Early identification of infections caused by carbapenemase-producing Enterobacterales (CPE) can help to optimize patient treatment and improve outcome. In this study, protocols for rapid detection of carbapenemase production directly from positive blood cultures were developed applying a concentration and hemolysis step before a test for carbapenemase production was performed. Four different methods (three modified colorimetric assays [β-Carba, bcCarba NP, and NeoRapid Carb] and a variation of the carbapenem inactivation method [CIM] test with blood cultures [bcCIM]) were assessed on blood cultures spiked with 185 different molecularly characterized Enterobacterales isolates. The challenge collection included 81 carbapenemase-negative isolates and 104 CPEs (OXA-48 [n = 25], NDM [n = 20], KPC [n = 18], VIM [n = 25], GIM [n = 5], OXA-48-like [n = 9], and OXA-48-like plus NDM [n = 2]). The sensitivity/specificity was 99.0%/95.1% for bcCarba NP, 99.0%/91.4% for NeoRapid Carb, 100%/95.1% for β-Carba and 100%/100% for bcCIM. Weakly hydrolyzing carbapenemases (e.g., OXA-48-like) were also well detected by the assays. The time to result was 20 to 45 min for β-Carba, 2 to 3 h for bcCarba NP, 2.5 to 2 h for NeoRapid Carb, and 18 to 24 h for bcCIM. In conclusion, all assays demonstrated good detection of CPE. The protocols can be easily implemented in any clinical microbiology laboratory and could help to optimize therapy early in bloodstream infections by CPE.

Mixed lineage leukemia (MLL/KMT2A) rearrangements (MLL-r) are one of the most frequent chromosomal aberrations in acute myeloid leukemia. We evaluated the function of Meningioma 1 (MN1), a co-factor of HOXA9 and MEIS1, in human and murine MLL-rearranged leukemia by CRISPR-Cas9 mediated deletion of MN1. MN1 was required for in vivo leukemogenicity of MLL positive murine and human leukemia cells. Loss of MN1 inhibited cell cycle and proliferation, promoted apoptosis and induced differentiation of MLL-rearranged cells. Expression analysis and chromatin immunoprecipitation with sequencing from previously reported data sets demonstrated that MN1 primarily maintains active transcription of HOXA9 and HOXA10, which are critical downstream genes of MLL, and their target genes like BCL2, MCL1 and Survivin. Treatment of MLL-rearranged primary leukemia cells with anti-MN1 siRNA significantly reduced their clonogenic potential in contrast to normal CD34+ hematopoietic progenitor cells, suggesting a therapeutic window for MN1 targeting. In summary, our findings demonstrate that MN1 plays an essential role in MLL fusion leukemias and serve as a therapeutic target in MLL-rearranged acute myeloid leukemia.

F-box protein 31 (FBXO31) is a reported putative tumor suppressor, and its inactivation due to loss of heterozygosity is associated with cancers of different origins. An emerging body of literature has documented FBXO31's role in preserving genome integrity following DNA damage and in the cell cycle. However, knowledge regarding the role of FBXO31 during normal cell-cycle progression is restricted to its functions during the G2/M phase. Interestingly, FBXO31 levels remain high even during the early G1 phase, a crucial stage for preparing the cells for DNA replication. Therefore, we sought to investigate the functions of FBXO31 during the G1 phase of the cell cycle. Here, using flow cytometric, biochemical, and immunofluorescence techniques, we show that FBXO31 is essential for maintaining optimum expression of the cell-cycle protein cyclin A for efficient cell-cycle progression. Stable FBXO31 knockdown led to atypical accumulation of cyclin A during the G1 phase, driving premature DNA replication and compromised loading of the minichromosome maintenance complex, resulting in replication from fewer origins and DNA double-strand breaks. Because of these inherent defects in replication, FBXO31-knockdown cells were hypersensitive to replication stress-inducing agents and displayed pronounced genomic instability. Upon entering mitosis, the cells defective in DNA replication exhibited a delay in the prometaphase-to-metaphase transition and anaphase defects such as lagging and bridging chromosomes. In conclusion, our findings establish that FBXO31 plays a pivotal role in preserving genomic integrity by maintaining low cyclin A levels during the G1 phase for faithful genome duplication and segregation.

The genetic causes for most male infertility due to severe asthenozoospermia remain unclear.

