Showing papers by "Bundeswehr Institute of Microbiology published in 2011"

Copper toxicity and the origin of bacterial resistance—new insights and applications

Abstract: The bioavailability of different metals has likely changed over the course of Earth's history. Based on geochemical models, copper became much more bioavailable with the advent of an oxidizing atmosphere. This posed both a challenge and an opportunity for the organisms at that time. Specifically, copper resistance mechanisms were required first and to do this Bacteria appear to have modified already existing protein structures. Later, Cu-utilizing proteins evolved and continue to be used sparingly, at least relative to later evolving Eukarya, by Bacteria but with significant biogeochemical consequences. Copper is a strong soft metal that can attack intracellular iron–sulfur centers of various proteins under primarily anoxic conditions. In oxic conditions, copper can catalyze a Fenton-like reaction that may cause lipid peroxidation and protein damage. The inherent ability of copper to inflict damage upon multiple cellular functions has been harnessed by macrophages and perhaps amoeba to kill and later digest bacteria and other microorganisms. Notably, these organisms, unlike Bacteria, most likely evolved after increases in copper availability, implying that Eukarya utilized their own trafficking and resistance mechanisms, in addition to the natural toxicity of copper, as leverage in interactions with Bacteria. In an “arms race,” some pathogenic bacteria have evolved new mechanisms for copper resistance, which is relevant given renewed interest in the use of copper surfaces due to their antimicrobial properties.

Chasing Jenner's Vaccine: Revisiting Cowpox Virus Classification

Abstract: Cowpox virus (CPXV) is described as the source of the first vaccine used to prevent the onset and spread of an infectious disease. It is one of the earliest described members of the genus Orthopoxvirus, which includes the viruses that cause smallpox and monkeypox in humans. Both the historic and current literature describe “cowpox” as a disease with a single etiologic agent. Genotypic data presented herein indicate that CPXV is not a single species, but a composite of several (up to 5) species that can infect cows, humans, and other animals. The practice of naming agents after the host in which the resultant disease manifests obfuscates the true taxonomic relationships of “cowpox” isolates. These data support the elevation of as many as four new species within the traditional “cowpox” group and suggest that both wild and modern vaccine strains of Vaccinia virus are most closely related to CPXV of continental Europe rather than the United Kingdom, the homeland of the vaccine.

Diseases and causes of death in European bats: dynamics in disease susceptibility and infection rates

Abstract: Background: Bats receive increasing attention in infectious disease studies, because of their well recognized status as reservoir species for various infectious agents. This is even more important, as bats with their capability of long distance dispersal and complex social structures are unique in the way microbes could be spread by these mammalian species. Nevertheless, infection studies in bats are predominantly limited to the identification of specific pathogens presenting a potential health threat to humans. But the impact of infectious agents on the individual host and their importance on bat mortality is largely unknown and has been neglected in most studies published to date. Methodology/Principal Findings: Between 2002 and 2009, 486 deceased bats of 19 European species (family Vespertilionidae) were collected in different geographic regions in Germany. Most animals represented individual cases that have been incidentally found close to roosting sites or near human habitation in urban and urban-like environments. The bat carcasses were subjected to a post-mortem examination and investigated histo-pathologically, bacteriologically and virologically. Trauma and disease represented the most important causes of death in these bats. Comparative analysis of pathological findings and microbiological results show that microbial agents indeed have an impact on bats succumbing to infectious diseases, with fatal bacterial, viral and parasitic infections found in at least 12% of the bats investigated. Conclusions/Significance: Our data demonstrate the importance of diseases and infectious agents as cause of death in European bat species. The clear seasonal and individual variations in disease prevalence and infection rates indicate that maternity colonies are more susceptible to infectious agents, underlining the possible important role of host physiology, immunity and roosting behavior as risk factors for infection of bats.

Tick-borne encephalitis virus in dogs - is this an issue?

Abstract: The last review on Tick-borne encephalitis (TBE) in dogs was published almost ten years ago Since then, this zoonotic tick-borne arbovirus has been geographically spreading and emerging in many regions in Eurasia and continues to do so Dogs become readily infected with TBE virus but they are accidental hosts not capable to further spread the virus They seroconvert upon infection but they seem to be much more resistant to the clinical disease than humans Apart from their use as sentinels in endemic areas, however, an increasing number of case reports appeared during the last decade thus mirroring the rising public health concerns Owing to the increased mobility of people travelling to endemic areas with their companion dogs, this consequently leads to problems in recognizing and diagnosing this severe infection in a yet non-endemic area, simply because the veterinarians are not considering TBE This situation warrants an update on the epidemiology, clinical presentation and possible preventions of TBE in the dog

Rickettsia spp. in wild small mammals in Lower Bavaria, South-Eastern Germany.

