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排序方式: 共有170条查询结果,搜索用时 703 毫秒
21.
Kai Zhang Jun He Claudio Catalano Youzhong Guo Jun Liu Chunhao Li 《Molecular microbiology》2020,113(6):1122-1139
The Lyme disease bacterium Borrelia burgdorferi has 7–11 periplasmic flagella (PF) that arise from the cell poles and extend toward the midcell as a flat-ribbon, which is distinct from other bacteria. FlhF, a signal recognition particle (SRP)-like GTPase, has been found to regulate the flagellar number and polarity; however, its role in B. burgdorferi remains unknown. B. burgdorferi has an FlhF homolog (BB0270). Structural and biochemical analyses show that BB0270 has a similar structure and enzymatic activity as its counterparts from other bacteria. Genetics and cryo-electron tomography studies reveal that deletion of BB0270 leads to mutant cells that have less PF (4 ± 2 PF per cell tip) and fail to form a flat-ribbon, indicative of a role of BB0270 in the control of PF number and configuration. Mechanistically, we demonstrate that BB0270 localizes at the cell poles and controls the number and position of PF via regulating the flagellar protein stability and the polar localization of the MS-ring protein FliF. Our study not only provides the detailed characterizations of BB0270 and its profound impacts on flagellar assembly, morphology and motility in B. burgdorferi, but also unveils mechanistic insights into how spirochetes control their unique flagellar patterns. 相似文献
22.
Roberto Cevenini Vittorio Sambri Francesca Massaria Michelangelo La Placa Emiliana Brocchi Franco De Simone 《FEMS microbiology letters》1992,90(2):147-152
Murine monoclonal antibodies (mAbs) were obtained against the outer-surface-protein OspA and OspB and against the 41-kDa flagellar antigen of Borrelia burgdorferi. The specificity of mAb was determined by the Western blotting technique and the surface association of the antigens was inferred by immunofluorescence of living bacteria. In an in vitro assay in the presence of complement, two mAbs reactive with the Ospa were able to kill borreliae, whereas several mAbs reactive with the OspA as well as with the 41-kDa flagellar protein were not. 相似文献
23.
Hisanori Konishi Muhammad Golam Morshed Hisaji Akitomi Teruko Nakazawa 《Microbiology and immunology》1993,37(3):229-232
Borrelia duttonii strain 406 K, a causative agent of relapsing fever, could not be cultivated in vitro in currently available media for borreliae. We have developed an in vitro cultivation system by using SflEp cell cultures. The average increases of the number of borreliae, when inoculated with 1.0 × 105 organisms per ml from infected mice, were 23-fold and 150-fold in the primary culture and the 3rd subculture, respectively. Even a single borrelia could propagate in this cultivation system. This system will be useful for immunological and physiological studies on uncultivable Borrelia strains. 相似文献
24.
Abstract An Escherichia coli clone containing recombinant plasmid C19 was identified from a Treponema pallidum genomic DNA library by in situ immunoassay. E. coli maxicells containing pC19 synthesized a treponemal protein doublet of 39.2 and 38.2 kDa, designated TpN38(b). Pulse-chase and protein processing studies showed that TpN38(b) is synthesized with a cleavable amino-terminal signal peptide. A 2.0-kb fragment of pC19 containing the tpn38(b) gene was subcloned and sequenced. The tpn38(b) gene is 1029 nucleotides long and encodes a protein of 343 amino acids with a calculated molecular mass of 37.9 kDa. The deduced amino acid sequence of TpN38(b) has homology with the T. pallidum TpN35 lipoprotein and the Borrelia burgdorferi BmpA, BmpB, BmpC, and BmpD proteins. 相似文献
25.