Vaccines aimed at inducing T cell responses to protect against human immunodeficiency virus (HIV) infection have been under development for more than 15 years. Replication-defective adenovirus (rAd) vaccine vectors are at the forefront of this work and have been tested extensively in the simian immunodeficiency virus (SIV) challenge macaque model. Vaccination with rAd vectors coding for SIV Gag or other nonenvelope proteins induces T cell responses that control virus load but disappointingly is unsuccessful so far in preventing infection, and attention has turned to inducing antibodies to the envelope. However, here we report that Mauritian cynomolgus macaques (MCM), Macaca fascicularis, vaccinated with unmodified SIV gag alone in a DNA prime followed by an rAd boost exhibit increased protection from infection by repeated intrarectal challenge with low-dose SIVmac251. There was no evidence of infection followed by eradication. A significant correlation was observed between cytokine expression by CD4 T cells and delayed infection. Vaccination with gag fused to the ubiquitin gene or fragmented, designed to increase CD8 magnitude and breadth, did not confer resistance to challenge or enhance immunity. On infection, a significant reduction in peak virus load was observed in all vaccinated animals, including those vaccinated with modified gag These findings suggest that a nonpersistent viral vector vaccine coding for internal virus proteins may be able to protect against HIV type 1 (HIV-1) infection. The mechanisms are probably distinct from those of antibody-mediated virus neutralization or cytotoxic CD8 cell killing of virus-infected cells and may be mediated in part by CD4 T cells.IMPORTANCE The simian immunodeficiency virus (SIV) macaque model represents the best animal model for testing new human immunodeficiency virus type 1 (HIV-1) vaccines. Previous studies employing replication-defective adenovirus (rAd) vectors that transiently express SIV internal proteins induced T cell responses that controlled virus load but did not protect against virus challenge. However, we show for the first time that SIV gag delivered in a DNA prime followed by a boost with an rAd vector confers resistance to SIV intrarectal challenge. Other partially successful SIV/HIV-1 protective vaccines induce antibody to the envelope and neutralize the virus or mediate antibody-dependent cytotoxicity. Induction of CD8 T cells which do not prevent initial infection but eradicate infected cells before infection becomes established has also shown some success. In contrast, the vaccine described here mediates resistance by a different mechanism from that described above, which may reflect CD4 T cell activity. This could indicate an alternative approach for HIV-1 vaccine development.

The human cerebral cortex is a complex structure with tightly interconnected excitatory and inhibitory neuronal networks. In order to study human cortical function, we recently developed a method to generate cortical neurons from human induced pluripotent stem cells (hiPSCs) that form both excitatory and inhibitory neuronal networks resembling the composition of the human cortex. These cultures and organoids recapitulate neuronal populations representative of the six cortical layers and a balanced excitatory and inhibitory network that is functional and homeostatically stable. To determine whether hiPSC-derived neurons can integrate and retain physiologic activities in vivo, we labeled hiPSCs with red fluorescent protein (RFP) and introduced hiPSC-derived neural progenitors to rat brains. Efficient neural induction, followed by differentiation resulted in a RFP+ neural population with traits of forebrain identity and a balanced synaptic activity composed of both excitatory neurons and inhibitory interneurons. Ten weeks after transplantation, grafted cells structurally integrated into the rat forebrain. Remarkably, these hiPSC-derived neurons were able to fire, exhibiting both excitatory and inhibitory postsynaptic currents, which culminates in the establishment of neuronal connectivity with the host circuitry. This study demonstrates that neural progenitors derived from hiPSCs can differentiate into functional cortical neurons and can participate in neural network activity through functional synaptic integration in vivo, thereby contributing to information processing.

Long non-coding RNAs (lncRNAs) are transcripts longer than 200 nt that are involved in cardiovascular diseases (CVDs). To determine whether lncRNAs are involved in stable angina pectoris (SAP), we analysed the expression profile of lncRNAs and mRNAs on a genome-wide scale in SAP of Uyghur population. Five pairs of SAP patients and healthy controls were screened by an Agilent microarray (human lncRNA + mRNA Array V4.0). Quantitative real-time polymerase chain reaction (qRT-PCR) was used to validate the lncRNA expression levels in 50 SAP and 50 controls. Data analyses were performed using R and Bioconductor. A total of 1871 up- and 231 down-regulated lncRNAs were identified to be differentially expressed in the peripheral blood mononuclear cells (PBMCs). Microarray analysis results identified the lncRNAs NR_037652.1, ENST00000607654.1, ENST00000589524.1 and uc004bhb.3, which were confirmed by qRT-PCR. Among screened lncRNAs, the annotation result of their co-expressed mRNAs showed that the most significantly related pathways were the NF-κB signalling pathway, apoptosis and the p53 signalling pathway, while the main significantly related diseases were the cholesterol, calcium and coronary disease. Our study indicated that clusters of lncRNAs were significantly differentially expressed between SAP patients and matched controls. These lncRNAs may play a significant role in SAP development and could serve as biomarkers and potential targets for the future treatment of SAP.

