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The baculovirus-insect cell expression system is readily utilized to produce viral glycoproteins for research as well as for subunit vaccines and vaccine candidates, for instance against SARS-CoV-2 infections. However, the glycoforms of recombinant proteins derived from this expression system are inherently different from mammalian cell-derived glycoforms with mainly complex-type N-glycans attached, and the impact of these differences in protein glycosylation on the immunogenicity is severely under investigated. This applies also to the SARS-CoV-2 spike glycoprotein, which is the antigen target of all licensed vaccines and vaccine candidates including virus like particles and subunit vaccines that are variants of the spike protein. Here, we expressed the transmembrane-deleted human β-1,2 N-acetlyglucosamintransferases I and II (MGAT1ΔTM and MGAT2ΔTM) and the β-1,4-galactosyltransferase (GalTΔTM) in E. coli to in-vitro remodel the N-glycans of a recombinant SARS-CoV-2 spike glycoprotein derived from insect cells. In a cell-free sequential one-pot reaction, fucosylated and afucosylated paucimannose-type N-glycans were converted to complex-type galactosylated N-glycans. In the future, this in-vitro glycoengineering approach can be used to efficiently generate a wide range of N-glycans on antigens considered as vaccine candidates for animal trials and preclinical testing to better characterize the impact of N-glycosylation on immunity and to improve the efficacy of protein subunit vaccines.

Background Migratory birds can cross geographical and environmental barriers and are thereby able to facilitate transmission of tick-borne pathogens both as carriers of infected ticks and as reservoirs of pathogenic microorganisms. Ixodes ricinus is one of the most abundant tick species in the Northern Hemisphere and a main vector of several Babesia species, some which pose a potential threat to human and animal health. At present only two cases of overt babesiosis in humans have so far been reported in Sweden. To better understand the potential role of birds as disseminators of zoonotic Babesia protozoan parasites, we investigated the presence of Babesia species in ticks removed from migratory birds. Methods Ticks were collected from birds captured at Ottenby Bird Observatory, south-eastern Sweden, from March to November 2009. Ticks were molecularly identified to species, and morphologically to developmental stage, and the presence of Babesia protozoan parasites was determined by real-time PCR. Results In total, 4601 migratory birds of 65 species were examined for tick infestation. Ticks removed from these birds have previously been investigated for the presence of Borrelia bacteria and the tick-borne encephalitis virus. In the present study, a total of 1102 ticks were available for molecular analysis of Babesia protozoan parasites. We found that 2.4% of the ticks examined, all I. ricinus, were positive for mammal-associated Babesia species. Out of all Babesia-positive samples, Babesia venatorum was the most prevalent (58%) species, followed by Babesia microti (38%) and Babesia capreoli (4.0%). B. venatorum and B. capreoli were detected in I. ricinus larvae, whereas B. microti was only present in I. ricinus nymphs. This supports the view that the two first-mentioned species are vertically (transovarially) transmitted in the tick population, in contrast to B. microti. The largest number of Babesia-infected ticks was removed from the common redstart (Phoenicurus phoenicurus) and European robin (Erithacus rubecula). Conclusions This study reveals that Babesia protozoan parasites are present in ticks infesting migratory birds in south-eastern Sweden, which could potentially lead to the dissemination of these tick-borne microorganisms into new areas, thus posing a threat to humans and other mammals. Graphical Abstract

Significance Diseases associated with amyloid formation affect millions of people worldwide. Great progress has been made to understand the process of amyloid formation in test tube reactions, but it has so far remained unclear if the same biophysical principles also dominate in living cells and organisms. Here, we use the nematode C. elegans to demonstrate that we can apply kinetic modeling approaches to quantitatively analyze the process of protein aggregation in a living animal. The mathematical models that we develop are not restricted to this system and are applicable to other disease-associated proteins and animal models. The ability to quantitatively understand aggregation mechanisms in living organisms will be critical to advance our understanding of human disease and to design therapeutic strategies., Protein aggregation is associated with a wide range of degenerative human diseases with devastating consequences, as exemplified by Alzheimer’s, Parkinson’s, and Huntington’s diseases. In vitro kinetic studies have provided a mechanistic understanding of the aggregation process at the molecular level. However, it has so far remained largely unclear to what extent the biophysical principles of amyloid formation learned in vitro translate to the complex environment of living organisms. Here, we take advantage of the unique properties of a Caenorhabditis elegans model expressing a fluorescently tagged polyglutamine (polyQ) protein, which aggregates into discrete micrometer-sized inclusions that can be directly visualized in real time. We provide a quantitative analysis of protein aggregation in this system and show that the data are described by a molecular model where stochastic nucleation occurs independently in each cell, followed by rapid aggregate growth. Global fitting of the image-based aggregation kinetics reveals a nucleation rate corresponding to 0.01 h−1 per cell at 1 mM intracellular protein concentration, and shows that the intrinsic molecular stochasticity of nucleation accounts for a significant fraction of the observed animal-to-animal variation. Our results highlight how independent, stochastic nucleation events in individual cells control the overall progression of polyQ aggregation in a living animal. The key finding that the biophysical principles associated with protein aggregation in small volumes remain the governing factors, even in the complex environment of a living organism, will be critical for the interpretation of in vivo data from a wide range of protein aggregation diseases.

