Epithelial Galectin-3 Induced the Mitochondrial Complex Inhibition and Cell Cycle Arrest of CD8+ T Cells in Severe/Critical COVID-19.

Previous research suggested that the dramatical decrease in CD8+ T cells is a contributing factor in the poor prognosis and disease progression of COVID-19 patients. However, the underlying mechanisms are not fully understood. In this study, we conducted Single-cell RNA sequencing (scRNA-seq) and single-cell T cell receptor sequencing (scTCR-seq) analysis, which revealed a proliferative-exhausted MCM+FASLGlow CD8+ T cell phenotype in severe/critical COVID-19 patients. These CD8+ T cells were characterized by G2/M cell cycle arrest, downregulation of respiratory chain complex genes, and inhibition of mitochondrial biogenesis. CellChat analysis of infected lung epithelial cells and CD8+ T cells found that the galectin signaling pathway played a crucial role in CD8+ T cell reduction and dysfunction. To further elucidate the mechanisms, we established SARS-CoV-2 ORF3a-transfected A549 cells, and co-cultured them with CD8+ T cells for ex vivo experiments. Our results showed that epithelial galectin-3 inhibited the transcription of the mitochondrial respiratory chain complex III/IV genes of CD8+ T cells by suppressing the nuclear translocation of nuclear respiratory factor 1 (NRF1). Further findings showed that the suppression of NRF1 translocation was associated with ERK-related and Akt-related signaling pathways. Importantly, the galectin-3 inhibitor, TD-139, promoted nuclear translocation of NRF1, thus enhancing the expression of the mitochondrial respiratory chain complex III/IV genes and the mitochondrial biogenesis of CD8+ T cells. Our study provided new insights into the immunopathogenesis of COVID-19 and identified potential therapeutic targets for the prevention and treatment of severe/critical COVID-19 patients.

HBx promotes hepatocellular carcinoma progression by repressing the transcription level of miR-187-5p.

HBV-associated hepatitis B virus x protein (HBx) plays multiple roles in the development of hepatocellular carcinoma. In our prior study, we discovered that miR-187-5p expression was inhibited by HBx. To investigate the underlying molecular mechanism of HBx-mediated miR-187-5p downregulation in hepatocellular carcinoma cells, effects of HBx and miR-187-5p on hepatoma carcinoma cell were observed, as well as their interactions. Through in vitro and in vivo experiments, we demonstrated that overexpression of miR-187-5p inhibited proliferation, migration, and invasion. Simultaneously, we observed a dysregulation in the expression of miR-187-5p in liver cancer cell lines, which may be attributed to transcriptional inhibition through the E2F1/FoxP3 axis. Additionally, we noted that HBx protein is capable of enhancing the expression of E2F1, a transcription factor that promotes the expression of FoxP3. In conclusion, our results suggest that the inhibitory effect of HBx on miR-187-5p is mediated through the E2F1/FoxP3 axis. As shown in this work, HBx promotes hepatoma carcinoma cell proliferation, migration, and invasion through the E2F1/FoxP3/miR-187 axis. It provides a theoretical basis for finding therapeutic targets that will help clinic treatment for HCC.

NUF2 Promotes Breast Cancer Development as a New Tumor Stem Cell Indicator.

Multiple new subtypes of breast cancer (BRCA) are identified in women each year, rendering BRCA the most common and rapidly expanding form of cancer in females globally. NUF2 has been identified as a prognostic factor in various human cancers, regulating cell apoptosis and proliferation. However, its role in BRCA prognosis has not been clarified. This study explored the role of NUF2 in breast cancer development and prognosis using informatic analysis combined with in vivo intracellular studies. Through the online website TIMER, we evaluated the transcription profile of NUF2 across a variety of different cancer types and found that NUF2 mRNA was highly expressed in BRCA patients. Its transcription level was found to be related to the subtype, pathological stage, and prognosis of BRCA. The R program analysis showed a correlation of NUF2 with cell proliferation and tumor stemness in the BRCA patient samples. Subsequently, the association between the NUF2 expression level and immune cell infiltration was analyzed using the XIANTAO and TIMER tools. The results revealed that NUF2 expression was correlated with the responses of multiple immune cells. Furthermore, we observed the effect of NUF2 expression on tumor stemness in BRCA cell lines in vivo. The experimental results illuminated that the overexpression of NUF2 statistically upregulated the proliferation and tumor stemness ability of the BRCA cell lines MCF-7 and Hs-578T. Meanwhile, the knockdown of NUF2 inhibited the abilities of both cell lines, a finding which was verified by analyzing the subcutaneous tumorigenic ability in nude mice. In summary, this study suggests that NUF2 may play a key role in the development and progression of BRCA by affecting tumor stemness. As a stemness indicator, it has the potential to be one of the markers for the diagnosis of BRCA.

