Rickettsial Endosymbionts of Ticks

Rickettsiae are widely known to be human bacterial pathogens transmitted by blood-sucking ectoparasites, such as ticks, fleas, and lice. However, most rickettsial species are nonpathogenic endosymbionts with various groups of organisms, such as arthropods, protists, and other eukaryotes. While attention has been given to rickettsial endosymbionts of insects, rickettsial endosymbionts of ticks have been less well studied. Tick hosts are found across the phylogeny of Rickettsiae; hence, the tick was the most probable ancestral host of Rickettsiae associated with arthropods. Here, we focus on rickettsial endosymbionts of ticks, describing their role in association with ticks and comparing them to tick-borne vertebrate pathogens

Lidský genom: kam kráčí současný výzkum?

Uveřejnění pilotní sekvence lidského genomu (v roce 2001) a "úplné" dokončení jeho sekvence (v roce 2004) otevřelo problém interpretace ohromného množství získaných dat. Nutno podotknout, že sekvenci lidského genomu stále neznáme úplně dokonale, stále je v genomu přes 300 "mezer", tedy míst, pro která přesnou sekvenci neznáme, a navíc je v "definitivní" verzi sekvence více než deset tisíc jednonukleových chyb. Žádné lidské poznání však není dokonalé a s přibývajícími sekvenačními projekty se "definitivní" sekvence stále zpřesňuje

First evidence of high-molecular-weight bacteriocin (tailocin) produced by Antarctic Pseudomonas spp.

Cold-adapted soil ecosystems represent dynamic communities varying in a structure, microbial abundance and metabolic activity. To antagonize competitors, soil bacteria produce a variety of inhibitory agents. We tested production of antimicrobials in Pseudomonas spp. isolated in James Ross Island, Antarctica, and performed transmission electron microscopic analyses of selected high-molecular-weight bacteriocin particles. The dimensions of R-tailocins produced by Pseudomonas sp. P2422 were 168 ± 2.0nm (length) and 16 ± 0.8nm (width) thus representing one of the largest tailocins secreted by Pseudomonas spp. To our knowledge, this is the first evidence of tailocin production by bacteria originated from polar regions

Pseudomonas prosekii isolated in Antarctica inhibits plantpathogenic strains of Pseudomonas viridiflava and Pseudomonas fluorescens

Pseudomonas-caused plant diseases are present worldwide and affect most of the major lineages of higher plants which, as a consequence, may result in significant economic losses. Despite the use of bacteriocins produced by rhizosphere and soil bacteria has been nowadays considered as novel crop protection approach, antagonistic interactions of cold-adapted isolates toward agriculturally important phytopathogenic bacteria have not been studied yet. In this study, we tested inhibition activity of Antarctic Pseudomonas spp. against phytopathogenic pseudomonads. Four Antarctic stains (P. prosekii CCM 8878, CCM 8879, and CCM 8881 and Pseudomonas sp. CCM 8880) inhibited several phytopathogenic strains of P. viridiflava and P. fluorescens. Based on inhibition zone character and previous genome research we suggest that L-pyocin activity was responsible for this effect against P. viridiflava strains and that tailocin inhibited P. fluorescens isolate

Genetic diversity in Treponema pallidum: Implications for pathogenesis, evolution and molecular diagnostics of syphilis and yaws

AbstractPathogenic uncultivable treponemes, similar to syphilis-causing Treponema pallidum subspecies pallidum, include T. pallidum ssp. pertenue, T. pallidum ssp. endemicum and Treponema carateum, which cause yaws, bejel and pinta, respectively. Genetic analyses of these pathogens revealed striking similarity among these bacteria and also a high degree of similarity to the rabbit pathogen, Treponema paraluiscuniculi, a treponeme not infectious to humans. Genome comparisons between pallidum and non-pallidum treponemes revealed genes with potential involvement in human infectivity, whereas comparisons between pallidum and pertenue treponemes identified genes possibly involved in the high invasivity of syphilis treponemes. Genetic variability within syphilis strains is considered as the basis of syphilis molecular epidemiology with potential to detect more virulent strains, whereas genetic variability within a single strain is related to its ability to elude the immune system of the host. Genome analyses also shed light on treponemal evolution and on chromosomal targets for molecular diagnostics of treponemal infections

Human extraintestinal pathogenic Escherichia coli strains differ in prevalence of virulence factors, phylogroups, and bacteriocin determinants