Here we describe baseline validation studies and field performance of a research-use-only chemiluminescent multiplex serology panel for measles, mumps, rubella, and varicella-zoster virus used with dried blood spots in support of the 2013-2014 Democratic Republic of the Congo Demographic and Health Survey. Characterization of the panel using U.S. FDA-cleared commercial kits shows good concordance for measles, mumps, rubella, and varicella-zoster with average sensitivity across assays of 94.9% and an average specificity of 91.4%. As expected, performance versus available standards validated for plaque-reduction assays does not provide a 1:1 correspondence with international units and yet demonstrates excellent linearity (average Hill's slope = 1.02) and ∼4 logs of dynamic range. In addition, for the four assays, the multiplexed format allowed for inclusion of three positive and two negative controls for each sample. A prototype Dynex Multiplier chemiluminescent automated immunoassay instrument with a charge-coupled device camera provided a rugged and robust processing and data acquisition platform. Performance of a multiplex instrument for serological testing in a substantially resource-limited environment shows excellent reproducibility, minimal cross-reactivity, and a clear discrimination between specific assays and should be considered a viable option for future serosurveys.IMPORTANCE The critical evaluation of immunization programs is key to identifying areas of suboptimal vaccination coverage, monitoring activities, and aiding development of public health policy. For evaluation of vaccine effectiveness, direct antibody binding assay methods, including enzyme immunoassay, enzyme-linked fluorescence assays, and indirect immunofluorescence assay, are most commonly used for detection of IgG antibodies. However, despite their well-demonstrated, reliable performance, they can be labor-intensive and time-consuming and require separate assays for each individual marker. This necessitates increased sample volumes, processing time, and personnel, which may limit assessment to a few key targets in resource-limited settings, that is, low- and middle-income locations where funding for public health or general infrastructure that directly impacts public health is restricted, limiting access to equipment, infrastructure, and trained personnel. One solution is a multiplexed immunoassay, which allows for the detection of multiple analytes in a single reaction for increased efficiency and rapid surveillance of infectious diseases in limited-resource settings. Thus, the scope of the project precluded a full validation, and here we present abbreviated validation studies demonstrating adequate sensitivity, specificity, and reproducibility.

Eukaryotic ribosome biogenesis is a complicated and highly conserved biological process. A critical step in ribosome biogenesis is the translocation of the immature ribosomal subunits from the nucleoplasm, across the nucleopore complex, to the cytoplasm where they undergo final maturation. Many nonribosomal proteins are needed to facilitate export of the ribosomal subunits, and one complex participating in export of the pre-60S in Saccharomyces cerevisiae is the heterodimer Mex67-Mtr2. In Trypanomsoma brucei, the process of ribosome biogenesis differs from the yeast process in key steps and is not yet fully characterized. However, our laboratory has previously identified the trypanosome-specific proteins P34/P37 and has shown that P34/P37 are necessary for the formation of the 5S ribonuclear particle (RNP) and for the nuclear export of the pre-60S subunit. We have also shown that loss of TbMex67 or TbMtr2 leads to aberrant ribosome formation, rRNA processing, and polysome formation in T. brucei In this study, we characterize the interaction of TbMex67 and TbMtr2 with the components of the 5S RNP (P34/P37, L5 and 5S rRNA) of the 60S subunit. We demonstrate that TbMex67 directly interacts with P34 and L5 proteins as well as 5S rRNA, while TbMtr2 does not. Using protein sequence alignments and structure prediction modeling, we show that TbMex67 lacks the amino acids previously shown to be essential for binding to 5S rRNA in yeast and in general aligns more closely with the human orthologue (NXF1 or TAP). This work suggests that the T. brucei Mex67-Mtr2 binds ribosomal cargo differently from the yeast system.IMPORTANCETrypanosoma brucei is the causative agent for both African sleeping sickness in humans and nagana in cattle. Ribosome biogenesis in these pathogens requires both conserved and trypanosome-specific proteins to coordinate in a complex pathway. We have previously shown that the trypanosome-specific proteins P34/P37 are essential to the interaction of the TbNmd3-TbXpoI export complex with the 60S ribosomal subunits, allowing their translocation across the nuclear envelope. Our recent studies show that the trypanosome orthologues of the auxiliary export proteins TbMex67-TbMtr2 are required for ribosome assembly, proper rRNA processing, and polysome formation. Here we show that TbMex67-TbMtr2 interact with members of the 60S ribosomal subunit 5S RNP. Although TbMex67 has a unique structure among the Mex67 orthologues and forms unique interactions with the 5S RNP, particularly with trypanosome-specific P34/P37, it performs a conserved function in ribosome assembly. These unique structures and parasite-specific interactions may provide new therapeutic targets against this important parasite.