Dynamic Expression of EpCAM in Primary and Metastatic Lung Cancer Is Controlled by Both Genetic and Epigenetic Mechanisms.

Although great progress has been achieved in cancer treatment in the past decades, lung cancer remains the leading cause of cancer death, which is partially caused by the fact that most lung cancers are diagnosed at advanced stages. To improve the sensitivity and specificity of lung cancer diagnosis, the underlying mechanisms of current diagnosis methods are in urgent need to be explored. Herein, we find that the expression of EpCAM, the widely used molecular marker for tumor cell characterization and isolation, is strongly upregulated in primary lung tumors, which is caused by both gene amplification and promoter hypomethylation. In contrast, EpCAM expression is severely repressed in metastatic lung tumors, which can be reversed by epigenetic drugs, DNMT inhibitor 5-aza-dC and HDAC inhibitor MS-275. Moreover, tumor-associated macrophages (TAMs) impede EpCAM expression probably through TGFß-induced EMT signaling. These findings unveil the dynamic expression patterns of EpCAM and differential roles of epigenetic modification in EpCAM expression in primary and metastatic lung tumors, providing novel insights into tumor cell isolation and lung cancer diagnosis.

The third-generation anti-CD30 CAR T-cells specifically homing to the tumor and mediating powerful antitumor activity.

CAR T-cell therapy is well tolerated and effective in patients with Hodgkin lymphoma (HL) and anaplastic large cell lymphoma (ALCL). However, even second- generation anti-CD30 CAR T-cells with CD28 (28z) costimulatory domains failed to achieve the desired rate of complete responses. In the present study, we developed second-generation (CD28z) and third-generation (CD28BBz) CAR T-cells targeting CD30 and investigated their efficacy in vitro and in vivo. Both of CD28z and CD28BBz anti-CD30 CAR T cells were similar regarding amplification, T cell subsets distribution, T cell activity, effector/memory and exhaustion. However, we found that the 28BBz anti-CD30 CAR T-cells persist long-term, specifically homing to the tumor and mediating powerful antitumor activity in tumor xenograft models. Subsequently, we also demonstrated that the third generation anti-CD30 CAR T-cells have miner side effects or potential risks of tumorigenesis. Thus, anti-CD30 CAR T-cells represent a safe and effective treatment for Hodgkin lymphoma.

The metabolic and immunological characteristics of pregnant women with COVID-19 and their neonates.

Our aim was to investigate whether SARS-CoV-2 infection raised high risks of late pregnancy complications, and posed health problems in fetuses and neonates. We analyzed the data of COVID-19 pregnant women with COVID-19 during late pregnancy and their neonates. Eleven out of 16 (69%) pregnant women with COVID-19 had ++ or +++ of ketone body in urine. The blood uric acid of pregnant patients was 334 µmol/L (IQR, 269-452). D-dimer and FDP in pregnant patients were 3.32 mg/L (IQR, 2.18-4.21) and 9.6 mg/L (IQR, 5.9-12.4). Results of blood samples collected at birth showed that 16 neonates had leukocytes (15.7 × 109/L (IQR, 13.7-17.2)), neutrophils (11.1 × 109/L (IQR, 9.2-13.2)), CK (401 U/L (IQR, 382-647)), and LDH (445 U/L (IQR, 417-559)). Twenty-four hours after birth, a neonate from COVID-19 woman had fever and positive of SARS-CoV-2 gene. Another woman had strongly positive for SARS-CoV-2 gene (+++) for 4 weeks, and delivered one neonate who had SARS-CoV-2 IgM (46 AU/mL) and IgG (140 AU/mL) on day 1 after birth. In the third trimester, COVID-19 infection in pregnant patients raised high risks of ketonuria, hypercoagulable state, and hyperfibrinolysis, which may lead to severe complications. COVID-19 increased the inflammatory responses of placenta, and fetuses and neonates had potential organ dysregulation and coagulation disorders. There was a potential intrauterine transmission while pregnant women had high titer of SARS-CoV-2, but it is necessary to detect SARS-CoV-2 in the blood cord, placenta, and amniotic fluid to further confirm intrauterine infection of fetuses.