Borrelia burgdorferi surface‐located Lmp1 protein processed into region‐specific polypeptides that are critical for microbial persistence
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One of the Borrelia burgdorferi virulence determinants, annotated as Lmp1, is a surface‐exposed, conserved, and potential multi‐domain protein involved in various functions in spirochete infectivity. Lmp1 contributes to host–pathogen interactions and evasion of host adaptive immunity by spirochetes. Here, we show that in diverse B. burgdorferi species, Lmp1 exists as distinct, region‐specific, and lower molecular mass polypeptides encompassing 1 or more domains, including independent N‐terminal and middle regions and a combined middle and C‐terminal region. These polypeptides originate from complex posttranslational maturation events, partly supported by a periplasmic serine protease termed as BbHtrA. Although spirochete persistence in mice is independently supported by domain‐specific Lmp1 polypeptides, transmission of B. burgdorferi from ticks to mammals requires essential contributions from both N‐terminal and middle regions. Interference with the functions of Lmp1 domains or their complex posttranslational maturation events may aid in development of novel therapeutic strategies to combat infection and transmission of pathogens. 相似文献
26.
Lars Eisen Rebecca J. Eisen Jeomhee Mun Daniel J. Salkeld Robert S. Lane 《Journal of vector ecology》2009,34(1):81-91
This study was undertaken to determine which rodent species serve as primary reservoirs for the Lyme disease spirochete Borrelia burgdorferi in commonly occurring woodland types in inland areas of northwestern California, and to examine whether chaparral or grassland serve as source habitats for dispersal of B. burgdorferi‐ or B. bissettii‐infected rodents into adjacent woodlands. The western gray squirrel (Sciurus griseus) was commonly infected with B. burgdorferi in oak woodlands, whereas examination of 30 dusky‐footed woodrats (Neotoma fuscipes) and 280 Peromyscus spp. mice from 13 widely‐spaced Mendocino County woodlands during 2002 and 2003 yielded only one infected woodrat and one infected deer mouse (P. maniculatus). These data suggest that western gray squirrels account for the majority of production by rodents of fed Ixodes pacificus larvae infected with B. burgdorferi in the woodlands sampled. Infections with B. burgdorferi also were rare in woodrats (0/47, 0/3) and mice (3/66, 1/6) captured in chaparral and grassland, respectively, and therefore these habitats are unlikely sources for dispersal of this spirochete into adjacent woodlands. On the other hand, B. bissettii was commonly detected in both woodrats (22/47) and mice (15/66) in chaparral. We conclude that the data from this and previous studies in northwestern California are suggestive of a pattern where inland oak‐woodland habitats harbor a B. burgdorferi transmission cycle driven primarily by I. pacificus and western gray squirrels, whereas chaparral habitats contain a B. bissettii transmission cycle perpetuated largely by I. spinipalpis, woodrats, and Peromyscus mice. The dominant role of western gray squirrels as reservoirs of B. burgdorferi in certain woodlands offers intriguing opportunities for preventing Lyme disease by targeting these animals by means of either host‐targeted acaricides or oral vaccination against B. burgdorferi. 相似文献
27.
When taking their blood meal on the mammalian host, ticks transfer a multitude of different proteins from their saliva into
the host. Some of these proteins are hijacked by pathogens for their own purposes. Borrelia burgdorferi, the Lyme disease agent, is critically dependent on the presence of the tick protein Salp15 when infecting the host. Similarly,
Anaplasma phagocytophilum, which causes anaplasmosis, needs Salp16, a homologue of Salp15, to get transferred from the host into the tick. Here we
analyzed whether adaptive evolution has shaped the Salp15 protein family. Using site-specific estimates of KA/KS ratios, we identified different positions within the Salp15 protein family which have undergone a phase of positive selection.
Additionally, we analyzed the B. burgdorferi protein interacting with Salp15, OspC. Again, sites showing signs of positive selection were identified, although they are
more likely a result of the antigenic features of OspC than of the influence of Salp15. The identification of probably functionally
relevant sites in the Salp15 family might direct the detailed experimental analysis of their interaction with human and bacterial
proteins.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
28.
