Studying tourism development and its impact on carbon emissions.

Analyzing the influence of tourism on carbon emission has significant implications for promoting the sustainable development of tourism. Based on the panel data of 31 tourist cities in China from 2005 to 2022, this study utilizes a structural equation model to explore the carbon reduction effect of tourism development and its influencing mechanism. The results show that: (1) The overall carbon emission efficiency of tourism cities first decreased and then increased, rised to a peak of 0.923 in 2022. (2) Tourism development has a significant positive impact on carbon emission efficiency, and there are three influence paths: tourism → environmental regulation → carbon emission efficiency, tourism → environmental regulation → industrial structure → carbon emission efficiency, and tourism → industrial structure → carbon emission efficiency. (3) The influence of tourism development on carbon emission efficiency mainly depends on the direct effect, and the development of tourism also indirectly affect the industrial structure. Environmental regulation also mainly depends on the direct effect on carbon emission efficiency. (4) Foreign direct investment lead to the reduction of carbon emission efficiency in both direct and indirect aspects.

Spatial and temporal evolution of urban carbon emission efficiency in China.

Improving carbon emission efficiency is crucial for achieving carbon peak and carbon neutrality. This paper analyzes the carbon emission efficiency of Chinese cities using panel data from 275 prefecture-level cities between 2006 and 2020. The super-efficiency SBM (undesirable slacks-based measurement) model of undesired output, combined with kernel density estimation and exploratory data analysis, is employed. This study finds, firstly, from 2006 to 2020, the average efficiency of carbon emissions in Chinese cities declined from 0.53 to 0.48, indicating a downward trend. Secondly, from a temporal perspective, the level of dispersion in urban carbon emission efficiency has become increasingly distinct over time, coupled with a decrease in polarization. Thirdly, in terms of spatial analysis, urban carbon emission efficiency in China shows a positive correlation in a global context. In terms of local spatial correlation, it primarily exhibits high-high and low-low clusters, with a few instances of low-high and high-low clusters. Finally, based on the research findings, this paper proposes suggestions to improve urban carbon emission efficiency.

Correction: Detection of airborne pathogens with single photon counting and a real-time spectrometer on microfluidics.

Correction for 'Detection of airborne pathogens with single photon counting and a real-time spectrometer on microfluidics' by Ning Yang et al., Lab Chip, 2022, https://doi.org/10.1039/D2LC00934J.

Assessment of sulfamethoxazole toxicity to marine mussels (Mytilus galloprovincialis): Combine p38-MAPK signaling pathway modulation with histopathological alterations.

Sulfamethoxazole (SMX), is a ubiquitous antibiotic in the aquatic environment and received concerns on its health hazards, especially its sub-lethal effects on non-target organisms which were remained largely unknown. In the present study, in order to investigate SMX induced tissue damages and reveal underlying mechanisms, marine mussels, Mytilus galloprovincialis were challenged to SMX series (0.5, 50 and 500 µg/L) for six-days followed by six-day-recovery. Comprehensive histopathological alteration (including qualitative, semi-quantitative and quantitative indices), together with transcriptional and (post-) translational responses of key factors (p38, NFκB and p53) in the p38-MAPK signaling pathway were analyzed in gills and digestive glands. Tissue-specific responses were clearly investigated with gills showing more prompt responses and digestive glands showing higher tolerance to SMX. The histopathology showed that SMX triggered inflammatory damages in both tissues and quantitative analysis revealed more significant responses, suggesting its potential as a valuable health indicator. SMX activated expressions of p38, NFκB and p53 at transcriptional and (post-) translational levels, especially after exposed to low level SMX, evidenced by p38 coupled with NFκB/p53 regulation on immunity defense in mussels. Less induction of targeted molecules under severe SMX exposure indicated such signaling transduction may not be efficient enough and can result in inflammatory damages. Taken together, this study expanded the understanding of aquatic SMX induced health risk in marine mussels and the underlying regulation mechanism through p38 signaling transduction.

Detection of airborne pathogens with single photon counting and a real-time spectrometer on microfluidics.