The Metabolic Changes and Immune Profiles in Patients With COVID-19.

To explore the metabolic changes and immune profiles in patients with COVID-19, we analyzed the data of patients with mild and severe COVID-19 as well as young children with COVID-19. Of the leukocytes, 47% (IQR, 33-59) were lymphocytes [2.5 × 109/L (IQR, 2.2-3.3)], and monocytes were 0.51 × 109/L (IQR, 0.45-0.57) in young children with COVID-19. In 32 mild COVID-19 patients, circulating monocytes were 0.45 × 109/L (IQR, 0.36-0.64). Twenty-one severe patients had low PO2 [57 mmHg (IQR, 50-73)] and SO2 [90% (IQR, 86-93)] and high lactate dehydrogenase [580 U/L (IQR, 447-696)], cardiac troponin I [0.07 ng/mL (IQR, 0.02-0.30)], and pro-BNP [498 pg/mL (IQR, 241-1,726)]. Serum D-dimer and FDP were 9.89 mg/L (IQR, 3.62-22.85) and 32.7 mg/L (IQR, 12.8-81.9), and a large number of RBC (46/µL (IQR, 4-242) was presented in urine, a cue of disseminated intravascular coagulation (DIC) in severe patients. Three patients had comorbidity with diabetes, and 18 patients without diabetes also presented high blood glucose [7.4 mmol/L (IQR, 5.9-10.1)]. Fifteen of 21 (71%) severe cases had urine glucose +, and nine of 21 (43%) had urine ketone body +. The increased glucose was partially caused by reduced glucose consumption of cells. Severe cases had extraordinarily low serum uric acid [176 µmol/L (IQR, 131-256)]. In the late stage of COVID-19, severe cases had extremely low CD4+ T cells and CD8+ T cells, but unusually high neutrophils [6.5 × 109/L (IQR, 4.8-9.6)], procalcitonin [0.27 ng/mL (IQR, 0.14-1.94)], C-reactive protein [66 mg/L (IQR, 25-114)] and an extremely high level of interleukin-6. Four of 21 (19%) severe cases had co-infection with fungi, and two of 21 (9%) severe cases had bacterial infection. Our findings suggest that, severe cases had acute respiratory distress syndrome (ARDS) I-III, and metabolic disorders of glucose, lipid, uric acid, etc., even multiple organ dysfunction (MODS) and DIC. Increased neutrophils and severe inflammatory responses were involved in ARDS, MODS, and DIC. With the dramatical decrease of T-lymphocytes, severe cases were susceptible to co-infect with bacteria and fungi in the late stage of COVID-19. In young children, extremely high lymphocytes and monocytes might be associated with the low morbidity of COVID-19. The significantly increased monocytes might play an important role in the recovery of patients with mild COVID-19.

Causative role of PDLIM2 epigenetic repression in lung cancer and therapeutic resistance.

Most cancers are resistant to anti-PD-1/PD-L1 and chemotherapy. Herein we identify PDLIM2 as a tumor suppressor particularly important for lung cancer therapeutic responses. While PDLIM2 is epigenetically repressed in human lung cancer, associating with therapeutic resistance and poor prognosis, its global or lung epithelial-specific deletion in mice causes increased lung cancer development, chemoresistance, and complete resistance to anti-PD-1 and epigenetic drugs. PDLIM2 epigenetic restoration or ectopic expression shows antitumor activity, and synergizes with anti-PD-1, notably, with chemotherapy for complete remission of most lung cancers. Mechanistically, through repressing NF-κB/RelA and STAT3, PDLIM2 increases expression of genes involved in antigen presentation and T-cell activation while repressing multidrug resistance genes and cancer-related genes, thereby rendering cancer cells vulnerable to immune attacks and therapies. We identify PDLIM2-independent PD-L1 induction by chemotherapeutic and epigenetic drugs as another mechanism for their synergy with anti-PD-1. These findings establish a rationale to use combination therapies for cancer treatment.

NF-κB RelA renders tumor-associated macrophages resistant to and capable of directly suppressing CD8+ T cells for tumor promotion.

