Tembusu virus in human, China

SUMMARY

Tembusu virus (TMUV) infection in ducks, geese and house sparrows was reported in China. To confirm the emergence of TMUV in humans, we investigated TMUV as a possible infection in duck industry workers in Shandong, China. Of 132 serum samples tested, 95 (71.9%) had TMUV antibodies. In oral swabs detection, 63 (47.7%) samples were positive for TMUV RNA. Nucleotide sequences of 277 bp coding the partial NS3 protein showed more than 99.5% identity with other duck TMUV strains, which can cause severe egg drop in ducks. These findings contribute to the realization that TMUV may be overlooked as a zoonotic transmission in China.

Characterization of a Tembusu virus isolated from naturally infected house sparrows (Passer domesticus) in Northern China

The house sparrow (Passer domesticus) is one of the most widely distributed wild birds in China. Tembusu virus (TMUV) strain, TMUV-SDHS, was isolated from house sparrows living around the poultry farms in Shandong Province, Northern China. Genetic analysis of E and NS5 genes showed that it had a close relationship with that of the YY5 strain, which can cause severe egg drop in ducks. Pathogenicity studies showed that the virus is highly virulent when experimentally inoculated into the ducks. These findings show that house sparrows carrying the Tembusu virus may play an important role in transmitting the virus among other species.

Analysis of the complete genome of Tembusu virus, a flavivirus isolated from ducks in China

During investigations into the outbreak of duck viral infection in 2010 in China, with a severe drop in egg production, a flavivirus was isolated from the affected ducks. It was characterized as a Tembusu virus (TMUV). In this study, we obtained a complete genome sequence of Tembusu virus using RT-PCR and RACE techniques. TMUV genome is a singled-stranded RNA, with 10,990 nucleotides in length, and contains a single open reading frame (3410 amino acids) encoding 11 viral proteins with 5'and 3'non-translated regions (NTRs) of 142 and 618 nt, respectively. We characterized the open reading frame (ORF) with respect to gene sizes, cleavage sites and potential glycosylation sites. The different genomic regions of the virus were also compared with those of six other flaviviruses including Japanese encephalitis virus, West Nile virus (WNV), dengue-2 virus, yellow fever virus, tick-borne encephalitis virus (TBEV) and Bagaza virus. TMUV demonstrated the highest similarity to Bagaza virus. The result of entire ORF scanning shows that TMUV was close to Bagaza viruses in genetic relatedness. These data demonstrate that TMUV is a unique virus among the mosquito-borne flaviviruses and also provide a useful reference for a critically important study to determine why TMUV is a serious pathogen for ducks.

Isolation and genetic characterization of a tembusu virus strain isolated from mosquitoes in Shandong, China

Tembusu virus (TMUV) is a flavivirus, presumed to be a mosquito-borne flavivirus of the Ntaya virus subgroup. To date, however, there have been no reports indicating that mosquitoes are involved in the spread of TMUV. In this study, we report the first isolation of TMUV from Culex mosquitoes. We describe the isolation and characterization of a field strain of TMUV from mosquitoes collected in Shandong Province, China. The virus isolate, named TMUV-SDMS, grows well in mosquito cell line C6/36, in Vero and duck embryo fibroblast (DEF) cell lines, and causes significant cytopathic effects in these cell cultures. The TMUV-SDMS genome is a single-stranded RNA, 10 989 nt in length, consisting of a single open reading frame encoding a polyprotein of 3410 amino acids, with 5' and 3' untranslated regions of 142 and 617 nt, respectively. Phylogenetic analysis of the E and NS5 genes revealed that the TMUV-SDMS is closely related to the TMUV YY5 and BYD strains which cause severe egg-drop in ducks. The 3'NTR of TMUV-SDMS contains two pairs of tandem repeat CS and one non-duplicate CS, which have sequence similarities to the same repeats in the YY5 and BYD strains. Our findings indicate that mosquitoes carrying the TMUV may play an important role in the spread of this virus and in disease outbreak.