The common practice for monitoring pathogenic bioaerosols is to collect bioaerosols from air and then detect them, which lacks timeliness and accuracy. In order to improve the detection speed, here we demonstrate an innovative airflow-based optical detection method for directly identifying aerosol pathogens, and built a microfluidic-based counter composite spectrometer detection platform, which simplifies sample preparation and collection detection from two steps to one step. The method is based on principal component analysis and partial least squares discriminant analysis for particle species identification and dynamic transmission spectroscopy analysis, and single-photon measurement is used for particle counting. Compared with traditional microscopic counting and identification methods, the particle counting accuracy is high, the standard deviation is small, and the counting accuracy exceeds 92.2%. The setup of dynamic transmission spectroscopy analysis provides high-precision real-time particle identification with an accuracy rate of 93.75%. As the system is further refined, we also foresee potential applications of this method in agricultural disease control, environmental control, and infectious disease control in aerosol pathogen detection.

SARS-CoV-2 Nsp14 protein associates with IMPDH2 and activates NF-κB signaling.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection leads to NF-κB activation and induction of pro-inflammatory cytokines, though the underlying mechanism for this activation is not fully understood. Our results reveal that the SARS-CoV-2 Nsp14 protein contributes to the viral activation of NF-κB signaling. Nsp14 caused the nuclear translocation of NF-κB p65. Nsp14 induced the upregulation of IL-6 and IL-8, which also occurred in SARS-CoV-2 infected cells. IL-8 upregulation was further confirmed in lung tissue samples from COVID-19 patients. A previous proteomic screen identified the putative interaction of Nsp14 with host Inosine-5'-monophosphate dehydrogenase 2 (IMPDH2), which is known to regulate NF-κB signaling. We confirmed the Nsp14-IMPDH2 protein interaction and identified that IMPDH2 knockdown or chemical inhibition using ribavirin (RIB) and mycophenolic acid (MPA) abolishes Nsp14- mediated NF-κB activation and cytokine induction. Furthermore, IMPDH2 inhibitors (RIB, MPA) or NF-κB inhibitors (bortezomib, BAY 11-7082) restricted SARS-CoV-2 infection, indicating that IMPDH2-mediated activation of NF-κB signaling is beneficial to viral replication. Overall, our results identify a novel role of SARS-CoV-2 Nsp14 in inducing NF-κB activation through IMPDH2 to promote viral infection.

FACT subunit SUPT16H associates with BRD4 and contributes to silencing of interferon signaling.

FACT (FAcilitates Chromatin Transcription) is a heterodimeric protein complex composed of SUPT16H and SSRP1, and a histone chaperone participating in chromatin remodeling during gene transcription. FACT complex is profoundly regulated, and contributes to both gene activation and suppression. Here we reported that SUPT16H, a subunit of FACT, is acetylated in both epithelial and natural killer (NK) cells. The histone acetyltransferase TIP60 contributes to the acetylation of SUPT16H middle domain (MD) at lysine 674 (K674). Such acetylation of SUPT16H is recognized by bromodomain protein BRD4, which promotes protein stability of SUPT16H in both epithelial and NK cells. We further demonstrated that SUPT16H-BRD4 associates with histone modification enzymes (HDAC1, EZH2), and further regulates their activation status and/or promoter association as well as affects the relevant histone marks (H3ac, H3K9me3 and H3K27me3). BRD4 is known to profoundly regulate interferon (IFN) signaling, while such function of SUPT16H has never been explored. Surprisingly, our results revealed that SUPT16H genetic knockdown via RNAi or pharmacological inhibition by using its inhibitor, curaxin 137 (CBL0137), results in the induction of IFNs and interferon-stimulated genes (ISGs). Through this mechanism, depletion or inhibition of SUPT16H is shown to efficiently inhibit infection of multiple viruses, including Zika, influenza, and SARS-CoV-2. Furthermore, we demonstrated that depletion or inhibition of SUPT16H also causes the remarkable activation of IFN signaling in NK cells, which promotes the NK-mediated killing of virus-infected cells in a co-culture system using human primary NK cells. Overall, our studies unraveled the previously un-appreciated role of FACT complex in coordinating with BRD4 and regulating IFN signaling in both epithelial and NK cells, and also proposed the novel application of the FACT inhibitor CBL0137 to treat viral infections.

