Streptococcus suis serotype 2 (S. suis 2) is an important swine and human pathogen responsible for septicemia and meningitis. A novel gene, designated atl and encoding a major autolysin of S. suis 2 virulent strain HA9801, was identified and characterized in this study. The Atl protein contains 1,025 amino acids with a predicted molecular mass of 113 kDa and has a conserved N-acetylmuramoyl-L-alanine amidase domain. Recombinant Atl was expressed in Escherichia coli, and its bacteriolytic and fibronectin-binding activities were confirmed by zymography and Western affinity blotting. Two bacteriolytic bands were shown in the sodium dodecyl sulfate extracts of HA9801, while both were absent from the atl inactivated mutant. Cell chains of the mutant strain became longer than that of the parental strain. In the autolysis assay, HA9801 decreased to 20% of the initial optical density (OD) value, while the mutant strain had almost no autolytic activity. The biofilm capacity of the atl mutant was reduced ϳ30% compared to the parental strain. In the zebrafish infection model, the 50% lethal dose of the mutant strain was increased up to 5-fold. Furthermore, the adherence to HEp-2 cells of the atl mutant was 50% less than that of the parental strain. Based on the functional analysis of the recombinant Atl and observed effects of atl inactivation on HA9801, we conclude that Atl is a major autolysin of HA9801. It takes part in cell autolysis, separation of daughter cells, biofilm formation, fibronectinbinding activity, cell adhesion, and pathogenesis of HA9801. Bacteria produce several peptidoglycan hydrolases, some of which are autolysins able to disintegrate their own peptidoglycan saccules and lead to bacterial cell lysis in unfavorable conditions (44). Autolysins have been implicated in various biological functions, such as cell wall turnover, cell separation, cell division and antibiotic-induced autolysis (48,55). In addition to their biological functions, bacterial autolysins are also involved or implicated in the pathogenicity of Gram-positive bacteria. Intact autolytic function is required for full virulence in Streptococcus pneumoniae (7). Autolysin-deficient mutants, including a LytA mutant of S. pneumoniae (8), an AtlE mutant of Staphylococcus epidermidis (46), and Ami (36), Auto (11), p60 (41), and MurA (28) mutants of Listeria monocytogenes are less virulent in animal models than their parental strains.Streptococcus suis is an important zoonotic pathogen that causes a variety of serious diseases, including meningitis, arthritis, and septicemia and even sudden death in pigs and humans (35,49). Among the 35 serotypes of S. suis that have been described, S. suis serotype 2 (S. suis 2) is the most virulent and most frequently isolated serotype. Although a set of virulence factors have been identified, the pathogenic mechanisms of S. suis 2 are still unclear. Autolysins are believed to play an important role in cell wall metabolism and in the pathogenicity of bacteria (7). However, the concentration of autolysins in S....

The fetal-to-adult hemoglobin switch is regulated in a developmental stage-specific manner and reactivation of fetal hemoglobin (HbF) has therapeutic implications for treatment of b-thalassemia and sickle cell anemia, two major global health problems. Although significant progress has been made in our understanding of the molecular mechanism of the fetal-to-adult hemoglobin switch, the mechanism of epigenetic regulation of HbF silencing remains to be fully defined. Here, we performed whole-genome bisulfite sequencing and RNA sequencing analysis of the bone marrow-derived GYPA þ erythroid cells from b-thalassemia-affected individuals with widely varying levels of HbF groups (HbF R 95th percentile or HbF % 5th percentile) to screen epigenetic modulators of HbF and phenotypic diversity of b-thalassemia. We identified an ETS2 repressor factor encoded by ERF, whose promoter hypermethylation and mRNA downregulation are associated with high HbF levels in b-thalassemia. We further observed that hypermethylation of the ERF promoter mediated by enrichment of DNMT3A leads to demethylation of g-globin genes and attenuation of binding of ERF on the HBG promoter and eventually re-activation of HbF in b-thalassemia. We demonstrated that ERF depletion markedly increased HbF production in human CD34 þ erythroid progenitor cells, HUDEP-2 cell lines, and transplanted NCG-Kit-V831M mice. ERF represses g-globin expression by directly binding to two consensus motifs regulating g-globin gene expression. Importantly, ERF depletion did not affect maturation of erythroid cells. Identification of alterations in DNA methylation of ERF as a modulator of HbF synthesis opens up therapeutic targets for b-hemoglobinopathies.