Increased Expression of MicroRNA-221 in gastric cancer and its clinical significance

OBJECTIVE

MicroRNA-221 (miR-221), which is located on chromosome X, is an oncogenic microRNA that is involved in several human malignancies. This study aimed to characterize the role of miR-221 in the initiation and malignant progression of gastric cancer.

METHODS

The level of miR-221 expression in 92 pairs of primary gastric tumour tissue and adjacent nontumour tissue was quantified by real-time reverse transcription-polymerase chain reaction. The relationship between the miR-221 level and clinicopathological features was explored.

RESULTS

MiR-221 was up-regulated in 88% (81/92) of gastric cancer tissue samples compared with their paired adjacent nontumour tissue samples. High expression of miR-221 showed a significant correlation with advanced tumour-node-metastasis stage, local invasion and lymphatic metastasis. Univariate and multivariate Cox proportional hazard regression analyses revealed that miR-221 overexpression was an unfavourable prognostic factor for overall survival in patients with gastric cancer.

CONCLUSIONS

These findings suggest that miR-221 is a novel prognostic indicator in gastric cancer and may be a potential target for diagnosis and gene therapy.

Using pseudo amino acid composition to predict transmembrane regions in protein: cellular automata and Lempel-Ziv complexity

Transmembrane (TM) proteins represent about 20-30% of the protein sequences in higher eukaryotes, playing important roles across a range of cellular functions. Moreover, knowledge about topology of these proteins often provides crucial hints toward their function. Due to the difficulties in experimental structure determinations of TM protein, theoretical prediction methods are highly preferred in identifying the topology of newly found ones according to their primary sequences, useful in both basic research and drug discovery. In this paper, based on the concept of pseudo amino acid composition (PseAA) that can incorporate sequence-order information of a protein sequence so as to remarkably enhance the power of discrete models (Chou, K. C., Proteins: Structure, Function, and Genetics, 2001, 43: 246-255), cellular automata and Lempel-Ziv complexity are introduced to predict the TM regions of integral membrane proteins including both alpha-helical and beta-barrel membrane proteins, validated by jackknife test. The result thus obtained is quite promising, which indicates that the current approach might be a quite potential high throughput tool in the post-genomic era. The source code and dataset are available for academic users at liml@scu.edu.cn.

Evidence for Vertical Transmission of Novel Duck-Origin Goose Parvovirus-Related Parvovirus

In 2015, novel duck-origin goose parvovirus-related parvovirus (N-GPV) infection progressively appeared in commercial Cherry Valley duck flocks in North China. Diseased ducks were observed to have beak atrophy and dwarfism syndrome (BADS). A previous study showed that a high seropositive rate for N-GPV indicated a latent infection in most breeder duck flocks. To investigate this possibility in hatching eggs collected from N-GPV-infected breeder ducks, 120 eggs were collected at various stages of embryonic development for viral DNA detection and an N-GPV-specific antibody test. N-GPV DNA was present in nine hatching eggs, eleven duck embryo and eight newly hatched ducklings. Of the newly hatched ducklings, 58.33% (21/36) were seropositive. Further, two isolates were obtained from a 12-day-old duck embryo and a newly hatched duckling. N-GPV infection did not reduce the fertilization rate and hatchability. These results indicate possible vertical transmission of N-GPV and suggest that it may be transmitted from breeder ducks to ducklings in ovo.

LysGH15B, the SH3b domain of staphylococcal phage endolysin LysGH15, retains high affinity to staphylococci

LysGH15, a phage endolysin, exhibits a particularly broad lytic spectrum against Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA). Sequence analysis reveals that this endolysin contains a C-terminal cell wall binding domain (SH3b), which causes the endolysin to bind to host strains. In this study, the substrate binding affinity of the SH3b domain (LysGH15B) was evaluated. A fusion protein of LysGH15B and green fluorescent protein (LysGH15B-GFP) were cloned and expressed in Escherichia coli. Laser scanning confocal microscopy was used to detect the fluorescence of the treated cells irradiated at different excitation wavelengths and to determine the binding activity of LysGH15B-GFP and GFP. We found that LysGH15B-GFP not only generated green fluorescence, but, more importantly, also displayed specific affinity to staphylococcal isolates, especially MRSA. In contrast, the single GFP did not display any binding activity. The high affinity was attributed to the portion of LysGH15B and the binding activity of the fusion protein was specific to staphylococci. This study provides an insight into the SH3b domain of LysGH15. The specific binding activity may cause LysGH15B to serve as an anchoring device, and offer an alternative approach for cell surface attachment onto staphylococci.

