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71.
72.
In vivo study of the HC-TN strain of hepatitis C virus recovered from a patient with fulminant hepatitis: RNA transcripts of a molecular clone (pHC-TN) are infectious in chimpanzees but not in Huh7.5 cells 下载免费PDF全文
Sakai A Takikawa S Thimme R Meunier JC Spangenberg HC Govindarajan S Farci P Emerson SU Chisari FV Purcell RH Bukh J 《Journal of virology》2007,81(13):7208-7219
73.
Germinal centres (GCs) are specialised lymphoid microenvironments that form in secondary B-cell follicles upon exposure to T-dependent antigens. In the GC, clonal expansion, selection and differentiation of GC B cells result in the production of high-affinity plasma cells and memory B cells that provide protection against subsequent infection. The GC is carefully regulated to fulfil its critical role in defence against infection and to ensure that immunological tolerance is not broken in the process. The GC response can be controlled by a number of mechanisms, one of which is by forkhead box p3 expressing regulatory T (Treg) cells, a suppressive population of CD4+ T cells. A specialised subset of Treg cells – follicular regulatory T (Tfr) cells – form after immunisation and are able to access the GC, where they control the size and output of the response. Our knowledge of Treg cell control of the GC is expanding. In this review we will discuss recent advances in the field, with a particular emphasis on the differentiation and function of Tfr cells in the GC. 相似文献
74.
Mosi L Mutoji NK Basile FA Donnell R Jackson KL Spangenberg T Kishi Y Ennis DG Small PL 《Microbes and infection / Institut Pasteur》2012,14(9):719-729
Mycobacterium ulcerans causes Buruli ulcer in humans, a progressive ulcerative epidermal lesion due to the mycolactone toxin produced by the bacterium. Molecular analysis of M. ulcerans reveals it is closely related to Mycobacterium marinum, a pathogen of both fish and man. Molecular evidence from diagnostic PCR assays for the insertion sequence IS2404 suggests an association of M. ulcerans with fish. However, fish infections by M. ulcerans have not been well documented and IS2404 has been found in other mycobacteria. We have thus, employed two experimental approaches to test for M. ulcerans in fish. We show here for the first time that M. ulcerans with or without the toxin does not mount acute or chronic infections in Japanese Medaka "Oryzias latipes" even at high doses. Moreover, M. ulcerans-infected medaka do not exhibit any visible signs of infection nor disease and the bacteria do not appear to replicate over time. In contrast, similar high doses of the wild-type M. marinum or a mycolactone-producing M. marinum "DL" strain are able to mount an acute disease with mortality in medaka. Although these results would suggest that M. ulcerans does not mount infections in fish we have evidence that CLC macrophages from goldfish are susceptible to mycolactones. 相似文献
75.
Macrophysiology is defined as the study of variation in physiological traits-including physiological trait flexibility-over large geographical and temporal scales, and the ecological implications of this variation. A classic example of a macrophysiological trend is the one emerging from the climatic variability hypothesis, which states that as the range of climatic fluctuation experienced by terrestrial animals increases with latitude, individuals at higher latitudes should be more plastic than individuals inhabiting lower latitudes. In this context, we evaluate the correlation between absolute metabolic scope during cold exposure (an instantaneous measure of metabolic flexibility) and different geographic and climatic variables for 48 rodent species. Conventional and phylogenetic informed analyses indicated a positive correlation between metabolic scope and geographic latitude. These findings, together with previous reports on latitudinal pattern in phenotypic flexibility, suggest that an increase in physiological flexibility with latitude may hold for many phenotypic traits. 相似文献
76.
