Species richness and abundance of low-trunk herb epiphytes in relation to host tree size and bark type, Eastern Amazonia

A composição e estrutura da comunidade epifítica herbácea de fuste baixo, assim como sua distribuição vertical, foram estudadas. O DAP de hospedeiros arbóreos e o tipo de casca influenciam a riqueza e abundância dessas espécies em um trecho de floresta de terra firme na Amazônia Oriental (1º57’36"S 51º36’55"W). Foram identificadas, no total, 37 espécies herbáceas epifíticas, sendo 60% delas Araceae. A riqueza de espécies e a abundância de herbáceas epifíticas mostraram tendência de correlação positiva com o tamanho de hospedeiros arbóreos e nenhuma relação com o tipo de casca. Correlação positiva baixa pode ser um subproduto da predominância de árvores de menor diâmetro na amostragem em vez de refletir relação neutra. A ausência de relações com o tipo de casca deve ser parcialmente explicada pelo grande número de hemiepífitas secundárias, generalistas, e também refletir a ausência de substratos adequados em árvores de menor diâmetro.

Community structure and dynamics of Monogenea and Trematoda in three North American cyprinid species in the Salt Valley Watershed, Nebraska.

An investigation was made of the communities of gill monogene genus Dactylogyrus (Platyhelminthes, Monogenea) and the populations of blackspot parasite (Platyhelminthes, Trematoda) of Pimephales promelas, Notropis stramineus, and Semotilus atromaculatus in 3 distinct sites along the 3 converging tributaries in southeastern Nebraska from 2004 to 2006. This work constitutes the first multi-site, multi-year study of a complex community of Dactylogyrus spp. and their reproductive activities on native North American cyprinid species. The biological hypothesis that closely related species with direct lifecycles respond differently to shared environmental conditions was tested. It was revealed that in this system that, Cyprinid species do not share Dactylogyrus species, host size and sex are not predictive of infection, and Dactylogyrus community structure is stable, despite variation in seasonal occurrence and populations among sites. The biological hypothesis that closely related species have innate differences in reproductive activities that provide structure to their populations and influence their roles in the parasite community was tested. It was revealed that in this system, host size, sex, and collection site are not predictive of reproductive activities, that egg production is not always continuous and varies in duration among congeners, and that recruitment of larval Dactylogyrus is not continuous across parasites’ reproductive periods. Hatch timing and host availability, not reproductive timing, are the critical factors determining population dynamics of the gill monogenes in time and space. Lastly, the biological hypothesis that innate blackspot biology is responsible for parasite host-specificity, host recruitment strategies and parasite population structure was tested. Field collections revealed that for blackspot, host size, sex, and collection month and year are not predictive of infection, that parasite cysts survive winter, and that host movement is restricted among the 3 collection sites. Finally, experimental infections of hosts with cercaria isolated from 1st intermediate snail hosts reveal that cercarial biology, not environmental circumstances, are responsible for differences in infection among hosts.

Echinococcus granulosus Antigen B Structure: Subunit Composition and Oligomeric States