Activation of the inflammatory transcription factor NF-κB in tumor-associated macrophages (TAMs) is assumed to contribute to tumor promotion. However, whether and how NF-κB drives the antitumor macrophages to become pro-tumorigenic have not been determined in any cancer type yet. Similarly, how TAMs repress CD8+ cytotoxic T lymphocytes (CTLs) remains largely unknown, although their importance in regulatory T (Treg) cell regulation and tumor promotion has been well appreciated. Here, using an endogenous lung cancer model we uncover a direct crosstalk between TAMs and CTLs. TAMs suppress CTLs through the T-cell inhibitory molecule B7x (B7-H4/B7S1) in a cell-cell contact manner, whereas CTLs kill TAMs in a tumor antigen-specific manner. Remarkably, TAMs secrete the known T-cell suppressive cytokine interleukin-10 (IL-10) to activate, but not to repress, CTLs. Notably, one major role of cell-intrinsic NF-κB RelA is to drive TAMs to suppress CTLs for tumor promotion. It induces B7x expression in TAMs directly, and restricts IL-10 expression indirectly by repressing expression of the NF-κB cofactor Bcl3 and subsequent Bcl3/NF-κB1-mediated transcription of IL-10. It also renders TAMs resistant to CTLs by up-regulating anti-apoptotic genes. These studies help understand how immunity is shaped in lung tumorigenesis, and suggest a RelA-targeted immunotherapy for this deadliest cancer.

Platelet HMGB1 is required for efficient bacterial clearance in intra-abdominal bacterial sepsis in mice.

Thrombocytopenia impairs host defense and hemostasis in sepsis. However, the mechanisms of how platelets regulate host defense are not fully understood. High-mobility group box 1 (HMGB1), a danger-associated molecular pattern protein, is released during infection and contributes to the pathogenesis of sepsis. Platelets express HMGB1, which is released on activation and has been shown to play a critical role in thrombosis, monocyte recruitment, and neutrophil extracellular trap (NET) production. However, the contribution of platelet HMGB1 to host defense is unknown. To determine the role of platelet HMGB1 in polymicrobial sepsis, platelet-specific HMGB1 knockout (HMGB1 platelet factor 4 [PF4]) mice were generated and were subjected to cecal ligation and puncture (CLP), a clinically relevant intra-abdominal sepsis model. Compared with HMGB1 Flox mice and wild-type (WT) mice, HMGB1 PF4 mice showed significantly higher bacterial loads in the peritoneum and blood, an exaggerated systemic inflammation response, and significantly greater mortality after CLP. Deletion of HMGB1 in platelets was associated with lower platelet-derived chemokines (PF4 and RANTES) in the peritoneal cavity, and a decrease of platelet-neutrophil interaction in the lung after CLP. In vitro, neutrophils cocultured with activated HMGB1 knockout platelets showed fewer platelet-neutrophil aggregates, reduced reactive oxygen species (ROS) burst as compared with control. Taken together, these data reveal an unrecognized role of platelet HMGB1 in the regulation of neutrophil recruitment and activation via modulation of platelet activation during sepsis.

Myeloid STAT3 Promotes Lung Tumorigenesis by Transforming Tumor Immunosurveillance into Tumor-Promoting Inflammation.

One of the most fundamental and challenging questions in the cancer field is how immunity in patients with cancer is transformed from tumor immunosurveillance to tumor-promoting inflammation. Here, we identify the transcription factor STAT3 as the culprit responsible for this pathogenic event in lung cancer development. We found that antitumor type 1 CD4+ T-helper (Th1) cells and CD8+ T cells were directly counter balanced in lung cancer development with tumor-promoting myeloid-derived suppressor cells (MDSCs) and suppressive macrophages, and that activation of STAT3 in MDSCs and macrophages promoted tumorigenesis through pulmonary recruitment and increased resistance of suppressive cells to CD8+ T cells, enhancement of cytotoxicity toward CD4+ and CD8+ T cells, induction of regulatory T cell (Treg), inhibition of dendritic cells (DC), and polarization of macrophages toward the M2 phenotype. The deletion of myeloid STAT3 boosted antitumor immunity and suppressed lung tumorigenesis. These findings increase our understanding of immune programming in lung tumorigenesis and provide a mechanistic basis for developing STAT3-based immunotherapy against this and other solid tumors. Cancer Immunol Res; 5(3); 257-68. ©2017 AACR.

