Mutations in VMK1, a mitogen-activated protein kinase gene, affect microsclerotia formation and pathogenicity in Verticillium dahliae

Verticillium dahliae is an important soil-borne fungal pathogen that causes vascular wilt diseases in a large variety of important crop plants. Due to its persistence in the soil, control of Verticillium wilt relies heavily on soil fumigation. The global ban on methyl bromide, a highly effective soil fumigant, poses an urgent need to develop alternative control measures against Verticillium wilt; and these might be more forthcoming with a better understanding of the molecular and cellular mechanisms that underpin the pathogenicity of V. dahliae. In this study, we assessed the role in growth, development, and pathogenicity of VMK1, a gene encoding a mitogen-activated protein (MAP) kinase (hence, Verticillium MAP Kinase 1). Disruption of VMK1 via Agrobacterium tumefaciens-mediated transformation, in two V. dahliae isolates, one from lettuce and the other from tomato, resulted in severely reduced virulence in diverse host plants, suggesting that VMK1 is essential for pathogenicity and that the MAP kinase-mediated signaling pathway has a conserved role in fungal pathogenicity. The vmk1 mutants also exhibited reduced conidiation and microsclerotia formation, suggesting that the gene is important for multiple cellular processes. P.R. and R.G.B. equally contributed to the work     

Study on pathogenic genes of dwarfism disease by next-generation sequencing

BACKGROUNDThere are many factors that lead to dwarfism, and the mechanism has not yet been elucidated. Next-generation sequencing may identify candidate-related gene mutations, which may clarify the molecular cause.AIMTo analyze genetic variation by using a constructed panel related to dwarfism by utilizing next-generation sequencing platform sequencing analysis to screen candidate-related gene mutations.METHODSPhysical and laboratory characteristics, including clinical examination, growth hormone drug challenge test, serum insulin-like growth factor-1 (IGF-1), IGF binding protein 3, other related tests, imaging examination, and chromosome karyotyping, were analyzed. Next-generation sequencing was performed to analyze pathogenicity variability.RESULTSIn the 39 dwarfism patients, 10 had pathogenicity variability. Gene variation was found in the OBSL1, SLC26A2, PTPN11, COL27AI, HDAC6, CUL7, FGFR3, DYNC2H1, GH1, and ATP7B genes. Of the 10 patients with pathogenicity variability, the related physical characteristics included double breast development and growth hormone deficiency, enuresis and indirect inguinal hernia on the left, two finger distance of 70.2 cm, head circumference of 49.2 cm, ischium/lower body length of 1.8 cm, weak limb muscles, and partial growth hormone deficiency. After 6 mo of growth hormone therapy, the concentrations of IGF-1 and IGF binding protein 3 increased from 215.2 ± 170.3 to 285.0 ± 166.0 and 3.9 ± 1.4 to 4.2 ± 1.1, respectively.CONCLUSIONOBSL1, SLC26A2, PTPN11, COL27AI, HDAC6, CUL7, FGFR3, DYNC2H1, GH1, and ATP7B genes may be related to the incidence of dwarfism, and more research needs to be performed to elucidate the mechanism.     

Elucidation of the functional role of flagella in virulence and ecological traits of Pseudomonas cichorii using flagella absence (ΔfliJ) and deficiency (ΔfliI) mutants

Understanding the infection mechanisms of pathogens will lead to better management of the associated diseases. The flagella of these pathogens play significant roles not only in bacterial motility, but also in virulence. In the present study, two genes involved in flagella construction, fliJ and fliI of Pseudomonas cichorii, were analyzed. The results revealed that these genes are vital for flagella formation and play significant roles not only in motility, but also in virulence. When we inoculated host plants with fliI- and fliJ-defective mutants (ΔfliJ and ΔfliI) through the dipping method, the degree of disease severity caused by both mutants was significantly reduced compared to those of the wild-type. However, the virulence of ΔfliI was stronger than that of ΔfliJ. Electron microscope observation, and swarming and leaf attachment assays indicated a reduced number of flagella in ΔfliI, but not complete absence, because of the presence of another copy of fliI. Furthermore, a vacuum infiltration assay revealed that flagella are indispensable in the pre- and post-penetration stages for complete virulence. Overall, we created semi-defective (ΔfliI) and completely defective (ΔfliJ) mutants and elucidated the fact that flagella play significant roles in virulence of the pathogen at different stages of the infection process.     