Background: Antigen B (AgB) is the major protein secreted by the Echinococcus granulosus metacestode and is involved in key host-parasite interactions during infection. The full comprehension of AgB functions depends on the elucidation of several structural aspects that remain unknown, such as its subunit composition and oligomeric states. Methodology/Principal Findings: The subunit composition of E. granulosus AgB oligomers from individual bovine and human cysts was assessed by mass spectrometry associated with electrophoretic analysis. AgB8/1, AgB8/2, AgB8/3 and AgB8/4 subunits were identified in all samples analyzed, and an AgB8/2 variant (AgB8/2v8) was found in one bovine sample. The exponentially modified protein abundance index (emPAI) was used to estimate the relative abundance of the AgB subunits, revealing that AgB8/1 subunit was relatively overrepresented in all samples. The abundance of AgB8/3 subunit varied between bovine and human cysts. The oligomeric states formed by E. granulosus AgB and recombinant subunits available, rAgB8/1, rAgB8/2 and rAgB8/3, were characterized by native PAGE, light scattering and microscopy. Recombinant subunits showed markedly distinct oligomerization behaviors, forming oligomers with a maximum size relation of rAgB8/3 >rAgB8/2>rAgB8/1. Moreover, the oligomeric states formed by rAgB8/3 subunit were more similar to those observed for AgB purified from hydatid fluid. Pressure-induced dissociation experiments demonstrated that the molecular assemblies formed by the more aggregative subunits, rAgB8/2 and rAgB8/3, also display higher structural stability. Conclusions/Significance: For the first time, AgB subunit composition was analyzed in samples from single hydatid cysts, revealing qualitative and quantitative differences between samples. We showed that AgB oligomers are formed by different subunits, which have distinct abundances and oligomerization properties. Overall, our findings have significantly contributed to increase the current knowledge on AgB expression and structure, highlighting issues that may help to understand the parasite adaptive response during chronic infection.

Mistletoes Play Different Roles in a Modular Host-Parasite Network

Antagonistic interactions between host plants and mistletoes often form complex networks of interacting species. Adequate characterization of network organization requires a combination of qualitative and quantitative data. Therefore, we assessed the distribution of interactions between mistletoes and hosts in the Brazilian Pantanal and characterized the network structure in relation to nestedness and modularity. Interactions were highly asymmetric, with mistletoes presenting low host specificity (i.e., weak dependence) and with hosts being highly susceptible to mistletoe-specific infections. We found a non-nested and modular pattern of interactions, wherein each mistletoe species interacted with a particular set of host species. Psittacanthus spp. infected more species and individuals and also caused a high number of infections per individual, whereas the other mistletoes showed a more specialized pattern of infection. For this reason, Psittacanthus spp. were regarded as module hubs while the other mistletoe species showed a peripheral role. We hypothesize that this pattern is primarily the result of different seed dispersal systems. Although all mistletoe species in our study are bird dispersed, the frugivorous assemblage of Psittacanthus spp. is composed of a larger suite of birds, whereas Phoradendron are mainly dispersed by Euphonia species. The larger assemblage of bird species dispersing Psittacanthus seeds may also increase the number of hosts colonized and, consequently, its dominance in the study area. Nevertheless, other restrictions on the interactions among species, such as the differential capacity of mistletoe infections, defense strategies of hosts and habitat types, can also generate or enhance the observed pattern.

Host-guest interactions between xanthones and water: the role of O-H center dot center dot center dot O, C-H center dot center dot center dot O, and pi center dot center dot center dot pi contacts in the channel- and cage-type frameworks

In this article were studied two xanthone derivatives known as 1,5-dihydroxy-8-methoxyxanthone (I) and 1,3,7-trihydroxy-8-methoxyxanthone (II), which show one water molecule into their crystal structures. In xanthone I, there are water wires contributing to build up channel-like cavities along the c axis, whereas in xanthone II the water is surrounded by three xanthone molecules forming a cage-type structure. The geometries of I and II were optimized using the density functional theory method with B3LYP functional, and the results were compared with crystal structure. Both theoretical and experimental investigations reveal a concordance between structural parameters, with the xanthone core presenting an almost flat conformation and substituents adopting the more stable orientations. In the two compounds, the hydroxyl group linked at position 1 is involved in a resonance-assisted hydrogen bond with the carbonyl group. Besides, the supramolecular arrangement of the host/guest systems are stabilized mainly by classical intermolecular hydrogen bonds (O-H center dot center dot center dot O) involving xanthone-to-water and xanthone-to-xanthone. In addition, C-H center dot center dot center dot O weak hydrogen bonds, as well as pi-pi interactions play an important role to stabilize the crystal self-assembly of xanthones I and II. The results reported here underline the role of inclusion of water molecules and their different arrangement into the crystal structure of two xanthone host/guest systems.