Table S4. Differences in the distribution of virulence factors, E. coli phylogroups, bacteriocin production, and bacteriocin determinants between subgroups of ExPEC strains and fecal strains. (XLSX 14 kb

Isolation of human pathogen Escherichia albertii from faeces of seals (Leptonychotes weddelli) in James Ross Island, Antarctica

A set of nine gram-negative fermenting rods biochemically identified as Escherichia coli was isolated from faeces of seals. These bacteria were characterized by phenotypic classification, 16S rDNA sequence analyses, automated ribotyping, study of whole-cell protein profiles by SDS-PAGE and finally by bacteriocin production. The results of our polyphasic taxonomic study supported the recognition of P4652, P4653 and P4740 isolates as true members of Escherichia albertii species – probably a major enteric human pathogen. To our best knowledge, this is the first evidence showing that E. albertii produces bacteriocin, colicin D. Obtained data unambiguously showed incon-venience of commercial identification systems to distinguish both Escherichia species due to missing data of E. albertii in the commercial databases. The results of Escherichia isolates taxonomy suggest seals as a novel source of human and animal pathogen,E. albertii in the Antarctic region

A public database for the new MLST scheme for Treponema pallidum subsp. pallidum: surveillance and epidemiology of the causative agent of syphilis

Treponema pallidum subsp. pallidum is the causative agent of syphilis, a sexually transmitted disease with worldwide prevalence. Several different molecular typing schemes are currently available for this pathogen. To enable population biology studies of the syphilis agent and for epidemiological surveillance at the global scale, a harmonized typing tool needs to be introduced. Recently, we published a new multi-locus sequence typing (MLST) with the potential to significantly enhance the epidemiological data in several aspects (e.g., distinguishing genetically different clades of syphilis, subtyping inside these clades, and finally, distinguishing different subspecies of non-cultivable pathogenic treponemes). In this short report, we introduce the PubMLST database for treponemal DNA data storage and for assignments of allelic profiles and sequencing types. Moreover, we have summarized epidemiological data of all treponemal strains (n = 358) with available DNA sequences in typing loci and found several association between genetic groups and characteristics of patients. This study proposes the establishment of a single MLST of T. p. pallidum and encourages researchers and public health communities to use this PubMLST database as a universal tool for molecular typing studies of the syphilis pathogen

Treponema pallidum, the syphilis spirochete: making a living as a stealth pathogen

The past two decades have seen a worldwide resurgence in infections caused by Treponema pallidum subsp. pallidum, the syphilis spirochete. The well-recognized capacity of the syphilis spirochete for early dissemination and immune evasion has earned it the designation 'the stealth pathogen'. Despite the many hurdles to studying syphilis pathogenesis, most notably the inability to culture and to genetically manipulate T. pallidum, in recent years, considerable progress has been made in elucidating the structural, physiological, and regulatory facets of T. pallidum pathogenicity. In this Review, we integrate this eclectic body of information to garner fresh insights into the highly successful parasitic lifestyles of the syphilis spirochete and related pathogenic treponemes

Patients With Common Variable Immunodeficiency (CVID) Show Higher Gut Bacterial Diversity and Levels of Low-Abundance Genes Than the Healthy Housemates

Common variable immunodeficiency (CVID) is a clinically and genetically heterogeneous disorder with inadequate antibody responses and low levels of immunoglobulins including IgA that is involved in the maintenance of the intestinal homeostasis. In this study, we analyzed the taxonomical and functional metagenome of the fecal microbiota and stool metabolome in a cohort of six CVID patients without gastroenterological symptomatology and their healthy housemates. The fecal microbiome of CVID patients contained higher numbers of bacterial species and altered abundance of thirty-four species. Hungatella hathewayi was frequent in CVID microbiome and absent in controls. Moreover, the CVID metagenome was enriched for low-abundance genes likely encoding nonessential functions, such as bacterial motility and metabolism of aromatic compounds. Metabolomics revealed dysregulation in several metabolic pathways, mostly associated with decreased levels of adenosine in CVID patients. Identified features have been consistently associated with CVID diagnosis across the patients with various immunological characteristics, length of treatment, and age. Taken together, this initial study revealed expansion of bacterial diversity in the host immunodeficient conditions and suggested several bacterial species and metabolites, which have potential to be diagnostic and/or prognostic CVID markers in the future