CircRFWD3 promotes HNSCC metastasis by modulating miR-27a/b/PPARγ signaling.

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer in the world, the 5-year survival rate of patients with HNSCC is still about 50% due to frequent metastasis and recurrence. Circular RNAs (circRNAs) have been characterized as key regulators of gene expression in numerous malignancies. However, the role of circRNA in HNSCC metastasis remains largely unknown. Here, we demonstrated that the circRFWD3 was significantly upregulated in HNSCC tissues and cell lines by circRNA microarray analysis and qPCR. Notably, high expression of circRFWD3 is related to highly aggressive HNSCC cell lines and lymph node metastasis in HNSCC patients. After that, Sanger sequencing, RNase R, and actinomycin D assay were performed to verify the ring structure of circRFWD3. Then functional experiments found it could promote the metastasis of HNSCC cells both in vitro and in vivo. Mechanistically, a dual-luciferase reporter assay, FISH, RIP, RNA pull-down, RNA-seq, and western blot experiments were employed and found that circRFWD3 served as a miRNAs sponge for miR-27a/27b, leading to the upregulation of PPARγ, and then promoted HNSCC metastasis via NF-κB/MMP13 pathway. Finally, ISH and IHC were carried out to determine the expression levels and clinical significances of circRFWD3 and PPARγ in clinical cohorts of HNSCC. According to the analysis results from two independent HNSCC cohorts, upregulated expression of circRFWD3 and PPARγ were positively associated with worse survival in patients with HNSCC. Overall, our results uncover that circRFWD3 acts a critical role in promoting the aggressiveness of HNSCC cells and is a prognostic marker for the disease, indicating that circRFWD3 may act as a potential therapeutic target in HNSCC.

Tanzawaic Acids from a Deep-Sea Derived Penicillium Species.

Twelve new tanzawaic acid derivatives, penitanzacids A-F (1-6), and G-J (9-12), and hatsusamides C-D (13-14), together with two revised structures [tanzawaic acids I-J (7-8)] and three known compounds (15-17) were isolated from the deep-sea-derived fungus Penicillium sp. KWF32. Their structures including absolute configurations were elucidated by spectroscopic data analysis, HRESIMS data, modified Mosher's method, chemical degradation studies, ECD calculations, single crystal X-ray diffraction, and biogenic considerations in comparison with reported known analogues. Penitanzacids H-J (10-12) represent the first examples of this family with a C3 side chain and support the proposed biosynthetic pathway in which the side chain is connected to the decalin backbone. Hatsusamides C-D (13-14) have a hybrid skeleton formed by linking a tanzawaic acid and a diketopiperazine through an ester bond. Compounds 13 and 14 exhibit weak cytotoxicity against the A549 cell line.

Polyamine biosynthesis and eIF5A hypusination are modulated by the DNA tumor virus KSHV and promote KSHV viral infection.

Polyamines are critical metabolites involved in various cellular processes and often dysregulated in cancers. Kaposi's sarcoma-associated Herpesvirus (KSHV), a defined human oncogenic virus, leads to profound alterations of host metabolic landscape to favor development of KSHV-associated malignancies. In our studies, we identified that polyamine biosynthesis and eIF5A hypusination are dynamically regulated by KSHV infection through modulation of key enzymes (ODC1 and DHPS) of these pathways. During KSHV latency, ODC1 and DHPS are upregulated along with increase of hypusinated eIF5A (hyp-eIF5A), while hyp-eIF5A is further induced along with reduction of ODC1 and intracellular polyamines during KSHV lytic reactivation. In return these metabolic pathways are required for both KSHV lytic reactivation and de novo infection. Further analysis unraveled that synthesis of critical KSHV latent and lytic proteins (LANA, RTA) depends on hypusinated-eIF5A. We also demonstrated that KSHV infection can be efficiently and specifically suppressed by inhibitors targeting these pathways. Collectively, our results illustrated that the dynamic and profound interaction of a DNA tumor virus (KSHV) with host polyamine biosynthesis and eIF5A hypusination pathways promote viral propagation, thus defining new therapeutic targets to treat KSHV-associated malignancies.