CLEANING ASSOCIATIONS BETWEEN BIRDS AND HERBIVOROUS MAMMALS IN BRAZIL: STRUCTURE AND COMPLEXITY

Birds that remove ectoparasites and other food material from their hosts are iconic illustrations of mutualistic-commensalistic cleaning associations. To assess the complex pattern of food resource use embedded in cleaning interactions of an assemblage of birds and their herbivorous mammal hosts in open habitats in Brazil, we used a network approach that characterized their patterns of association. Cleaning interactions showed a distinctly nested pattern, related to the number of interactions of cleaners and hosts and to the range of food types that each host species provided. Hosts that provided a wide range of food types (flies, ticks, tissue and blood, and organic debris) were attended by more species of cleaners and formed the core of the web. On the other hand, core cleaner species did not exploit the full range of available food resources, but used a variety of host species to exploit these resources instead. The structure that we found indicates that cleaners rely on cleaning interactions to obtain food types that would not be available otherwise (e.g., blood-engorged ticks or horseflies, wounded tissue). Additionally, a nested organization for the cleaner bird mammalian herbivore association means that both generalist and selective species take part in the interactions and that partners of selective species form an ordered subset of the partners of generalist species. The availability of predictable protein-rich food sources for birds provided by cleaning interactions may lead to an evolutionary pathway favoring their increased use by birds that forage opportunistically. Received 30 June 2011, accepted 10 November 2011.

New insights regarding HCV-NS5A structure/function and indication of genotypic differences

Abstract Background HCV is prevalent throughout the world. It is a major cause of chronic liver disease. There is no effective vaccine and the most common therapy, based on Peginterferon, has a success rate of ~50%. The mechanisms underlying viral resistance have not been elucidated but it has been suggested that both host and virus contribute to therapy outcome. Non-structural 5A (NS5A) protein, a critical virus component, is involved in cellular and viral processes. Methods The present study analyzed structural and functional features of 345 sequences of HCV-NS5A genotypes 1 or 3, using in silico tools. Results There was residue type composition and secondary structure differences between the genotypes. In addition, second structural variance were statistical different for each response group in genotype 3. A motif search indicated conserved glycosylation, phosphorylation and myristoylation sites that could be important in structural stabilization and function. Furthermore, a highly conserved integrin ligation site was identified, and could be linked to nuclear forms of NS5A. ProtFun indicated NS5A to have diverse enzymatic and nonenzymatic activities, participating in a great range of cell functions, with statistical difference between genotypes. Conclusion This study presents new insights into the HCV-NS5A. It is the first study that using bioinformatics tools, suggests differences between genotypes and response to therapy that can be related to NS5A protein features. Therefore, it emphasizes the importance of using bioinformatics tools in viral studies. Data acquired herein will aid in clarifying the structure/function of this protein and in the development of antiviral agents.