Epidemiological investigation of H9 avian influenza virus, Newcastle disease virus, Tembusu virus, goose parvovirus and goose circovirus infection of geese in China

To deepen the knowledge about epidemic prevalence in the goose breeding field, a triplex PCR assay was established, and 478 samples were collected from scaled goose farms in 11 provinces in China. The results of this epidemiological investigation showed that incidence rates of H9 avian influenza and goose circovirus were the highest among five infectious diseases that were evaluated. In addition, the triplex PCR assay established remarkable sensitivity, rapidity and versatility compared to other diagnostic methods. Dual infection comprised a large proportion of the co-infections in the field, of which the combinations of H9/Tembusu, H9/goose circovirus and goose circovirus/Tembusu co-infected cases were more common. Epidemics were more severe in winter and spring. Additionally, significant differences in the prevalence of these infectious diseases were observed in association with different age groups. In addition, phylogenetic analysis, determined by the neighbour-joining method, was carried out to investigate the evolution of these viruses during the study period. For the most part, virus strains isolated during the study were consistent with most goose-origin strains isolated from the Chinese mainland over the past few years. However, mutations were observed between isolated H9 avian influenza virus strains and sequences available from GenBank, which should draw much attention.

Synthetic Toll-like receptor 7 ligand inhibits porcine reproductive and respiratory syndrome virus infection in primary porcine alveolar macrophages

Porcine reproductive and respiratory syndrome virus (PRRSV), a common viral pathogen, causes huge annual economic losses to the swine industry worldwide. After triggering by specific ligands, the Toll-like receptor 7 (TLR7), a type of pattern-recognition receptor (PRR), induces antiviral cytokines production. Previously, we synthesized an adenine analog, designated SZU101, a TLR7-specific ligand. In this study, we assessed the inhibitory effect of SZU101 on PRRSV infection in vitro. SZU101 significantly suppressed PRRSV infection in primary porcine alveolar macrophages (PAMs) in a dose-dependent manner. Moreover, SZU101-induced inhibition involved NF-κB pathway activation in PAMs to initiate expression of TLR7-mediated cytokines and induce expression of downstream signaling IFN-stimulated genes (ISGs). Chloroquine, a TLR7 inhibitor, and BAY 11-7082, an NF-κB inhibitor, reversed both the SZU101-induced antiviral effect and induction of cytokine genes and ISGs expression. Therefore, SZU101 antiviral effects depend at least in part on TLR7-NF-κB signaling pathway. Additionally, administration of SZU101 enhanced the humoral and cell-mediated immune responses against PRRSV antigens in mice. Given these results, SZU101 holds promise as an antiviral agent and a vaccine adjuvant to prevent PRRSV infection in pigs.

Conjugation of toll-like receptor-7 agonist to gastric cancer antigen MG7-Ag exerts antitumor effects

AIM: To investigate the effects of our tumor vaccines on reversing immune tolerance and generating therapeutic response.

METHODS: Vaccines were synthesized by solid phase using an Fmoc strategy, where a small molecule toll-like receptor-7 agonist (T7) was conjugated to a monoclonal gastric cancer 7 antigen mono-epitope (T7-MG1) or tri-epitope (T7-MG3). Cytokines were measured in both mouse bone marrow dendritic cells and mouse spleen lymphocytes after exposed to the vaccines. BALB/c mice were intraperitoneally immunized with the vaccines every 2 wk for a total of three times, and then subcutaneously challenged with Ehrlich ascites carcinoma (EAC) cells. Three weeks later, the mice were killed, and the tumors were surgically removed and weighed. Serum samples were collected from the mice, and antibody titers were determined by ELISA using an alkaline phosphate-conjugated detection antibody for total IgG. Antibody-dependent cell-mediated cytotoxicity was detected by the lactate dehydrogenase method using natural killer cells as effectors and antibody-labeled EAC cells as targets. Cytotoxic T lymphocyte activities were also detected by the lactate dehydrogenase method using lymphocytes as effectors and EAC cells as targets.