Differential Expression of CREM/ICER Isoforms Is Associated with the Spontaneous Control of HIV Infection.

A rare subset of HIV-infected individuals, termed elite controllers (ECs), can maintain long-term control over HIV replication in the absence of antiretroviral therapy (ART). To elucidate the biological mechanism of resistance to HIV replication at the molecular and cellular levels, we performed RNA sequencing and identified alternative splicing variants from ECs, HIV-infected individuals undergoing ART, ART-naive HIV-infected individuals, and healthy controls. We identified differential gene expression patterns that are specific to ECs and may influence HIV resistance, including alternative RNA splicing and exon usage variants of the CREM/ICER gene (cyclic AMP [cAMP]-responsive element modulator/inducible cAMP early repressors). The knockout and knockdown of specific ICER exons that were found to be upregulated in ECs resulted in significantly increased HIV infection in a CD4+ T cell line and primary CD4+ T cells. Overexpression of ICER isoforms decreased HIV infection in primary CD4+ T cells. Furthermore, ICER regulated HIV long terminal repeat (LTR) promoter activity in a Tat-dependent manner. Together, these results suggest that ICER is an HIV host factor that may contribute to the HIV resistance of ECs. These findings will help elucidate the mechanisms of HIV control by ECs and may yield a new approach for treatment of HIV. IMPORTANCE A small group of HIV-infected individuals, termed elite controllers (ECs), display control of HIV replication in the absence of antiretroviral therapy (ART). However, the mechanism of ECs' resistance to HIV replication is not clear. In our work, we found an increased expression of specific, small isoforms of ICER in ECs. Further experiments proved that ICER is a robust host factor to regulate viral replication. Furthermore, we found that ICER regulates HIV LTR promoter activity in a Tat-dependent manner. These findings suggest that ICER is related to spontaneous control of HIV infection in ECs. This study may help elucidate a novel target for treatment of HIV.

Reverted HIV-1 Mutants in CD4+ T-Cells Reveal Critical Residues in the Polar Region of Viral Envelope Glycoprotein.

HIV-1 envelope glycoprotein (Env) interacts with cell surface receptors and induces membrane fusion to enter cells and initiate infection. HIV-1 Env on virions comprises trimers of the gp120 and gp41 subunits. The polar region (PR) in the N-terminus of gp41 is composed of 17 conserved residues, including seven polar amino acids. We have reported that the PR is crucial for Env trimer stability and fusogenicity. Mutations of three highly conserved residues (S534P, T536A, or T538A) in the PR of HIV-1NL4-3 significantly decrease or eliminate viral infectivity due to defective fusion and increased gp120 shedding. To identify compensatory Env mutations that restore viral infectivity, we infected a CD4+ T-cell line with PR mutants pseudotyped with wild-type (WT) HIV-1 Env or vesicular stomatitis virus envelope glycoprotein (VSV-G). We found that PR mutant-infected CD4+ T-cells produced infectious viruses at 7 days postinfection (dpi). Sequencing of the env cDNA from cells infected with the recovered HIV-1 revealed that the S534P mutant reverted to serine or threonine at residue 534. Interestingly, the combined PR-mutant HIV-1 (S534P/T536A or S534P/T536A/T538A) recovered its infectivity and reverted to S534, but maintained the T536A or T538A mutation, suggesting that HIV-1 replication in CD4+ T-cells can tolerate T536A and T538A Env mutations, but not S534P. Moreover, VSV-G-pseudotyped HIV-1 mutants with a fusion-defective Env also recovered infectivity in CD4+ T-cells through reverted Env mutations. These new observations help define the Env residues critical for HIV-1 infection and demonstrate that Env-defective HIV-1 mutants can rapidly regain replication competency in CD4+ T-cells. IMPORTANCE Our previous mutagenesis study revealed that serine at position 534 of HIV-1 Env is critical for viral infectivity. We found that HIV-1 Env containing serine to proline mutation at position 534 (S534P) are incapable of supporting virus-cell and cell-cell fusion. To investigate whether these mutant viruses can recover infectivity and what amino acid changes account for recovered infectivity, we infected CD4+ T-cells with Env-mutant HIV-1 pseudotyped with WT HIV-1 Env or VSV-G and monitored cultures for the production of infectious viruses. Our results showed that most of the pseudotyped viruses recovered their infectivity within 1-week postinfection, and all the recovered viruses mutated proline at position 534. These observations help define the Env residues critical for HIV-1 replication. Because Env-defective HIV-1 mutants can rapidly regain replication competency in CD4+ T-cells, it is important to carefully monitor viral mutations for biosafety consideration when using HIV-1-derived lentivirus vectors pseudotyped with Env.