克拉玛依地区的利什曼病 Ⅲ.大沙鼠体内利什曼原虫的形态及其对实验动物致病力的研究

在新疆克拉玛依的小拐和白碱滩两地,从20只大沙鼠的耳组织徐片上查出9只有利什曼原虫的感染。经测量69个原虫,平均大小为4.71±0.71×2.35±0.44μm,t试验结果显示,该地大沙鼠体内的利什曼原虫较沙鼠利什曼明显为小,与硕大利什曼原虫的形态比较,也有显著不同。 动物实验感染结果表明,该地大沙鼠体内的利什曼原虫在接种到BALB/c小鼠的足垫皮下后。可使小鼠产生皮肤溃疡和转移性皮肤损害,小鼠最后死于全身性感染。在远交系小鼠(昆明株)的足垫组织内,利什曼原虫可引起足垫局部短期肿胀,旋后消退,在外观正常的足垫皮下组织内,原虫可持续7个月以上。当原虫被注入黑线仓鼠的睾丸内后,产生睾丸局部感染,利什曼原虫主要寄生在鼠睾间质部位的巨噬细胞内,在曲细精管内的一些塞氏细胞中也有原虫寄生,偶而也发生转移性皮损。在长爪沙鼠耳组织内,原虫能持续14个月以上,并且可使鼠耳发生溃疡。 上述各项观察和实验结果表明,克拉玛依大沙鼠体内的利什曼原虫在形态大小、对4种实验动物所致的病变都与沙鼠利什曼原虫不同,对自然宿主大沙鼠的耳组织和远交系小鼠的致病力又与硕大利什曼原虫相异。作者认为,该地大沙鼠耳组织感染的利什曼原虫可能是一个新种(或新亚种),宜通过进一步的实验研究,来确定它分类上的地位。     

中国台湾孔头舌虫新种的发现及其致病特征

目的?摇探讨中国台湾孔头舌虫新种(Porocephalus taiwana sp. nov.)的形态与致病特征及新病种的病原学诊断方法。 方法 用患者稀便用粪便沉淀浓集法收集粪中若虫鉴定虫种，并结合临床资料作统计分析，以确定此新种所致疾病的临床特征。 结果 发现了舌形虫病的一种致病新种，即为台湾孔头舌虫，其所致的疾病称台湾孔头舌虫病。根据本例的发现，提出传统的内脏舌形虫病可分为2个亚型，成囊亚型和脱囊亚型。根据其病理学特征，本病例属于脱囊型内脏舌形虫病。 结论 描述了台湾孔头舌虫新种，其所致的台湾孔头舌虫病属于一种新型脱囊亚型性内脏舌形虫病。     

Adaptive mutations in the H5N1 polymerase complex

Adaptation of the viral polymerase to host factors plays an important role in interspecies transmission of H5N1 viruses. Several adaptive mutations have been identified that, in general, determine not only host range, but also pathogenicity and transmissibility of the virus. The available evidence indicates that most of these mutations are found in the PB2 subunit of the polymerase. Particularly prominent mutations are located in the C-terminal domain of PB2 involving the amino acid exchanges E627K and D701N. Both mutations, that are also responsible for the adaptation of other avian viruses to mammalian hosts, have been described in human H5N1 isolates. In animal models, it could be demonstrated that they enhance pathogenicity in mice and induce contact transmission in guinea pigs. Mutation E627K has also been identified as a determinant of air-borne H5N1 transmission in ferrets. We are only beginning to understand the underlying mechanisms at the molecular level. Thus, mutation D701N promotes importin-α mediated nuclear transport in mammalian cells. Mutation E627K also enhances the replication rate in an importin-α dependent fashion in mammalian cells, yet without affecting nuclear entry of PB2. Numerous other adaptive mutations, some of which compensate for the lack of PB2 E627K, have been observed in PB2 as well as in the polymerase subunit PB1, the nucleoprotein NP, and the nuclear export protein NEP (NS2).     