Human longevity is heritable, but genome-wide association (GWA) studies have had limited success. Here, we perform two meta-analyses of GWA studies of a rigorous longevity phenotype definition including 11,262/3484 cases surviving at or beyond the age corresponding to the 90th/99th survival percentile, respectively, and 25,483 controls whose age at death or at last contact was at or below the age corresponding to the 60th survival percentile. Consistent with previous reports, rs429358 (apolipoprotein E (ApoE) ε4) is associated with lower odds of surviving to the 90th and 99th percentile age, while rs7412 (ApoE ε2) shows the opposite. Moreover, rs7676745, located near GPR78, associates with lower odds of surviving to the 90th percentile age. Gene-level association analysis reveals a role for tissue-specific expression of multiple genes in longevity. Finally, genetic correlation of the longevity GWA results with that of several disease-related phenotypes points to a shared genetic architecture between health and longevity.

Hypoxia-inducible factor (HIF)-1α is a crucial transcription factor that regulates the expression of target genes involved in angiogenesis. Prolyl hydroxylase 2 (PHD2) dominantly hydroxylates two highly conserved proline residues of HIF-1α to promote its degradation. This study was designed to construct an intrabody against PHD2 that can inhibit PHD2 activity and promote angiogenesis. Single-chain variable fragment (scFv) against PHD2, INP, was isolated by phage display technique and was modified with an endoplasmic reticulum (ER) sequence to obtain ER-retained intrabody against PHD2 (ER-INP). ER-INP was efficiently expressed and bound to PHD2 in cells, significantly increased the levels of HIF-1α, and decreased hydroxylated HIF-1α in human embryonic kidney cell line (HEK293) cells and mouse mononuclear macrophage leukaemia cell line (RAW264.7) cells. ER-INP has shown distinct angiogenic activity both in vitro and in vivo, as ER-INP expression significantly promoted the migration and tube formation of human umbilical vein endothelial cells (HUVECs) and enhanced angiogenesis of chick chorioallantoic membranes (CAMs). Furthermore, ER-INP promoted distinct expression and secretion of a range of angiogenic factors. To the best of our knowledge, this is the first study to report an ER-INP intrabody enhancing angiogenesis by blocking PHD2 activity to increase HIF-1α abundance and activity. These results indicate that ER-INP may play a role in the clinical treatment of tissue injury and ischemic diseases in the future.

Choline phosphate-based delivery systems can target the acidic tumor microenvironment. In this study, we set out to evaluate the diagnostic value of Choline phosphate cytidylyltransferase-α (CCTα) in laryngeal squamous cell cancer (LSCC). The expression of CCTα was detected using immunohistochemistry in 50 LSCC patients' tissues and 16 vocal polyps as control group. Then, clinical data was collected and we used receiver operating characteristic curve (ROC) to estimate the potential of CCTα as diagnostic biomarker. We found CCTα levels to be significantly high in the tissues derived from LSCC patients, (p < 0.001). Further, we observed a positive correlation of CCTα with tumor size (p < 0.001), TNM stage (p < 0.001), lymph node metastasis (p < 0.001) as well as the grade of LSCC malignancy (p < 0.001). Furthermore, AUC was determined to be 0.939 by ROC, and the optimal cutoff value 3.100, with 76.0% sensitivity and 100% specificity. We also found an epigenetic basis of CCTα over-expression in LSCC tissues with significantly reduced methylation of CCTα in LSCC tissues, compared to vocal polyps (p < 0.001). These results support epigenetically-induced over-expression of CCTα as a potential diagnostic marker for LSCC.