SARS-CoV-2 Nsp14 activates NF-κB signaling and induces IL-8 upregulation.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection leads to NF-κB activation and induction of pro-inflammatory cytokines, though the underlying mechanism for this activation is not fully understood. Our results reveal that the SARS-CoV-2 Nsp14 protein contributes to the viral activation of NF-κB signaling. Nsp14 caused the nuclear translocation of NF-κB p65. Nsp14 induced the upregulation of IL-6 and IL-8, which also occurred in SARS-CoV-2 infected cells. IL-8 upregulation was further confirmed in lung tissue samples from COVID-19 patients. A previous proteomic screen identified the putative interaction of Nsp14 with host Inosine-5'-monophosphate dehydrogenase 2 (IMPDH2) protein, which is known to regulate NF-κB signaling. We confirmed the Nsp14-IMPDH2 protein interaction and found that IMPDH2 knockdown or chemical inhibition using ribavirin (RIB) and mycophenolic acid (MPA) abolishes Nsp14-mediated NF-κB activation and cytokine induction. Furthermore, IMDPH2 inhibitors (RIB, MPA) efficiently blocked SARS-CoV-2 infection, indicating that IMDPH2, and possibly NF-κB signaling, is beneficial to viral replication. Overall, our results identify a novel role of SARS-CoV-2 Nsp14 in causing the activation of NF-κB.

Sulfamethoxazole induced systematic and tissue-specific antioxidant defense in marine mussels (Mytilus galloprovincialis): Implication of antibiotic's ecotoxicity.

Sulfamethoxazole (SMX), recognized as emerging pollutant, has been frequently detected in aquatic environment. However, effects induced by SMX and the underneath mechanism on non-target aquatic organisms, marine mussels (Mytilus galloprovincialis), are still largely unknown. In present study, marine mussels were exposed to SMX (nominal concentrations 0.5, 50 and 500 µg/L) for 6 days, followed by 6 days depuration and responses of antioxidant defenses, e.g. superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST), etc., at transcriptional, translational and functional levels were evaluated in two vital tissues, gills and digestive glands. Results showed SMX can be accumulated in mussels while the bio-accumulative ability was low under the experimental condition. A systemic but not completely synchronous antioxidant defense at different levels upon SMX exposure. The transcriptional alteration was more sensitive and had the potential to be used as early warning of SMX induced ecotoxicity. Complementary function of antioxidant enzymes with specific alteration of metabolism related gene (gst) suggested that further researches should focused on SMX metabolism and SMX induced effects simultaneously. Significant tissue-specific antioxidant responses were discovered and gills showed earlier and quicker reacting ability than digestive glands, which was closely related to the functional diversity and different thresholds of xenobiotics allowance.

FACT subunit SUPT16H associates with BRD4 and contributes to silencing of antiviral interferon signaling.