Maria A. Diuk‐Wasser Gwenaël Vourc'h Paul Cislo Anne Gatewood Hoen Forrest Melton Sarah A. Hamer Michelle Rowland Roberto Cortinas Graham J. Hickling Jean I. Tsao Alan G. Barbour Uriel Kitron Joseph Piesman Durland Fish 《Global Ecology and Biogeography》2010,19(4):504-514
Aim Ixodes scapularis is the most important vector of human tick‐borne pathogens in the United States, which include the agents of Lyme disease, human babesiosis and human anaplasmosis, among others. The density of host‐seeking I. scapularis nymphs is an important component of human risk for acquiring Borrelia burgdorferi, the aetiological agent of Lyme disease. In this study we used climate and field sampling data to generate a predictive map of the density of host‐seeking I. scapularis nymphs that can be used by the public, physicians and public health agencies to assist with the diagnosis and reporting of disease, and to better target disease prevention and control efforts. Location Eastern United States of America. Methods We sampled host‐seeking I. scapularis nymphs in 304 locations uniformly distributed east of the 100th meridian between 2004 and 2006. Between May and September, 1000 m2 were drag sampled three to six times per site. We developed a zero‐inflated negative binomial model to predict the density of host‐seeking I. scapularis nymphs based on altitude, interpolated weather station and remotely sensed data. Results Variables that had the strongest relationship with nymphal density were altitude, monthly mean vapour pressure deficit and spatial autocorrelation. Forest fragmentation and soil texture were not predictive. The best‐fit model identified two main foci – the north‐east and upper Midwest – and predicted the presence and absence of I. scapularis nymphs with 82% accuracy, with 89% sensitivity and 82% specificity. Areas of concordance and discordance with previous studies were discussed. Areas with high predicted but low observed densities of host‐seeking nymphs were identified as potential expansion fronts. Main conclusions This model is unique in its extensive and unbiased field sampling effort, allowing for an accurate delineation of the density of host‐seeking I. scapularis nymphs, an important component of human risk of infection for B. burgdorferi and other I. scapularis‐borne pathogens. 相似文献
29.
Infection with the Lyme disease pathogen suppresses innate immunity in mice with diet‐induced obesity
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Nataliya Zlotnikov Ashkan Javid Mijhgan Ahmed Azad Eshghi Tian Tian Tang Anoop Arya Anil Bansal Fatima Matar Maitry Parikh Rhodaba Ebady Adeline Koh Nupur Gupta Peng Song Yang Zhang Susan Newbigging Gary P. Wormser Ira Schwartz Robert Inman Michael Glogauer Tara J. Moriarty 《Cellular microbiology》2017,19(5)
Obesity is a major global public health concern. Immune responses implicated in obesity also control certain infections. We investigated the effects of high‐fat diet‐induced obesity (DIO) on infection with the Lyme disease bacterium Borrelia burgdorferi in mice. DIO was associated with systemic suppression of neutrophil‐ and macrophage‐based innate immune responses. These included bacterial uptake and cytokine production, and systemic, progressive impairment of bacterial clearance, and increased carditis severity. B. burgdorferi‐infected mice fed normal diet also gained weight at the same rate as uninfected mice fed high‐fat diet, toll‐like receptor 4 deficiency rescued bacterial clearance defects, which greater in female than male mice, and killing of an unrelated bacterium (Escherichia coli) by bone marrow‐derived macrophages from obese, B. burgdorferi‐infected mice was also affected. Importantly, innate immune suppression increased with infection duration and depended on cooperative and synergistic interactions between DIO and B. burgdorferi infection. Thus, obesity and B. burgdorferi infection cooperatively and progressively suppressed innate immunity in mice. 相似文献
30.
Detection of Borrelia burgdorferi and Anaplasma phagocytophilum in the black‐legged tick,Ixodes scapularis,within southwestern Pennsylvania
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Prevalence studies of Borrelia burgdorferi and Anaplasma phagocytophilum have been rare for ticks from southwestern Pennsylvania. We collected 325 Ixodes scapularis ticks between 2011 and 2012 from four counties in southwestern Pennsylvania. We tested for the presence of Borrelia burgdorferi and Anaplasma phagocytophilum using PCR. Of the ticks collected from Pennsylvania, B. burgdorferi (causative agent of Lyme disease) was present in 114/325 (35%) and Anaplasma phagocytophilum (causative agent of Human Granulocytic Anaplasmosis) was present in 48/325 (15%) as determined by PCR analysis. 相似文献