Abstract: So far, data on the natural cycle of rickettsiae of the tick-borne spotted fever group (SFG) in Central Europe are barely available. Some studies showed the occurrence of different Rickett...

Using Remote Sensing to Map the Risk of Human Monkeypox Virus in the Congo Basin

Abstract: Although the incidence of human monkeypox has greatly increased in Central Africa over the last decade, resources for surveillance remain extremely limited. We conducted a geospatial analysis using existing data to better inform future surveillance efforts. Using active surveillance data collected between 2005 and 2007, we identified locations in Sankuru district, Democratic Republic of Congo (DRC) where there have been one or more cases of human monkeypox. To assess what taxa constitute the main reservoirs of monkeypox, we tested whether human cases were associated with (i) rope squirrels (Funisciurus sp.), which were implicated in monkeypox outbreaks elsewhere in the DRC in the 1980s, or (ii) terrestrial rodents in the genera Cricetomys and Graphiurus, which are believed to be monkeypox reservoirs in West Africa. Results suggest that the best predictors of human monkeypox cases are proximity to dense forests and associated habitat preferred by rope squirrels. The risk of contracting monkeypox is significantly greater near sites predicted to be habitable for

Diseases in free-ranging bats from Germany

Abstract: Background: The emergence of important viral diseases and their potential threat to humans has increased the interest in bats as potential reservoir species. Whereas the majority of studies determined the occurrence of specific zoonotic agents in chiropteran species, little is known about actual bat pathogens and impacts of disease on bat mortality. Combined pathological and microbiological investigations in free-ranging bats are sparse and often limited by small sample sizes. In the present study about 500 deceased bats of 19 European species (family Vespertilionidae) were subjected to a post-mortem examination followed by histo-pathological and bacteriological investigations. The bat carcasses originated from different geographical regions in Germany and were collected by bat researchers and bat rehabilitation centers. Results: Pathological examination revealed inflammatory lesions in more than half of the investigated bats. Lung was the predominantly affected organ (40%) irrespective of bat species, sex and age. To a lesser extent noninflammatory organ tissue changes were observed. Comparative analysis of histo-pathology and bacteriology results identified 22 different bacterial species that were clearly associated with pathological lesions. Besides disease-related mortality, traumatic injuries represented an additional major cause of death. Here, attacks by domestic cats accounted for almost a half of these cases. Conclusions: The present study shows that free-ranging bats not only serve as a reservoir of infectious agents, they are also vulnerable to various infectious diseases. Some of these microbial agents have zoonotic potential, but there is no evidence that European bats would pose a higher health hazard risk to humans in comparison to other wildlife.

Contributions of Five Secondary Metal Uptake Systems to Metal Homeostasis of Cupriavidus metallidurans CH34

Abstract: Cupriavidus metallidurans is adapted to high concentrations of transition metal cations and is a model system for studying metal homeostasis in difficult environments. The elemental composition of C. metallidurans cells cultivated under various conditions was determined, revealing the ability of the bacterium to shield homeostasis of one essential metal from the toxic action of another. The contribution of metal uptake systems to this ability was studied. C. metallidurans contains three CorA members of the metal inorganic transport (MIT) protein family of putative magnesium uptake systems, ZupT of the ZRT/IRT protein, or ZIP, family, and PitA, which imports metal phosphate complexes. Expression of the genes for all these transporters was regulated by zinc availability, as shown by reporter gene fusions. While expression of zupT was upregulated under conditions of zinc starvation, expression of the other genes was downregulated at high zinc concentrations. Only corA(1) expression was influenced by magnesium starvation. Deletion mutants were constructed to characterize the contribution of each system to transition metal import. This identified ZupT as the main zinc uptake system under conditions of low zinc availability, CorA(1) as the main secondary magnesium uptake system, and CorA(2) and CorA(3) as backup systems for metal cation import. PitA may function as a cation-phosphate uptake system, the main supplier of divalent metal cations and phosphate in phosphate-rich environments. Thus, metal homeostasis in C. metallidurans is achieved by highly redundant metal uptake systems, which have only minimal cation selectivity and are in combination with efflux systems that "worry later" about surplus cations.

Tick-borne lymphadenopathy (TIBOLA) acquired in Southwestern Germany

Abstract: Tick-borne lymphadenopathy (TIBOLA) was first described in 1997 in a patient in France. The causative agent, Rickettsia slovaca, is transmitted by Dermacentor ticks. In southwestern Germany we encountered a patient with a tick bite at the dorsal scalp that resulted in an eschar and nuchal lymphadenopathy. Additionally, fever, malaise as well as elevated inflammatory markers and transaminases occurred. The characteristic clinical picture along with positive antibody testing for rickettsiae of the tick-borne spotted fever group strongly suggest the diagnosis TIBOLA. Human rickettsioses are emerging infections. Clinicians should be aware of TIBOLA as a newly described rickettsial disease. As in our case, TIBOLA may be encountered in regions/countries where R. slovaca and Dermacentor ticks are prevalent but autochthonous acquisition was not described before.