Single-cell approaches to investigate B cells and antibodies in autoimmune neurological disorders

Autoimmune neurological disorders, including neuromyelitis optica spectrum disorder, anti-N-methyl-D-aspartate receptor encephalitis, anti-MOG antibody-associated disorders, and myasthenia gravis, are clearly defined by the presence of autoantibodies against neurological antigens. Although these autoantibodies have been heavily studied for their biological activities, given the heterogeneity of polyclonal patient samples, the characteristics of a single antibody cannot be definitively assigned. This review details the findings of polyclonal serum and CSF studies and then explores the advances made by single-cell technologies to the field of antibody-mediated neurological disorders. High-resolution single-cell methods have revealed abnormalities in the tolerance mechanisms of several disorders and provided further insight into the B cells responsible for autoantibody production. Ultimately, several factors, including epitope specificity and binding affinity, finely regulate the pathogenic potential of an autoantibody, and a deeper appreciation of these factors may progress the development of targeted immunotherapies for patients.     

B型流感病毒冷适应株B/Yamagata/16/88反向遗传操作平台的搭建及BALB/c小鼠感染模型的建立

【摘要】 目的 本研究利用基因工程技术全基因合成B型流感病毒冷适应株B/Yamagata/16/88的8个基因节段,并利用反向遗传技术从体外拯救B型流感病毒冷适应株B/Yamagata/16/88,同时建立BALB/c小鼠感染模型,为下一步研究B型流感病毒致病机制、传播机制以及开发新型疫苗奠定基础。方法 通过基因合成和反向遗传技术体外拯救B型流感病毒冷适应株B/Yamagata/16/88。全基因组测序验证拯救病毒基因组序列与Genbank序列的一致性。将拯救病毒以105EID50的攻毒剂量人工感染BALB/c小鼠,通过体重变化、生存率、肺脏病毒复制等方面进行致病性分析,建立小鼠感染模型。结果 成功从体外拯救出B型流感病毒冷适应株B/Yamagata/16/88,命名为B-S9。全基因组测序结果表明,B-S9基因组序列与Genbank公布序列一致。B-S9能够人工感染BALB/c小鼠,但不致死,对BALB/c小鼠呈现低致病性; 攻毒后第3天,B-S9感染小鼠体重出现下降,攻毒后第8天,小鼠体重开始回升;攻毒后第3天和第6天,B-S9感染小鼠的肺脏内均能检测到病毒复制,且攻毒后第3天的小鼠肺脏病毒滴度比攻毒后第6天的小鼠肺脏滴度高132倍。结论 成功搭建B型流感病毒冷适应株B/Yamagata/16/88反向遗传操作平台,并建立BALB/c小鼠感染模型。目前国内外对B型流感病毒的研究还较少,该反向遗传操作平台的建立为B型流感病毒致病机制和传播机制的研究奠定了基础,同时也为包括B型流感病毒减毒活疫苗在内的新型疫苗的研制开辟了新途径。     

烟曲霉致病相关因子的研究进展

毒力因子是在病原体适应生存环境的过程中产生.烟曲霉毒力是多因素相关的,包括微小的孢子结构使之能够吸入到达宿主的肺泡,耐热特征,疏水性,快速的繁殖速度以及抵抗氧化应激反应的能力.此外,烟曲霉适应环境及代谢相关的蛋白、通路信号分子、脂类代谢产物、毒素等均可看作毒力因子.     

Lactobacillus fermentum,a pathogen in documented cholecystitis

INTRODUCTIONLactobacillus species are probiotics proven to exhibit various preventative as well as therapeutic properties. While lactobacillus species have been implicated in the formation of dental caries, endocarditis and bacteremia, their role as pathogens in cholecystitis has not been reported. We present a rare case of Lactobacillus fermentum working as a pathogen in cholecystitis.PRESENTATION OF CASEAn 81-year old male was admitted with right upper quadrant abdominal pain. His signs, symptoms, laboratory values and imaging were consistent with a diagnosis of cholecystitis with ascending cholangitis. In view of his co-morbidity and severe sepsis, the patient was treated non-operatively with antibiotics and cholecystostomy. L. fermentum, which was vancomycin resistant, was identified from the cholecystostomy aspirate and from anaerobic blood culture. The patient went into septic shock, developed multi-organ dysfunction syndrome and eventually died.DISCUSSIONCommensal bacteria such as L. fermentum are known to modulate immunity, reduce the pathogenicity of gastrointestinal organisms and play a therapeutic role in various disease processes. We isolated L. fermentum as a pathogen in a documented case of cholecystitis with ascending cholangitis.CONCLUSIONWhile the routine use lactobacillus species as a probiotic is supported in the literature, understanding its potential role as a pathogen may allow more judicious use of these bacteria and encourage research to elucidate the pathogenicity of lactobacillus species.