Computational methods for the analysis of protein structure and function

The vast majority of known proteins have not yet been experimentally characterized and little is known about their function. The design and implementation of computational tools can provide insight into the function of proteins based on their sequence, their structure, their evolutionary history and their association with other proteins. Knowledge of the three-dimensional (3D) structure of a protein can lead to a deep understanding of its mode of action and interaction, but currently the structures of <1% of sequences have been experimentally solved. For this reason, it became urgent to develop new methods that are able to computationally extract relevant information from protein sequence and structure. The starting point of my work has been the study of the properties of contacts between protein residues, since they constrain protein folding and characterize different protein structures. Prediction of residue contacts in proteins is an interesting problem whose solution may be useful in protein folding recognition and de novo design. The prediction of these contacts requires the study of the protein inter-residue distances related to the specific type of amino acid pair that are encoded in the so-called contact map. An interesting new way of analyzing those structures came out when network studies were introduced, with pivotal papers demonstrating that protein contact networks also exhibit small-world behavior. In order to highlight constraints for the prediction of protein contact maps and for applications in the field of protein structure prediction and/or reconstruction from experimentally determined contact maps, I studied to which extent the characteristic path length and clustering coefficient of the protein contacts network are values that reveal characteristic features of protein contact maps. Provided that residue contacts are known for a protein sequence, the major features of its 3D structure could be deduced by combining this knowledge with correctly predicted motifs of secondary structure. In the second part of my work I focused on a particular protein structural motif, the coiled-coil, known to mediate a variety of fundamental biological interactions. Coiled-coils are found in a variety of structural forms and in a wide range of proteins including, for example, small units such as leucine zippers that drive the dimerization of many transcription factors or more complex structures such as the family of viral proteins responsible for virus-host membrane fusion. The coiled-coil structural motif is estimated to account for 5-10% of the protein sequences in the various genomes. Given their biological importance, in my work I introduced a Hidden Markov Model (HMM) that exploits the evolutionary information derived from multiple sequence alignments, to predict coiled-coil regions and to discriminate coiled-coil sequences. The results indicate that the new HMM outperforms all the existing programs and can be adopted for the coiled-coil prediction and for large-scale genome annotation. Genome annotation is a key issue in modern computational biology, being the starting point towards the understanding of the complex processes involved in biological networks. The rapid growth in the number of protein sequences and structures available poses new fundamental problems that still deserve an interpretation. Nevertheless, these data are at the basis of the design of new strategies for tackling problems such as the prediction of protein structure and function. Experimental determination of the functions of all these proteins would be a hugely time-consuming and costly task and, in most instances, has not been carried out. As an example, currently, approximately only 20% of annotated proteins in the Homo sapiens genome have been experimentally characterized. A commonly adopted procedure for annotating protein sequences relies on the "inheritance through homology" based on the notion that similar sequences share similar functions and structures. This procedure consists in the assignment of sequences to a specific group of functionally related sequences which had been grouped through clustering techniques. The clustering procedure is based on suitable similarity rules, since predicting protein structure and function from sequence largely depends on the value of sequence identity. However, additional levels of complexity are due to multi-domain proteins, to proteins that share common domains but that do not necessarily share the same function, to the finding that different combinations of shared domains can lead to different biological roles. In the last part of this study I developed and validate a system that contributes to sequence annotation by taking advantage of a validated transfer through inheritance procedure of the molecular functions and of the structural templates. After a cross-genome comparison with the BLAST program, clusters were built on the basis of two stringent constraints on sequence identity and coverage of the alignment. The adopted measure explicity answers to the problem of multi-domain proteins annotation and allows a fine grain division of the whole set of proteomes used, that ensures cluster homogeneity in terms of sequence length. A high level of coverage of structure templates on the length of protein sequences within clusters ensures that multi-domain proteins when present can be templates for sequences of similar length. This annotation procedure includes the possibility of reliably transferring statistically validated functions and structures to sequences considering information available in the present data bases of molecular functions and structures.

Transposable elements: structure and dynamic of the autonomous retrotransposon R2 in Arthropoda with non-canonical reproduction