Interleukin-6 Prevents the Initiation but Enhances the Progression of Lung Cancer.

Recent studies suggest that high expression of the proinflammatory cytokine IL6 is associated with poor survival of lung cancer patients. Accordingly, IL6 has been a target of great interest for lung cancer therapy. However, the role of IL6 in lung cancer has not been determined yet. Here, we demonstrate that IL6 plays opposite roles in the initiation and growth of lung cancer in a mouse model of lung cancer induced by the K-Ras oncogene. We find that compared with wild-type mice, IL6-deficient mice developed much more lung tumors after an activating mutant of K-Ras was induced in the lungs. However, lung tumors developed in IL6-deficient mice were significantly smaller. Notably, both the lung tumor-suppressing and -promoting functions of IL6 involve its ability in activating the transcription factor STAT3. IL6/STAT3 signaling suppressed lung cancer initiation through maintaining lung homeostasis, regulating lung macrophages, and activating cytotoxic CD8 T cells under K-Ras oncogenic stress, whereas it promoted lung cancer cell growth through inducing the cell proliferation regulator cyclin D1. These studies reveal a previously unexplored role of IL6/STAT3 signaling in maintaining lung homeostasis and suppressing lung cancer induction. These studies also significantly improve our understanding of lung cancer and provide a molecular basis for designing IL6/STAT3-targeted therapies for this deadliest human cancer.

Differential roles of STAT3 in the initiation and growth of lung cancer.

Signal transducer and activator of transcription 3 (STAT3) is linked to multiple cancers, including pulmonary adenocarcinoma. However, the role of STAT3 in lung cancer pathogenesis has not been determined. Using lung epithelial-specific inducible knockout strategies, we demonstrate that STAT3 has contrasting roles in the initiation and growth of both chemically and genetically induced lung cancers. Selective deletion of lung epithelial STAT3 in mice before cancer induction by the smoke carcinogen, urethane, resulted in increased lung tissue damage and inflammation, K-Ras oncogenic mutations and tumorigenesis. Deletion of lung epithelial STAT3 after establishment of lung cancer inhibited cancer cell proliferation. Simultaneous deletion of STAT3 and expression of oncogenic K-Ras in mouse lung elevated pulmonary injury, inflammation and tumorigenesis, but reduced tumor growth. These studies indicate that STAT3 prevents lung cancer initiation by maintaining pulmonary homeostasis under oncogenic stress, whereas it facilitates lung cancer progression by promoting cancer cell growth. These studies also provide a mechanistic basis for targeting STAT3 to lung cancer therapy.

PDLIM2 restricts Th1 and Th17 differentiation and prevents autoimmune disease.

BACKGROUND: PDLIM2 is essential for the termination of the inflammatory transcription factors NF-κB and STAT but is dispensable for the development of immune cells and immune tissues/organs. Currently, it remains unknown whether and how PDLIM2 is involved in physiologic and pathogenic processes. RESULTS: Here we report that naive PDLIM2 deficient CD4+ T cells were prone to differentiate into Th1 and Th17 cells. PDLIM2 deficiency, however, had no obvious effect on lineage commitment towards Th2 or Treg cells. Notably, PDLIM2 deficient mice exhibited increased susceptibility to experimental autoimmune encephalitis (EAE), a Th1 and/or Th17 cell-mediated inflammatory disease model of multiple sclerosis (MS). Mechanistic studies further indicate that PDLIM2 was required for restricting expression of Th1 and Th17 cytokines, which was in accordance with the role of PDLIM2 in the termination of NF-κB and STAT activation. CONCLUSION: These findings suggest that PDLIM2 is a key modulator of T-cell-mediated immune responses that may be targeted for the therapy of human autoimmune diseases.

Infection and replication of avian influenza H5N1 virus in an infected human.