Phylogenetic analysis of Puumala virus subtype Bavaria, characterization and diagnostic use of its recombinant nucleocapsid protein.

Abstract: Puumala virus (PUUV) is the predominant hantavirus species in Germany causing large numbers of mild to moderate cases of haemorrhagic fever with renal syndrome (HFRS). During an outbreak in South-East Germany in 2004 a novel PUUV subtype designated Bavaria was identified as the causative agent of HFRS in humans [1]. Here we present a molecular characterization of this PUUV strain by investigating novel partial and almost entire nucleocapsid (N) protein-encoding small (S-) segment sequences and partial medium (M-) segment sequences from bank voles (Myodes glareolus) trapped in Lower Bavaria during 2004 and 2005. Phylogenetic analyses confirmed their classification as subtype Bavaria, which is further subdivided into four geographical clusters. The entire N protein, harbouring an amino-terminal hexahistidine tag, of the Bavarian strain was produced in yeast Saccharomyces cerevisiae and showed a slightly different reactivity with N-specific monoclonal antibodies, compared to the yeast-expressed N protein of the PUUV strain Vranica/Hallnas. Endpoint titration of human sera from different parts of Germany and from Finland revealed only very slight differences in the diagnostic value of the different recombinant proteins. Based on the novel N antigen indirect and monoclonal antibody capture IgG-ELISAs were established. By using serum panels from Germany and Finland their validation demonstrated a high sensitivity and specificity. In summary, our investigations demonstrated the Bavarian PUUV strain to be genetically divergent from other PUUV strains and the potential of its N protein for diagnostic applications.

Tick-Borne Encephalitis: From Microfocus to Human Disease

Abstract: Ticks transmit a number of pathogens to humans and animals. Among them, the most important arboviral human disease in Central Europe and Northern Asia is tick-borne encephalitis (TBE). The Western subtype of TBE virus (TBEV) in Central Europe is mainly transmitted by the tick Ixodes ricinus. The incidence and the numbers of human cases are thought to be correlated to tick activity. Two different, but closely located TBEV endemic foci in South Eastern Germany were studied. The results of our longitudinal studies in both foci showed that the areas, where positive ticks could be repeatedly detected, were relatively small in comparison to earlier descriptions. The data of two endemic foci of TBEV imply that the natural circulation of TBEV between ticks and rodents or other small mammals occurs in rather small areas, named microfoci. From these microfoci, TBEV-bearing ticks are dispersed eventually, probably by larger forest animals with a greater radius of activity than rodents. Human infection occurs if humans enter the microfocus area or if infected ticks are dispersed and occasionally come into contact with humans, for example in gardens near forests or on forest ways within the area of activity of the larger forest animals, named macrofocus or endemic area. Further studies are needed to show whether this concept of TBEV microfocus and TBEV macrofocus will also apply to other endemic areas such as for example in Southwestern Germany.

MLVA and SNP analysis identified a unique genetic cluster in Bulgarian Bacillus anthracis strains.

Abstract: A collection of 40 Bacillus anthracis strains mostly isolated from soil in Bulgaria between 1960 and 1980 were investigated. All strains were proven to be B. anthracis by culture and amplification of a B. anthracis-specific chromosomal marker. PCR demonstrated that in nine strains both virulence plasmids (pX01+/pX02+) and in four strains only one plasmid (pX02+) were present, whereas the majority of strains (n = 27) lacked both plasmids (pX01-/pX02-). Multi-locus-variable number of tandem repeat-analysis (MLVA) using 15 markers differentiated three genotypes. Comparison with typing data of more than 1,000 different B. anthracis strains revealed that Bulgarian genotypes affiliated with the A1.a cluster and form their own unique cluster different from clusters containing strains isolated in geographical proximity, e.g., Turkey, Georgia, Hungary, Albania or Italy. In addition, a new allele of one marker (vrrC2) was identified. Canonical single nucleotide polymorphisms analysis allocated 31 Bulgarian strains into the A.Br.008/009 and nine strains into the A.Br.WNA group, which is the first description of B. anthracis strains of the A.Br.WNA group on the Eurasian continent.

A new permanent cell line derived from the bank vole (Myodes glareolus) as cell culture model for zoonotic viruses

Abstract: Background Approximately 60% of emerging viruses are of zoonotic origin, with three-fourths derived from wild animals. Many of these zoonotic diseases are transmitted by rodents with important information about their reservoir dynamics and pathogenesis missing. One main reason for the gap in our knowledge is the lack of adequate cell culture systems as models for the investigation of rodent-borne (robo) viruses in vitro. Therefore we established and characterized a new cell line, BVK168, using the kidney of a bank vole, Myodes glareolus, the most abundant member of the Arvicolinae trapped in Germany.