Eukaryotic ribosomal DNA constitutes a multi gene family organized in a cluster called nucleolar organizer region (NOR); this region is composed usually by hundreds to thousands of tandemly repeated units. Ribosomal genes, being repeated sequences, evolve following the typical pattern of concerted evolution. The autonomous retroelement R2 inserts in the ribosomal gene 28S, leading to defective 28S rDNA genes. R2 element, being a retrotransposon, performs its activity in the genome multiplying its copy number through a “copy and paste” mechanism called target primed reverse transcription. It consists in the retrotranscription of the element’s mRNA into DNA, then the DNA is integrated in the target site. Since the retrotranscription can be interrupted, but the integration will be carried out anyway, truncated copies of the element will also be present in the genome. The study of these truncated variants is a tool to examine the activity of the element. R2 phylogeny appears, in general, not consistent with that of its hosts, except some cases (e.g. Drosophila spp. and Reticulitermes spp.); moreover R2 is absent in some species (Fugu rubripes, human, mouse, etc.), while other species have more R2 lineages in their genome (the turtle Mauremys reevesii, the Japanese beetle Popilia japonica, etc). R2 elements here presented are isolated in 4 species of notostracan branchiopods and in two species of stick insects, whose reproductive strategies range from strict gonochorism to unisexuality. From sequencing data emerges that in Triops cancriformis (Spanish gonochoric population), in Lepidurus arcticus (two putatively unisexual populations from Iceland) and in Bacillus rossius (gonochoric population from Capalbio) the R2 elements are complete and encode functional proteins, reflecting the general features of this family of transposable elements. On the other hand, R2 from Italian and Austrian populations of T. cancriformis (respectively unisexual and hermaphroditic), Lepidurus lubbocki (two elements within the same Italian population, gonochoric but with unfunctional males) and Bacillus grandii grandii (gonochoric population from Ponte Manghisi) have sequences that encode incomplete or non-functional proteins in which it is possible to recognize only part of the characteristic domains. In Lepidurus couesii (Italian gonochoric populations) different elements were found as in L. lubbocki, and the sequencing is still in progress. Two hypothesis are given to explain the inconsistency of R2/host phylogeny: vertical inheritance of the element followed by extinction/diversification or horizontal transmission. My data support previous study that state the vertical transmission as the most likely explanation; nevertheless horizontal transfer events can’t be excluded. I also studied the element’s activity in Spanish populations of T. cancriformis, in L. lubbocki, in L. arcticus and in gonochoric and parthenogenetic populations of B. rossius. In gonochoric populations of T. cancriformis and B. rossius I found that each individual has its own private set of truncated variants. The situation is the opposite for the remaining hermaphroditic/parthenogenetic species and populations, all individuals sharing – in the so far analyzed samples - the majority of variants. This situation is very interesting, because it isn’t concordant with the Muller’s ratchet theory that hypothesizes the parthenogenetic populations being either devoided of transposable elements or TEs overloaded. My data suggest a possible epigenetic mechanism that can block the retrotransposon activity, and in this way deleterious mutations don’t accumulate.

Echinococcus multilocularis phosphoglucose isomerase (EmPGI): a glycolytic enzyme involved in metacestode growth and parasite-host cell interactions

In Echinococcus multilocularis metacestodes, the surface-associated and highly glycosylated laminated layer, and molecules associated with this structure, is believed to be involved in modulating the host-parasite interface. We report on the molecular and functional characterisation of E. multilocularis phosphoglucose isomerase (EmPGI), which is a component of this laminated layer. The EmPGI amino acid sequence is virtually identical to that of its homologue in Echinococcus granulosus, and shares 64% identity and 86% similarity with human PGI. Mammalian PGI is a multi-functional protein which, besides its glycolytic function, can also act as a cytokine, growth factor and inducer of angiogenesis, and plays a role in tumour growth, development and metastasis formation. Recombinant EmPGI (recEmPGI) is also functionally active as a glycolytic enzyme and was found to be present, besides the laminated layer, in vesicle fluid and in germinal layer cell extracts. EmPGI is released from metacestodes and induces a humoral immune response in experimentally infected mice, and vaccination of mice with recEmPGI renders these mice more resistant towards secondary challenge infection, indicating that EmPGI plays an important role in parasite development and/or in modulating the host-parasite relationship. We show that recEmPGI stimulates the growth of isolated E. multilocularis germinal layer cells in vitro and selectively stimulates the proliferation of bovine adrenal cortex endothelial cells but not of human fibroblasts and rat hepatocytes. Thus, besides its role in glycolysis, EmPGI could also act as a factor that stimulates parasite growth and potentially induces the formation of novel blood vessels around the developing metacestode in vivo.