RESULTS: Vaccines were successfully synthesized and validated by analytical high performance liquid chromatography and electrospray mass spectrometry, including T7, T7-MG1, and T7-MG3. Rapid inductions of tumor necrosis factor-α and interleukin-12 in bone marrow dendritic cells and interferon γ and interleukin-12 in lymphocytes occurred in vitro after T7, T7-MG1, and T7-MG3 treatment. Immunization with T7-MG3 reduced the EAC tumor burden in BALB/c mice to 62.64% ± 5.55% compared with PBS control (P < 0.01). Six or nine weeks after the first immunization, the monoclonal gastric cancer 7 antigen antibody increased significantly in the T7-MG3 group compared with the PBS control (P < 0.01). As for antibody-dependent cell-mediated cytotoxicity, antisera obtained by immunization with T7-MG3 were able to markedly enhance cell lysis compared to PBS control (31.58% ± 2.94% vs 18.02% ± 2.26%; P < 0.01). As for cytotoxic T lymphocytes, T7-MG3 exhibited obviously greater cytotoxicity compared with PBS control (40.92% ± 4.38% vs 16.29% ± 1.90%; P < 0.01).

CONCLUSION: A successful method is confirmed for the design of gastric cancer vaccines by chemical conjugation of T7 and multi-repeat-epitope of monoclonal gastric cancer 7 antigen.

Synthetic MUC1 breast cancer vaccine containing a Toll-like receptor 7 agonist exerts antitumor effects

Adjuvant immunotherapy has recently emerged as a potential treatment strategy for breast cancer. The tumor-associated protein mucin 1 (MUC1) has received increasing attention due to its high expression in numerous types of common tumors, in which MUC1 acts as a cancer antigen. However, the simple mixed composition of an adjuvant and a peptide is not a sufficient rationale for a MUC1 peptide-based vaccine. The present study developed a novel Toll-like receptor 7 (TLR7) agonist-conjugated MUC1 peptide vaccine (T7-MUC1), which elicited an effective immune response and a robust antitumor effect in a mouse breast cancer model. In vitro, T7-MUC1 significantly increased the release of cytokines in mouse bone marrow dendritic cells and spleen lymphocytes, and induced the dendritic cell-cytokine-induced killer response against tumor cells with high MUC1 expression. In vivo, it was observed that the 4T1 tumor weights in mice immunized with the T7-MUC1 conjugate were reduced by ≥70% compared with those in the control group. Furthermore, the therapeutic responses in vivo were attributed to the increase in specific humoral and cellular immunity, including high antibody titers, antibody-dependent cell-mediated cytotoxicity and cytotoxic T-lymphocyte activity. The percentages of CD3⁺/CD8⁺ T-cells were significantly higher in the T7-MUC1 treatment group compared with those in the control group. Therefore, the results of the present study suggested that the T7-MUC1 vaccine inhibited tumor growth in mice and thus may have potential as a therapeutic candidate in clinical trials for breast cancer immunotherapy.