Both PD1/PD-L1 and CD47 blockades have demonstrated limited activity in most subtypes of NHL save NK/T-cell lymphoma. The hemotoxicity with anti-CD47 agents in the clinic has been speculated to account for their limitations. Herein we describe a first-in-class and rationally designed bispecific antibody (BsAb), HX009, targeting PD1 and CD47 but with weakened CD47 binding, which selectively hones the BsAb for tumor microenvironment through PD1 interaction, potentially reducing toxicity. In vitro characterization confirmed: (1) Both receptor binding/ligand blockade, with lowered CD47 affinity; (2) functional PD1/CD47 blockades by reporter assays; (3) T-cell activation in Staphylococcal-enterotoxin-B-pretreated PBMC and mixed-lymphocyte-reaction. In vivo modeling demonstrated antitumor activity in Raji-B and Karpass-229-T xenograft lymphomas. In the humanized mouse syngeneic A20 B-lymphoma (huCD47-A20) HuGEMM model, which has quadruple knocked-in hPD1xhPD-L1xhCD47xhSIRPα genes and an intact autologous immune-system, a contribution of effect is demonstrated for each targeted biologic (HX008 targeting PD1 and SIRPα-Fc targeting CD47), which is clearly augmented by the dual targeting with HX009. Lastly, the expression of the immune-checkpoints PD-L1/L2 and CD47 seemed co-regulated among a panel of lymphoma-derived-xenografts, where HX009 maybe more effective in those with upregulated CD47. Our data warrants HX009’s further clinical development for treating NHLs.

The International Mouse Phenotyping Consortium (IMPC) is generating and phenotyping null mutations for every protein-coding gene in the mouse. The IMPC now uses Cas9, a programmable RNA-guided nuclease that has revolutionized mouse genome editing and increased capacity and flexibility to efficiently generate null alleles in the C57BL/6N strain. In addition to being a valuable novel and accessible research resource, the production of >3,300 knockout mouse lines using comparable protocols provides a rich dataset to analyze experimental and biological variables affecting in vivo null allele engineering with Cas9. Mouse line production has two critical steps - generation of founders with the desired allele and germline transmission (GLT) of that allele from founders to offspring. Our analysis identified that whether a gene is essential for viability was the primary factor influencing successful production of null alleles. Collectively, our findings provide best practice recommendations for generating null alleles in mice using Cas9; these recommendations may be applicable to other allele types and species.

NCG (GPT strain ID: T001475), one of the highly immune-deficient mouse models generated so far, is ideal for engraftment of human tissues and cells, such as patient derived tumors (PDX), human cancer cell lines (CDX), human peripheral blood mononuclear cells (PBMC) and human hematopoietic stem cells (HSCs). NK cells that are a critical component of the innate immune system have diverse biological functions, such as recognizing and killing viral-infected and neoplastic cells. Human HSCs (CD34+) could reconstitute human T but not NK cells in NCG mice. The cytokine Interleukin 15 (IL-15) plays a critical role in the generation of NK cells from HSCs. IL-15 is produced by non-lymphoid cells, including monocytes, dendritic and bone marrow stromal cells. Human and mouse IL-15 are only 70% identical to each other in primary amino acid sequence. Mouse IL-15 poorly supports the reconstitution of human NK cells. To overcome this problem, several lines of transgenic mice that express human IL-15 (hIL-15) have been established. However, the non-physiological levels of hIL-15 expression are detrimental to human immune system reconstitution.In the current study, we developed hIL-15 knock-in in NCG mice (NCG-hIL-15), in which the mouse IL-15 (mIL-15) gene was replaced by the hIL-15 gene. We quantified the mRNA expression of hIL-15 and found that the levels of hIL-15 expression in the BM, liver, lung, and small intestine of NCG-hIL-15 mice were similar to those of mIL-15 in NCG mice.Based on these data, we expect that NCG-hIL-15 mice can efficiently support the development, maturation and function of human NK cells. In the future, we will further study human NK cell engraftment and human NK cell-mediated cancer immunotherapy in NCG-hIL-15 mice. Taken together, our newly developed NCG-hIL-15 mice offer a novel mouse model for studying human NK cell biology and human NK-mediated cancer immunotherapy in vivo. Disclosures Ju: GemPharmatech Co., Ltd: Employment. Zhang:GemPharmatech Co., Ltd: Employment. Wu:GemPharmatech Co., Ltd: Employment. Tang:GemPharmatech Co., Ltd: Employment. Li:GemPharmatech Co., Ltd: Employment. Zhao:GemPharmatech Co., Ltd: Employment. Wang:GemPharmatech Co., Ltd: Employment. Gao:GemPharmatech Co., Ltd: Employment.