Hydrodynamic Characterization of Bile Salt Host-Guest Complexes by Pulsed Field Gradient NMR Spectroscopy

The work described herein is aimed at understanding primary and secondary aggregation of bile salt micelles and how micelles can perform chiral recognition of binapthyl analytes. Previous work with cholate and deoxycholate using micellar electrokinetic chromatography (MEKC) and nuclear magnetic resonance (NMR) has provided insightinto cholate and deoxycholate micelle formation, especially with respect to the critical micelle concentration (CMC). Chiral separations of the model analyte, 1,1â??-binaphthyl-2,2â??-diyl hydrogen phosphate (BNDHP), via cholate (C) and deoxycholate (DC) mediated MEKC separataions previously have shown the DC CMC to be 7-10 mM andthe cholate CMC at 14 mM at ph 12. A second model analyte,1,1â??-binaphthol (BN), was also previously investigated to probe micellar structure, but the MEKC data for this analyte implied a higher CMC, which may be interpreted as secondary aggregation. Thiswork extends the investigation of bile salts to include pulsed field gradient spin echo (PFGSE) NMR experiments being used to gain information about the size and degree of polydispersity of cholate and deoxycholate micelles. Concentrations of cholate below 10mM show a large variation in effective radius likely due to the existence of transient preliminary aggregates. The onset of the primary micelle shows a dramatic increase in effective radius of the micelle in cholate and deoxycholate. In the region of expectedsecondary aggregation a gradual increase of effective radius was observed with cholate; deoxycholate showed a persistent aggregate size in the secondary micelle region that is modulated by the presence of an analyte molecule. Effective radii of cholate anddeoxycholate (individually) were compared with and without R- and S-BNDHP in order to observe the effective radius difference of micelles with and without analyte present. The presence of S-BNDHP consistently resulted in a larger effective aggregate radius incholate and deoxycholate, confirming previous data of the S-BNDHP interacting more with the micelle than R-BNDHP. In total, various NMR techniques, like diffusion NMR can be used to gain a greater understanding of the bile salt micellization process and chiral resolution.

Host responses to intestinal microbial antigens in gluten-sensitive mice

BACKGROUND AND AIMS: Excessive uptake of commensal bacterial antigens through a permeable intestinal barrier may influence host responses to specific antigen in a genetically predisposed host. The aim of this study was to investigate whether intestinal barrier dysfunction induced by indomethacin treatment affects the host response to intestinal microbiota in gluten-sensitized HLA-DQ8/HCD4 mice. METHODOLOGY/PRINCIPAL FINDINGS: HLA-DQ8/HCD4 mice were sensitized with gluten, and gavaged with indomethacin plus gluten. Intestinal permeability was assessed by Ussing chamber; epithelial cell (EC) ultra-structure by electron microscopy; RNA expression of genes coding for junctional proteins by Q-real-time PCR; immune response by in-vitro antigen-specific T-cell proliferation and cytokine analysis by cytometric bead array; intestinal microbiota by fluorescence in situ hybridization and analysis of systemic antibodies against intestinal microbiota by surface staining of live bacteria with serum followed by FACS analysis. Indomethacin led to a more pronounced increase in intestinal permeability in gluten-sensitized mice. These changes were accompanied by severe EC damage, decreased E-cadherin RNA level, elevated IFN-gamma in splenocyte culture supernatant, and production of significant IgM antibody against intestinal microbiota. CONCLUSION: Indomethacin potentiates barrier dysfunction and EC injury induced by gluten, affects systemic IFN-gamma production and the host response to intestinal microbiota antigens in HLA-DQ8/HCD4 mice. The results suggest that environmental factors that alter the intestinal barrier may predispose individuals to an increased susceptibility to gluten through a bystander immune activation to intestinal microbiota.