Knockdown of Notch1 inhibits nasopharyngeal carcinoma cell growth and metastasis via downregulation of CCL2, CXCL16, and uPA

Notch pathway is a highly conserved cell signaling system that plays very important roles in controlling multiple cell differentiation processes during embryonic and adult life. Multiple lines of evidence support the oncogenic role of Notch signaling in several human solid cancers; however, the pleiotropic effects and molecular mechanisms of Notch signaling inhibition on nasopharyngeal carcinoma (NPC) remain unclear. In this study, we evaluated Notch1 expression in NPC cell lines (CNE1, CNE2, SUNE1, HONE1, and HK1) by real-time quantitative PCR and Western blot analysis, and we found that CNE1 and CNE2 cells expressed a higher level of Notch1 compared with HONE1, SUNE1, and HK1 cells. Then Notch1 expression was specifically knocked down in CNE1 and CNE2 cells by Notch1 short hairpin RNA (shRNA). In Notch1 knockdown cells, cell proliferation, migration, and invasion were significantly inhibited. The epithelial-mesenchymal transition of tumor cells was reversed in Notch1-shRNA-transfected cells, accompanied by epithelioid-like morphology changes, increased protein levels of E-cadherin, and decreased expression of vimentin. In addition, knockdown of Notch1 markedly inhibited the expression of urokinase plasminogen activator (uPA) and its receptor uPAR, and chemokines C-C motif chemokine ligand 2 and C-X-C motif chemokine ligand 16, indicating that these factors are downstream targets of Notch1. Furthermore, deleting uPA expression had similar effects as Notch1. Finally, knockdown of Notch1 significantly diminished CNE1 cell growth in a murine model concomitant with inhibition of cell proliferation and induction of apoptosis. These results suggest that Notch1 may become a novel therapeutic target for the clinical treatment of NPC.

Gastric cancer vaccines synthesized using a TLR7 agonist and their synergistic antitumor effects with 5-fluorouracil

Background

Vaccines play increasingly important roles in cancer treatment due to their advantages of effective targeting and few side effects. Our laboratory has attempted to construct vaccines by conjugating TLR7 agonists with tumor-associated antigens. Furthermore, immunochemotherapy has recently become an appealing approach to cancer therapy. 5-fluorouracil (5-FU), a commonly used chemotherapeutic agent, can reportedly potently and selectively kill tumor-associated MDSCs in vivo.

Methods

Gastric cancer vaccines were synthesized by the covalent attachment of our TLR7 agonist with the gastric cancer antigen MG7-Ag tetra-epitope, leading to T7 − ML (linear tetra-epitope) and T7 − MB (branched tetra-epitope). Cytokines induced by the vaccines in vitro were assessed by ELISA. A tumor challenge model was created by treating BALB/c mice on either a prophylactic or therapeutic vaccination schedule. 5-FU was simultaneously applied to mice in the combination treatment group. CTL and ADCC activities were determined by the LDH method, while CD3⁺/CD8⁺, CD3⁺/CD4⁺ T cells and MDSCs were evaluated by flow cytometry.

Results

In vitro, rapid TNF-α and IL-12 inductions occurred in BMDCs treated with the vaccines. In vivo, among all the vaccines tested, T7 − MB most effectively reduced EAC tumor burdens and induced CTLs, antibodies and ADCC activity in BALB/c mice. Immunization with T7 − MB in combination with 5-FU chemotherapy reduced tumor sizes and extended long-term survival rates, mainly by improving T cell responses, including CTLs, CD3⁺/CD8⁺ and CD3⁺/CD4⁺ T cells. 5-FU also enhanced the T7 − MB efficiency by reversing immunosuppressive factors, i.e., MDSCs, which could not be validly inhibited by the vaccines alone. In addition, T7 − MB repressed tumor growth and immune tolerance when the therapeutic schedule was used, although the effects were weaker than those achieved with either T7 − MB alone or in combination with 5-FU on the prophylactic schedule.

Conclusions

A novel effective gastric cancer vaccine was constructed, and the importance of branched multiple antigen peptides and chemical conjugation to vaccine design were confirmed. The synergistic effects and mechanisms of T7 − MB and 5-FU were also established, observing mainly T cell activation and MDSC inhibition.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1501-z) contains supplementary material, which is available to authorized users.