The highly pathogenic avian influenza H5N1 viruses usually cause severe diseases and high mortality in infected humans. However, the tissue tropism and underlying pathogenesis of H5N1 virus infection in humans have not been clearly elucidated yet. In this study, an autopsy was conducted to better understand H5N1 virus distributions in tissues of infected humans, and whether H5N1 virus can replicate in extrapulmonary tissues. We found that the lungs had the higher viral load than the spleen, whereas no detectable viruses in tissues of heart, liver, kidney, large intestine, small intestine, or brain. Specifically, the viral load was higher in the left lung (7.1 log10 copies per ml) in relation to the right lung (5.7 log10 copies per ml), resulting in more severe pathological damage in the left lung, and lung tissues contained both positive- and negative-stranded viral RNA. However, there existed a low level of H5N1 viruses in the spleen (3.8 log10 copies per ml), with the absence of positive-stranded viral RNA. Our results indicate that replication of H5N1 viruses mainly occurs in the lungs, and the degree of lung damage is highly correlated with the viral load in the lungs. The low-load viruses in the spleen might be introduced through blood circulation or other ways.

Genomic analysis of a Chinese isolate of Getah-like virus and its phylogenetic relationship with other Alphaviruses.

An alphavirus, M-1 strain, was isolated from a pool of culicine mosquitoes collected in Hainan island of China during an arbovirus survey in 1964. In the present study, we determined the complete nucleotide sequence of the M-1 strain using RT-PCR and RACE techniques. The M-1 genome is 11,690 nucleotides (nt) in length and contains two open reading frames (ORFs) encoding four nonstructural proteins and five structural proteins, respectively. Searches using Blast and comparison analyses suggested that M-1 is closely linked to Sagiyama virus (SAGV, AB032553) with 98% identity and Getah viruse (GETV, AY702913) with 97.8% identity in the full-length nucleotide sequence. However, compared with SAGV, there is 1 deletion (3 nucleotides in length) in the Capsid region, a deletion in the 3' untranslated region (10 nucleotides in length) and 2 insertions in the 3' untranslated region involving a total of 5 nucleotides. Interestingly, from the 5' UTR to the end of coding region, M-1 share the highest identity with GETV, even though the identity of 3' UTR drops dramatically to 76.2%. Furthermore, phylogenetic analysis based on the complete genomic sequences and sequences for structural or non-structural proteins of M-1 and 15 alphaviruses showed that M-1 grouped with GETV first and then grouped together with SAGV. Based on the comparison analysis and phylogenetic analysis, we conclude that M-1 strain can be considered as a strain that is a Chinese isolate of Getah-like virus.

Selection of SARS-coronavirus-specific B cell epitopes by phage peptide library screening and evaluation of the immunological effect of epitope-based peptides on mice.

Antibodies to SARS-Coronavirus (SARS-CoV)-specific B cell epitopes might recognize the pathogen and interrupt its adherence to and penetration of host cells. Hence, these epitopes could be useful for diagnosis and as vaccine constituents. Using the phage-displayed peptide library screening method and purified Fab fragments of immunoglobulin G (IgG Fab) from normal human sera and convalescent sera from SARS-CoV-infected patients as targets, 11 B cell epitopes of SARS-CoV spike glycoprotein (S protein) and membrane protein (M protein) were screened. After a bioinformatics tool was used to analyze these epitopes, four epitope-based S protein dodecapeptides corresponding to the predominant epitopes were chosen for synthesis. Their antigenic specificities and immunogenicities were studied in vitro and in vivo. Flow cytometry and ELISPOT analysis of lymphocytes as well as a serologic analysis of antibody showed that these peptides could trigger a rapid, highly effective, and relatively safe immune response in BALB/c mice. These findings might aid development of SARS diagnostics and vaccines. Moreover, the role of S and M proteins as important surface antigens is confirmed.

Secreted expression and purification of dengue 2 virus full-length nonstructural glycoprotein NS1 in Pichia pastoris.

The dengue 2 virus (DEN-2) RNA (NGC strain) was used as a substrate to produce DNA clones of the full-length NS1 genes via reverse transcriptase synthesis of cDNA followed by polymerase chain reaction amplification of the NS1 region. Products were cloned into pPICZalphaB vector for sequencing and into Pichia pastoris for expression. A recombinant protein with a molecular size of approximately 80 KDa was secreted into the supernatant from the yeast cells when induced with methanol. The expressed protein was able to bind with mouse polyclonal antibody or NS1-specific monoclonal antibody of dengue 2 virus. Purified NS1-poly(His)-tagged fusion protein was obtained from the expressed product by passing through a metal-chelating affinity chromatographic (MCAC) column. The study also verified that our purified rNS1 protein retained its antigenicity. High-level production of the rNS1 protein up to 70 mg/l indicates that P. pastoris is an efficient expression system for dengue virus full-length NS1 glycoprotein.