HIV infection disrupts the sympatric host-pathogen relationship in human tuberculosis

The phylogeographic population structure of Mycobacterium tuberculosis suggests local adaptation to sympatric human populations. We hypothesized that HIV infection, which induces immunodeficiency, will alter the sympatric relationship between M. tuberculosis and its human host. To test this hypothesis, we performed a nine-year nation-wide molecular-epidemiological study of HIV-infected and HIV-negative patients with tuberculosis (TB) between 2000 and 2008 in Switzerland. We analyzed 518 TB patients of whom 112 (21.6%) were HIV-infected and 233 (45.0%) were born in Europe. We found that among European-born TB patients, recent transmission was more likely to occur in sympatric compared to allopatric host-pathogen combinations (adjusted odds ratio [OR] 7.5, 95% confidence interval [95% CI] 1.21-infinity, p = 0.03). HIV infection was significantly associated with TB caused by an allopatric (as opposed to sympatric) M. tuberculosis lineage (OR 7.0, 95% CI 2.5-19.1, p<0.0001). This association remained when adjusting for frequent travelling, contact with foreigners, age, sex, and country of birth (adjusted OR 5.6, 95% CI 1.5-20.8, p = 0.01). Moreover, it became stronger with greater immunosuppression as defined by CD4 T-cell depletion and was not the result of increased social mixing in HIV-infected patients. Our observation was replicated in a second independent panel of 440 M. tuberculosis strains collected during a population-based study in the Canton of Bern between 1991 and 2011. In summary, these findings support a model for TB in which the stable relationship between the human host and its locally adapted M. tuberculosis is disrupted by HIV infection.

KLIKK proteases of Tannerella forsythia: putative virulence factors with a unique domain structure.

Comparative genomics of virulent Tannerella forsythia ATCC 43037 and a close health-associated relative, Tannerella BU063, revealed, in the latter, the absence of an entire array of genes encoding putative secretory proteases that possess a nearly identical C-terminal domain (CTD) that ends with a -Lys-Leu-Ile-Lys-Lys motif. This observation suggests that these proteins, referred to as KLIKK proteases, may function as virulence factors. Re-sequencing of the loci of the KLIKK proteases found only six genes grouped in two clusters. All six genes were expressed by T. forsythia in routine culture conditions, although at different levels. More importantly, a transcript of each gene was detected in gingival crevicular fluid (GCF) from periodontitis sites infected with T. forsythia indicating that the proteases are expressed in vivo. In each protein, a protease domain was flanked by a unique N-terminal profragment and a C-terminal extension ending with the CTD. Partially purified recombinant proteases showed variable levels of proteolytic activity in zymography gels and toward protein substrates, including collagen, gelatin, elastin, and casein. Taken together, these results indicate that the pathogenic strain of T. forsythia secretes active proteases capable of degrading an array of host proteins, which likely represents an important pathogenic feature of this bacterium.

Spatiotemporal dynamics of Puumala hantavirus associated with its rodent host, Myodes glareolus

Many viruses significantly impact human and animal health. Understanding the population dynamics of these viruses and their hosts can provide important insights for epidemiology and virus evolution. Puumala virus (PUUV) is a European hantavirus that may cause regional outbreaks of hemorrhagic fever with renal syndrome in humans. Here, we analyzed the spatiotemporal dynamics of PUUV circulating in local populations of its rodent reservoir host, the bank vole (Myodes glareolus) during eight years. Phylogenetic and population genetic analyses of all three genome segments of PUUV showed strong geographical structuring at a very local scale. There was a high temporal turnover of virus strains in the local bank vole populations, but several virus strains persisted through multiple years. Phylodynamic analyses showed no significant changes in the local effective population sizes of PUUV, although vole numbers and virus prevalence fluctuated widely. Microsatellite data demonstrated also a temporally persisting subdivision between local vole populations, but these groups did not correspond to the subdivision in the virus strains. We conclude that restricted transmission between vole populations and genetic drift play important roles in shaping the genetic structure and temporal dynamics of PUUV in its natural host which has several implications for zoonotic risks of the human population.