Bukh J Thimme R Meunier JC Faulk K Spangenberg HC Chang KM Satterfield W Chisari FV Purcell RH 《Journal of virology》2008,82(16):8183-8195
Protective immunity after resolved hepatitis C virus (HCV) infection has been reported. However, the breadth of this immunity has remained controversial, and the role of neutralizing antibodies has not been well-defined. In the present study, two chimpanzees (CH96A008 and CH1494) with resolved monoclonal H77C (genotype 1a) infection were rechallenged with low-dose homologous H77C virus about 12 months after viral clearance; CH96A008 became persistently infected, and CH1494 had transient viremia lasting 2 weeks. CH1494 was subsequently either partially or completely protected following five homologous rechallenges with monoclonal H77C or polyclonal H77 and after six heterologous rechallenges with HC-J4 (genotype 1b) or HC-J6 (genotype 2a) viruses. Subsequently, a final challenge with H77C resulted in persistent HCV infection. In both chimpanzees, serum neutralizing antibodies against retroviral pseudoparticles bearing the H77C envelope proteins were not detected during the initial infection or during rechallenge. However, anamnestic cellular immune responses developed during the initial homologous rechallenge, in particular in CH96A008, which developed a persistent infection. Polyprotein sequences of viruses recovered from CH1494 after the two homologous rechallenges that resulted in transient viremia were identical with the H77C virus. In contrast, the polyprotein sequences of viruses recovered from both chimpanzees after homologous rechallenge resulting in persistent infection had numerous changes. These findings have important implications for our understanding of immunity against HCV; even in the best-case scenario with autologous rechallenge, low-level viral persistence was seen in the presence of primed T-cell responses. 相似文献
77.
Gene expression in diplosporous and sexual Eragrostis curvula genotypes with differing ploidy levels
Cervigni GD Paniego N Pessino S Selva JP Díaz M Spangenberg G Echenique V 《Plant molecular biology》2008,67(1-2):11-23
The molecular nature of gene expression during the initiation and progress of diplosporous apomixis is still unknown. Moreover,
the basis of the close correlation between diplospory and polyploidy is not clarified yet. A comparative expression analysis
was performed based on expressed sequence tags (ESTs) sequencing and differential display in an Eragrostis curvula diplosporous tetraploid genotype (T, 4x apo), a sexual diploid derivative obtained from tissue culture (D, 2x sex) and an
artificial sexual tetraploid obtained from the diploid seeds after colchicine treatment (C, 4x sex). From a total of 8,884
unigenes sequenced from inflorescence-derived libraries, 112 (1.26%) showed significant differential expression in individuals
with different ploidy level and/or variable reproductive mode. Independent comparisons between plants with different reproductive
mode (same ploidy) or different ploidy level (same reproductive mode) allowed the identification of genes modulated in response
to diplosporous development or polyploidization, respectively. Surprisingly, a group of genes (Group 3) were differentially
expressed or silenced only in the 4x sex plant, presenting similar levels of expression in the 4x apo and the 2x sex genotypes.
A group of randomly selected differential genes was validated by QR-PCR. Differential display analysis showed that in general
the 4x apo and 4x sex expression profiles were more related and different from the 2x sex one, but confirmed the existence
of Group 3-type genes, in both inflorescences and leaves. The possible biological significance for the occurrence of this
particular group of genes is discussed. In silico mapping onto the rice genome was used to identify candidates mapping to
the region syntenic to the diplospory locus.
Gerardo D. L. Cervigni, Norma Paniego and Silvina Pessino contributed equally to the work. 相似文献
78.
Hand ML Ponting RC Drayton MC Lawless KA Cogan NO Charles Brummer E Sawbridge TI Spangenberg GC Smith KF Forster JW 《Molecular genetics and genomics : MGG》2008,280(4):293-304
The combination of homologous, homoeologous and paralogous classes of sequence variation presents major challenges for SNP discovery in outbreeding allopolyploid species. Previous in vitro gene-associated SNP discovery studies in the allotetraploid forage legume white clover (Trifolium repens L.) were vulnerable to such effects, leading to prohibitive levels of attrition during SNP validation. Identification of T. occidentale and T. pallescens as the putative diploid progenitors of white clover has permitted discrimination of the different sequence variant categories. Amplicons from selected abiotic stress tolerance-related genes were obtained using mapping family parents and individuals from each diploid species. Following cloning, progenitor comparison allowed tentative assignment of individual haplotypes to one or other sub-genome, as well as to gene copies within sub-genomes. A high degree of coincidence and identity between SNPs and HSVs was observed. Close similarity was observed between the genome of T. occidentale and one white clover sub-genome, but the affinity between T. pallescens and the other sub-genome was weaker, suggesting that a currently uncharacterised taxon may be the true second progenitor. Selected validated SNPs were attributed to individual sub-genomes by assignment to and naming of homoeologous linkage groups, providing the basis for improved genetic trait-dissection studies. The approach described in this study is broadly applicable to a range of allopolyploid taxa of equivocal ancestry. 相似文献
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