Recombinant human kallistatin inhibits angiogenesis by blocking VEGF signaling pathway

Kallistatin has been recognized as an endogenous angiogenic inhibitor. However, the underlying molecular mechanism remains poorly understood. Taking it into account that vascular endothelial growth factor (VEGF) has been implicated in all aspects of normal and pathological vasculogenesis and angiogenesis. In this study, we investigated whether VEGF signaling pathway was impacted by the anti-angiogenic effect of recombinant human kallistatin (rhKal). We found that the rhKal inhibited proliferation as well as induced apoptosis of cultured human umbilical vein endothelial cells (HUVECs) in both concentration- and time-dependent manners. The rhKal also suppressed the VEGF-induced migration and tube formation of HUVECs. Furthermore, our data revealed that the rhKal suppressed the VEGF165-stimulated tyrosine phosphorylation of VEGFR-2 as well as its downstream signal molecular activation. The inhibition of receptor phosphorylation was correlated with a decrease in VEGF-triggered phosphorylation of angiogenesis signal molecules AKT and ERK, but not stress-related JNK. Taken together, these findings added the knowledge for us to understand the anti-angiogenic mechanism of kallistatin, which suggested that the rhKal could be worth as a candidate compound for further development for the purpose of anti-angiogenic therapies.

Subtractive screening with the Mycobacterium tuberculosis surface protein phage display library

Surface proteins consist of secreted and membrane proteins and play a central role in the interaction of the pathogen with its environment, especially in the pathogenicity of Mycobacterium tuberculosis (MTB). Research on surface proteins in MTB has focused on 2D electrophoresis of culture filtrate proteins (CFP), extraction of transmembrane proteins with detergent and predicting their properties with a range of available algorithms. However, functional analysis of these secretomes is possible only if many proteins are expressed and purified individually, which limits a large number of studies to the function of the proteome. Here, we utilized a phage display system to construct a whole genomic surface protein phage display library of MTB, which can complete direct selection, identification, expression, purification and functional research of surface proteins of MTB. With this system we made a new serological approach involving iterative subtraction screening. Cross-reactivity of antibodies was reduced by preadsorption of the surface protein phage display library with the sera of healthy BCG-vaccinated individuals prior to studying their reactivity against the sera of tuberculosis (TB) patients. As a result six antigens were identified, three of which have not previously been reported as diagnosis antigens. The surface protein phage display library shows great promise in the study of MTB.

Synergistic apoptosis-inducing effect of aspirin and isosorbide mononitrate on human colon cancer cells

Aspirin and isosorbide mononitrate (ISMN) are two commonly used drugs, which are clinically applied for the treatment of inflammatory and cardiovascular diseases, respectively. Recently, aspirin has attracted interest due to its potential application for the treatment of cancer, particularly colon cancer. NO-aspirin, an aspirin derivative containing a covalently bound NO-donating moiety, has been proven to be an effective anti‑tumor agent with apoptosis-inducing ability. In the present study, ISMN was used as an NO donor and its synergic effect with aspirin was assessed in human colon cancer cells. In vitro, an MTT assay demonstrated that ISMN had a synergistic effect on the growth inhibitory effects of aspirin on HCT116 and SW620 colon cancer cells, while the growth of EA.hy926 normal endothelial cells was unaffected. This synergistic anti‑tumor effect was further validated in vivo using nude mouse HCT116 cell xenograft model. Observation of nuclear morphology, Annexin V-fluorescein isothiocyanate/propidium iodide double staining and a caspase-3 activity assay suggested that the combination of the two drugs induced apoptosis in HCT116 cells. Furthermore, the molecular mechanisms of the apoptotic effect of the drugs was assessed using an NO release assay, reverse transcription quantitative polymerase chain reaction analysis, western blot analysis and a luciferase reporter assay. It was certified that the increase in the amount of NO release, the decrease in the luciferase promoter activity and the expression of cyclin D1 and c-myc in HCT116 cells were affected by aspirin and ISMN in a synergistic manner. In conclusion, the present study was the first, to the best of our knowledge, to report on the synergistic apoptosis-inducing effects of aspirin and ISMN in human colon cancer cells, which were mediated via Wnt and NO signaling pathways. The results of the present study will facilitate the development of future therapeutic strategies.