FACT ( FA cilitates C hromatin T ranscription) is a heterodimeric protein complex composed of SUPT16H and SSRP1, and a histone chaperone participating in chromatin remodeling during gene transcription. FACT complex is profoundly regulated, and contributes to both gene activation and suppression. Here we reported that SUPT16H, a subunit of FACT, is acetylated at lysine 674 (K674) of middle domain (MD), which involves TIP60 histone acetyltransferase. Such acetylation of SUPT16H is recognized by bromodomain protein BRD4, which promotes protein stability of SUPT16H. We further demonstrated that SUPT16H-BRD4 associates with histone modification enzymes (EZH2, HDAC1) and affects histone marks (H3K9me3, H3K27me3 and H3ac). BRD4 is known to profoundly regulate interferon (IFN) signaling, while such function of SUPT16H has never been explored. Surprisingly, our results revealed that SUPT16H genetic knockdown via RNAi or pharmacological inhibition by using its inhibitor, curaxin 137 (CBL0137), results in the induction of IFNs and interferon-stimulated genes (ISGs). Through this mechanism, CBL0137 is shown to efficiently inhibit infection of multiple viruses, including Zika, influenza, and SARS-CoV-2. Furthermore, we demonstrated that CBL0137 also causes the remarkable activation of IFN signaling in natural killer (NK) cells, which promotes the NK-mediated killing of virus-infected cells in a co-culture system using human primary NK cells. Overall, our studies unraveled the previously un-appreciated role of FACT complex in regulating IFN signaling in both epithelial and NK cells, and also proposed the novel application of CBL0137 to treat viral infections.

The dNTPase activity of SAMHD1 is important for its suppression of innate immune responses in differentiated monocytic cells.

Sterile alpha motif and HD domain-containing protein 1 (SAMHD1) is a deoxynucleoside triphosphohydrolase (dNTPase) with a nuclear localization signal (NLS). SAMHD1 suppresses innate immune responses to viral infection and inflammatory stimuli by inhibiting the NF-κB and type I interferon (IFN-I) pathways. However, whether the dNTPase activity and nuclear localization of SAMHD1 are required for its suppression of innate immunity remains unknown. Here, we report that the dNTPase activity, but not nuclear localization of SAMHD1, is important for its suppression of innate immune responses in differentiated monocytic cells. We generated monocytic U937 cell lines stably expressing WT SAMHD1 or mutated variants defective in dNTPase activity (HD/RN) or nuclear localization (mNLS). WT SAMHD1 in differentiated U937 cells significantly inhibited lipopolysaccharide-induced expression of tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) mRNAs, as well as IFN-α, IFN-ß, and TNF-α mRNA levels induced by Sendai virus infection. In contrast, the HD/RN mutant did not exhibit this inhibition in either U937 or THP-1 cells, indicating that the dNTPase activity of SAMHD1 is important for suppressing NF-κB activation. Of note, in lipopolysaccharide-treated or Sendai virus-infected U937 or THP-1 cells, the mNLS variant reduced TNF-α or IFN-ß mRNA expression to a similar extent as did WT SAMHD1, suggesting that SAMHD1-mediated inhibition of innate immune responses is independent of SAMHD1's nuclear localization. Moreover, WT and mutant SAMHD1 similarly interacted with key proteins in NF-κB and IFN-I pathways in cells. This study further defines the role and mechanisms of SAMHD1 in suppressing innate immunity.

SAMHD1 Impairs HIV-1 Gene Expression and Negatively Modulates Reactivation of Viral Latency in CD4+ T Cells.