Actinium-225 (225Ac) can be produced from a Thorium-229/Radium-225 (229Th/225Ra) generator, from high/low energy proton irradiated natural Thorium or Radium-226 target. Titanium based ion exchanger were evaluated for purification of 225Ac. Poorly crystalline silicotitanate (PCST) ion exchanger had high selectivity for Ba, Ag and Th. 225Ac was received with trace amounts of 227Ac, 227Th and 223Ra, and the solution was used to evaluate the retention of the isotopes on PCST ion exchanger. Over 90% of the 225Ac was recovered from PCST, and the radiopurity was >99% (calculated based on 225Ac, 227Th, and 223Ra). The capacity of the PCST inorganic ion exchange for Barium and 232Th was determined to be 24.19 mg/mL for Barium and 5.05 mg/mL for Thorium. PCST ion exchanger could separate 225Ac from isotopes of Ra and Th, and the process represents an interesting one step separation that could be used in an 225Ac generator from 225Ra and/or 229Th. Capacity studies indicated PCST could be used to separate 225Ac produced on small 226Ra targets (0.3-1 g), but PCST did not have a high enough capacity for production scale Th targets (50-100 g).

Cell density regulates many aspects of cell properties and behaviors including metabolism, growth, cytoskeletal structure and locomotion. Importantly, the responses by cultured cells to density signals also uncover key mechanisms that govern animal development and diseases in vivo. Here we characterized a density-responsive reporter system in transgenic Drosophila S2 cells. We show that the reporter genes are strongly induced in a cell density-dependent and reporter-independent fashion. The rapid and reversible induction occurs at the level of mRNA accumulation. We show that multiple DNA elements within the transgene sequences, including a metal response element from the metallothionein gene, contribute to the reporter induction. The reporter induction correlates with changes in multiple cell density and growth regulatory pathways including hypoxia, apoptosis, cell cycle and cytoskeletal organization. Potential applications of such a density-responsive reporter will be discussed.

Atrophic maxillary ridges present a challenge in the field of oral implantology. Autologous bone is still considered the gold standard grafting material, but the increased morbidity and surgical complications represent a major drawback for its use. The aim of this study was to assess the efficacy of an off-the-shelf cell-seeded bone biomaterial for mandibular bone augmentation, compared to its acellular counterpart. We used a rat model to test the osteogenic properties of bone marrow-derived mesenchymal stromal cells (MSCs)-seeded bone microparticles compared to acellular bone microparticles alone. Rats were euthanized at 4 and 8 weeks, and results analyzed using micro-CT imaging, histology (H&E, Masson's Trichrome), histomorphometry and immunohistology (Tartrate-Resistant Acid Phosphatase-TRAP, Osteocalcin and human specific anti-mitochondria antibodies). Micro-CT analysis demonstrated that the cell-seeded biomaterial achieved significantly more bone volume formation at 4 weeks (22.75 ± 2.25 mm3 vs 12.34 ± 2.91 mm3, p = 0.016) and at 8 weeks (64.95 ± 5.41 mm3 vs 42.73 ± 10.58 mm3, p = 0.029), compared to the acellular bone microparticles. Histology confirmed that the cell-seeded biomaterial was almost completely substituted at 8 weeks, in opposition to the acellular biomaterial group. Immunohistochemical analysis showed a significantly higher number of TRAP and Osteocalcin positive cells at 4 weeks in the cell-seeded group compared to the acellular group, thereby demonstrating a higher rate of bone remodeling in the presence of MSCs. The grafted human cells remained viable and were detected up to at least 8 weeks, as observed using the human specific anti-mitochondria antibody. This off-the-shelf material available in unlimited quantities could therefore represent a significant advance in the field of mandibular bone augmentation by providing a larger volume of new bone formation in a shorter time.

Artificial intelligence (AI) is expected to support clinical judgement in medicine. We constructed a new predictive model for diabetic kidney diseases (DKD) using AI, processing natural language and longitudinal data with big data machine learning, based on the electronic medical records (EMR) of 64,059 diabetes patients. AI extracted raw features from the previous 6 months as the reference period and selected 24 factors to find time series patterns relating to 6-month DKD aggravation, using a convolutional autoencoder. AI constructed the predictive model with 3,073 features, including time series data using logistic regression analysis. AI could predict DKD aggravation with 71% accuracy. Furthermore, the group with DKD aggravation had a significantly higher incidence of hemodialysis than the non-aggravation group, over 10 years (N = 2,900). The new predictive model by AI could detect progression of DKD and may contribute to more effective and accurate intervention to reduce hemodialysis.

