was demonstrated that two of them (P21 and P27) could elicit neutralizing antibodies in ducks and offer complete protection against tembusu virus challenge. This findings will contribute to the development of epitope vaccine for tembusu virus prevention.

Molecular cloning, characterization, and expression of duck 2'-5'-oligoadenylate synthetase-like gene.

2'-5'-Oligoadenylate synthetase-like protein (OASL) is an interferon-inducible antiviral protein that exerts antiviral effects through the RNase L- or retinoic acid-inducible gene I (RIG-I)-dependent signalling pathway. In this study, we identified and cloned the OASL gene (named duOASL) from healthy adult Cherry Valley ducks. Full-length duOASL cDNA (1630bp) encoded a 504-amino acid polypeptide containing three conserved domains, namely, nucleotidyltransferase domain, 2'-5'-oligoadenylate synthetase domain, and two ubiquitin-like repeats. DuOASL mRNA expression was quantified by performing quantitative reverse transcription-PCR (qRT-PCR). Results of qRT-PCR showed that duOASL was broadly expressed in all examined tissues, with the highest mRNA expression in the large intestine. Antiviral activity of duOASL was measured by determining its effect on Duck Tembusu virus (DTMUV) replication in vitro. We found that duOASL overexpression slightly inhibited DTMUV replication, whereas duOASL knockdown by using a specific small interfering RNA increased DTMUV replication in DF-1 cells. Thus, we successfully cloned and characterized the antiviral protein duOASL from Cherry Valley ducks and found that it exerted antiviral effects against DTMUV. These results provide a solid foundation for performing further studies to determine the mechanism underlying the antiviral effect of duOASL at the cellular level.

Domain I and II from newly emerging goose tembusu virus envelope protein functions as a dominant-negative inhibitor of virus infectivity.

Flavivirus envelope protein locates at the outermost surface of viral particle and mediates virus entry and fusion infection, and domains I and II of E protein play an important role in this process. In this study, we have expressed and purified goose tembusu virus (GTV) E protein domains I and II (DI/II) from E. coli, and tested conceptual approach that purified protein serves as anti-viral reagent. We found that DI/II inhibited GTV JS804 infection in BHK-21 cells in a dose-dependent manner, and this inhibition activity was achieved by binding to cell membrane specifically. Moreover, JS804 treated with DI/II specific anti-serum decreased its infectivity to BHK-21 cells. Taken together, this is first to show that the purified DI/II domain of tembusu virus expressed in E. coli was able to interfere with virus infection, which opens an avenue to develop novel anti-viral regents to prevent and eventually eradicate GTV infection.

Complete genome sequence of goose tembusu virus, isolated from jiangnan white geese in jiangsu, china.

Avian tembusu virus (TMUV), which was first identified in eastern China, is an emerging virus causing serious economic losses in the Chinese poultry industry. Here, we report the complete genome sequence of goose tembusu virus strain JS804, isolated from Jiangnan white geese with severe neurological signs. The genome of JS804 is 10,990 nucleotides (nt) in length and contains a single open reading frame encoding a putative polyprotein of 3,425 amino acids. Research of the whole sequence of tembusu virus will help us to understand further the molecular and evolutionary characteristics and pathogenesis of this virus.

Isolation and identification of a subgroup A avian leukosis virus from imported meat-type grand-parent chickens.

An exogenous avian leukosis virus (ALV) strain SDAU09C1 was isolated in DF-1 cells from one of 240 imported 1-day-old white meat-type grand parent breeder chicks. Inoculation of SDAU09C1 in ALV-free chickens induced antibody reactions specific to subgroup A or B. But gp85 amino acid sequence comparisons indicated that SDAU09C1 fell into subgroup A; it had homology of 88.8%-90.3% to 6 reference strains of subgroup A, much higher compared to other subgroups including subgroup B. This is the first report for ALV of subgroup A isolated from imported breeders.

[Isolation and identification of a subgroup B avian leukosis virus from chickens of Chinese native breed Luhua].

By inoculation of blood samples in DF-1 (C/E) cell culture, an exogenous avian leukosis virus (ALV) strain SDAU09C2 was isolated from a breeder farm of Chinese native breed "Luhua" in Shandong province. Comparisons of the amino acid sequence of env gene gp85 from the isolate with those from other ALV reference strains of different subgroups indicated that SDAU09C2 had the highest gp85 identity to two reference strains of subgroup B of 92.5%. Its gp85 identity to other chicken ALV subgroups A, C, D, E was in the range of 73.2%-87.9%. The identity to subgroup J was only 30.3%-32.4%. This is the first report on isolation and identification of ALV-B and its gp85 from Chinese native breed chickens.