Sterile alpha motif and HD domain-containing protein 1 (SAMHD1) restricts human immunodeficiency virus type 1 (HIV-1) replication in nondividing cells by degrading intracellular deoxynucleoside triphosphates (dNTPs). SAMHD1 is highly expressed in resting CD4+ T cells, which are important for the HIV-1 reservoir and viral latency; however, whether SAMHD1 affects HIV-1 latency is unknown. Recombinant SAMHD1 binds HIV-1 DNA or RNA fragments in vitro, but the function of this binding remains unclear. Here we investigate the effect of SAMHD1 on HIV-1 gene expression and reactivation of viral latency. We found that endogenous SAMHD1 impaired HIV-1 long terminal repeat (LTR) activity in monocytic THP-1 cells and HIV-1 reactivation in latently infected primary CD4+ T cells. Overexpression of wild-type (WT) SAMHD1 suppressed HIV-1 LTR-driven gene expression at a transcriptional level. Tat coexpression abrogated SAMHD1-mediated suppression of HIV-1 LTR-driven luciferase expression. SAMHD1 overexpression also suppressed the LTR activity of human T-cell leukemia virus type 1 (HTLV-1), but not that of murine leukemia virus (MLV), suggesting specific suppression of retroviral LTR-driven gene expression. WT SAMHD1 bound to proviral DNA and impaired reactivation of HIV-1 gene expression in latently infected J-Lat cells. In contrast, a nonphosphorylated mutant (T592A) and a dNTP triphosphohydrolase (dNTPase) inactive mutant (H206D R207N [HD/RN]) of SAMHD1 failed to efficiently suppress HIV-1 LTR-driven gene expression and reactivation of latent virus. Purified recombinant WT SAMHD1, but not the T592A and HD/RN mutants, bound to fragments of the HIV-1 LTR in vitro These findings suggest that SAMHD1-mediated suppression of HIV-1 LTR-driven gene expression potentially regulates viral latency in CD4+ T cells.IMPORTANCE A critical barrier to developing a cure for HIV-1 infection is the long-lived viral reservoir that exists in resting CD4+ T cells, the main targets of HIV-1. The viral reservoir is maintained through a variety of mechanisms, including regulation of the HIV-1 LTR promoter. The host protein SAMHD1 restricts HIV-1 replication in nondividing cells, but its role in HIV-1 latency remains unknown. Here we report a new function of SAMHD1 in regulating HIV-1 latency. We found that SAMHD1 suppressed HIV-1 LTR promoter-driven gene expression and reactivation of viral latency in cell lines and primary CD4+ T cells. Furthermore, SAMHD1 bound to the HIV-1 LTR in vitro and in a latently infected CD4+ T-cell line, suggesting that the binding may negatively modulate reactivation of HIV-1 latency. Our findings indicate a novel role for SAMHD1 in regulating HIV-1 latency, which enhances our understanding of the mechanisms regulating proviral gene expression in CD4+ T cells.

Development of single-chain variable fragments (scFv) against influenza virus targeting hemagglutinin subunit 2 (HA2).

Influenza A viruses (IAV) are widespread in birds and domestic poultry, occasionally causing severe epidemics in humans and posing health threats. Hence, the need to develop a strategy for prophylaxis or therapy, such as a broadly neutralizing antibody against IAV, is urgent. In this study, single-chain variable fragment (scFv) phage display technology was used to select scFv fragments recognizing influenza envelope proteins. The Tomlinson I and J scFv phage display libraries were screened against the recombinant HA2 protein (rHA2) for three rounds. Only the third-round elution sample of the Tomlinson J library showed high binding affinity to rHA2, from which three clones (3JA18, 3JA62, and 3JA78) were chosen for preparative-scale production as soluble antibody by E. coli. The clone 3JA18 was selected for further tests due to its broad affinity for influenza H1N1, H3N2 and H5N1. Simulations of the scFv 3JA18-HA trimer complex revealed that the complementarity-determining region of the variable heavy chain (VH-CDR2) bound the stem region of HA. Neutralization assays using a peptide derived from VH-CDR2 also supported the simulation model. Both the selected antibody and its derived peptide were shown to suppress infection with H5N1 and H1N1 viruses, but not H3N2 viruses. The results also suggested that the scFvs selected from rHA2 could have neutralizing activity by interfering with the function of the HA stem region during virus entry into target cells.

A novel missense mutation of the EDA gene in a Mongolian family with congenital hypodontia.

X-linked hypohidrotic ectodermal dysplasia (HED) is a rare disease characterized by the hypoplasia or absence of eccrine glands, dry skin, scant hair, and dental abnormalities. Here, we report a Mongolian family with congenital absence of teeth inherited in an X-linked fashion. The affected members of the family did not show other HED characteristics, except hypodontia. We successfully mapped the affected locus to chromosome Xq12-q13.1, and then found a novel missense mutation, c.193C>G, in the ectodysplasin A (EDA) gene in all affected males and carrier females. The mutation causes arginine to be replaced by glycine in codon 65 (R65G) in the juxtamembrane region of EDA. In addition, 33% (3/9) of female carriers have a skewed X-chromosome inactivation pattern. Our result strongly suggests that the c.193C>G mutation is the disease-causing mutation in this family.