On May 1, 2018, a magnitude 5.0 earthquake heralded the collapse of the Pu'u O'o Vent on the middle East Rift Zone (ERZ) of Kilauea Volcano, active since 1983. Increased seismicity was recorded on the middle to lower ERZ from April 30 until May 2, 2018. The active lava lakes within both Pu'u O'o Vent and Halema'uma'u Crater began to drain and the summit caldera began to deflate, with the summit collapse ending on August 2, 2018 and lower ERZ eruptive lava activity ending by 4 September 2018. Herein we report on elevated 3He/4He ratios in steaming vents in the lower ERZ from samples collected in early September 2017. Gas isotopic measurements were made with a new, field-portable He isotope detector capable of sub-daily monitoring of the 3He/4He ratio. When corrected for air contamination, these values exceed those previously reported for Kilauea by nearly twofold, resembling a purer hotspot plume signature, such as those measured directly over the mantle plume at Loihi Seamount to the SE of Hawaii Island, and in older basalt flows when Kilauea and its sister Hawaiian shield volcanoes were located more directly over the plume. The discovery, which presages the eruption there by more than eight months, suggests that we either sampled a 3He/4He rich magma already in place in the lower ERZ or a shallow groundwater reservoir in the lower ERZ (Puna district) with anomalously low values of 4He relative to their 3He/4He ratio, similar to previous findings there and suggestive of a previously unknown He isotopic fractionation.

We hypothesized that clinical process improvement strategies can reduce frequency of motion artifacts and expiratory phase scanning in chest CT. We reviewed 826 chest CT to establish the baseline frequency. Per clinical process improvement guidelines, we brainstormed corrective measures and priority-pay-off matrix. The first intervention involved education of CT technologists, following which 795 chest CT were reviewed. For the second intervention, instructional videos on optimal breath-hold were shown to 245 adult patients just before their chest CT. Presence of motion artifacts and expiratory phase scanning was assessed. We also reviewed 311 chest CT scans belonging to a control group of patients who did not see the instructional videos. Pareto and percentage run charts were created for baseline and post-intervention data. Baseline incidence of motion artifacts and expiratory phase scanning in chest CT was 35% (292/826). There was no change in the corresponding incidence following the first intervention (36%; 283/795). Respiratory motion and expiratory phase chest CT with the second intervention decreased (8%, 20/245 patients). Instructional videos for patients (and not education and training of CT technologists) reduce the frequency of motion artifacts and expiratory phase scanning in chest CT.

Pathway analysis allows us to gain insights into a comprehensive understanding of the molecular mechanisms underlying cancers. Currently, high-throughput multi-omics data and various types of large-scale biological networks enable us to identify cancer-related pathways by comprehensively analyzing these data. Combining information from multidimensional data, pathway databases and interaction networks is a promising strategy to identify cancer-related pathways. Here we present a novel network-based approach for integrative analysis of DNA methylation and gene expression data to extend original pathways. The results show that the extension of original pathways can provide a basis for discovering new components of the original pathway and understanding the crosstalk between pathways in a large-scale biological network. By inputting the gene lists of the extended pathways into the classical gene set analysis (ORA and FCS), we effectively identified the altered pathways which are correlated well with the corresponding cancer. The method is evaluated on three datasets retrieved from TCGA (BRCA, LUAD and COAD). The results show that the integration of DNA methylation and gene expression data through a network of known gene interactions is effective in identifying altered pathways.

Anaerobic bacteria represent an overlooked rich source of biological and chemical diversity. Due to the challenge of cultivation and genetic intractability, assessing the capability of their biosynthetic gene clusters (BGCs) for secondary metabolite production requires an efficient heterologous expression system. However, this kind of host system is still unavailable. Here, we use the facultative anaerobe Streptococcus mutans UA159 as a heterologous host for the expression of BGCs from anaerobic bacteria. A natural competence based large DNA fragment cloning (NabLC) technique was developed, which can move DNA fragments up to 40-kb directly and integrate a 73.7-kb BGC to the genome of S. mutans UA159 via three rounds of NabLC cloning. Using this system, we identify an anti-infiltration compound, mutanocyclin, from undefined BGCs from human oral bacteria. We anticipate this host system will be useful for heterologous expression of BGCs from anaerobic bacteria.