The bat tick Cariosvespertilionis has been reported from Sweden to occasionally feed on humans resulting in disease symptoms. The aim of this study was to investigate C. vespertilionis as a potential vector and reservoir of Borrelia species. In 2015 and 2018 in south-central Sweden, C. vespertilionis ticks were collected from a wooden bat box harboring Soprano pipistrelle bats, Pipistrellus pygmaeus. In addition, one C. vespertilionis tick found inside a house in southern Sweden in 2019 was collected. Ticks were screened for Borrelia spp. using a genus-specific quantitative PCR assay. The Borrelia species of the positive specimens were determined by conventional PCR followed by DNA sequencing and phylogenetic analyses. A total of 24% (22 of 92) of the analyzed C. vespertilionis ticks were Borrelia-positive. Phylogenetic analyses indicate that the bacteria belong to the relapsing fever group of borreliae, some of them appear to be identical with Borrelia sp. CPB1, a spirochete only found twice before—in the United Kingdom and in France. Our results also indicate a temporal and spatial distribution of this Borrelia species. Since C. vespertilionis occasionally bites humans, and since it exhibits a high prevalence of Borrelia bacteria, it is possible that it presents a risk of human disease. Further studies are needed to characterize Borrelia sp. CPB1 to determine if it is human-pathogenic and to determine if C. vespertilionis is a vector and/or reservoir of this agent.

Background Birds can act as reservoirs of tick-borne pathogens and can also disperse pathogen-containing ticks to both nearby and remote localities. The aims of this study were to estimate tick infestation patterns on migratory birds and the prevalence of different Borrelia species and tick-borne encephalitis virus (TBEV) in ticks removed from birds in south-eastern Sweden. Methods Ticks were collected from resident and migratory birds captured at the Ottenby Bird Observatory, Öland, Sweden, from March to November 2009. Ticks were molecularly identified to species, and morphologically to developmental stage, and the presence of Borrelia bacteria and TBEV was determined by quantitative real-time PCR. Results A total of 1339 ticks in the genera Haemaphysalis, Hyalomma, and Ixodes was recorded of which I. ricinus was the most abundant species. Important tick hosts were the European robin (Erithacus rubecula), Blackbird (Turdus merula), Tree pipit (Anthus trivialis), Eurasian wren (Troglodytes troglodytes), Common redstart (Phoenicurus phoenicurus), Willow warbler (Phylloscopus trochilus), and Common whitethroat (Sylvia communis). Borrelia bacteria were detected in 25% (285/1,124) of the detached ticks available for analysis. Seven Borrelia species (B. afzelii, B. burgdorferi (s.s.), B. garinii, B. lusitaniae, B. turdi, B. valaisiana, and B. miyamotoi) were identified. B. turdi was recorded for the first time in ticks in Sweden. The number of Borrelia cells per tick ranged from 2.0 × 100 to 7.0 × 105. B. miyamotoi-containing ticks contained a significantly higher median number of Borrelia cells than B. burgdorferi (s.l.)-containing ticks. B. garinii and B. miyamotoi were the most prevalent Borrelia species in tick larvae. Larvae of I. ricinus with B. garinii were removed from seven bird species, particularly S. communis and A. trivialis, which may suggest that the larvae had contracted the Borrelia bacteria from or via these birds. Also, a high percentage of tick larvae containing B. miyamotoi was removed from E. rubecula. All ticks were negative for TBEV. Conclusions The results corroborate the view that the contributions of birds to human disease are substantial, particularly as blood hosts for ticks and for their short-, medium-, and long-distance dispersal. Moreover, several ground-foraging bird species appear to be important for the maintenance and dispersal of Borrelia species. The absence of TBEV in the ticks conforms to other similar studies. Graphical Abstract

Significance Protein oligomers are increasingly recognized as the most cytotoxic forms of protein aggregates. It has been very challenging, however, to target these oligomers with therapeutic compounds, because of their dynamic and transient nature. To overcome this problem, we present here a “structure–kinetic-activity relationship” (SKAR) approach, which enables the discovery and systematic optimization of compounds that reduce the number of oligomers produced during an aggregation reaction. We illustrate this strategy for the amyloid beta peptide (Aβ), which is closely associated with Alzheimer’s disease, by developing a rhodanine compound capable of dramatically reducing the production of Aβ oligomers. As this strategy is general, it can be applied to oligomers of any protein., To develop effective therapeutic strategies for protein misfolding diseases, a promising route is to identify compounds that inhibit the formation of protein oligomers. To achieve this goal, we report a structure−activity relationship (SAR) approach based on chemical kinetics to estimate quantitatively how small molecules modify the reactive flux toward oligomers. We use this estimate to derive chemical rules in the case of the amyloid beta peptide (Aβ), which we then exploit to optimize starting compounds to curtail Aβ oligomer formation. We demonstrate this approach by converting an inactive rhodanine compound into an effective inhibitor of Aβ oligomer formation by generating chemical derivatives in a systematic manner. These results provide an initial demonstration of the potential of drug discovery strategies based on targeting directly the production of protein oligomers.

The intracellular adaptor protein Mint2 binds amyloid precursor protein (APP) and presenilin-1, which are both central constituents of the amyloidogenic pathway associated with Alzheimer's disease (AD). Additional interaction partners have also been suggested for Mint2; several of them are also pertinent to AD pathogenesis. However, no comparative mapping of the Mint2 protein-protein interaction network is available. Here we provide a systematic characterization of seven interaction partners and address their specificities towards the different binding domains of Mint2, which reveal domain-specific and -nonspecific interaction partners. Moreover, we show that the last two C-terminal amino acids of Mint2 are both important for the intramolecular interaction with the PDZ1 domain and for the stability of Mint2.

The ecology of the vertebrate host contributes to the geographical range expansion of ticks. In this study, we investigated which tick taxa that infest and are dispersed by birds along African-Western Palaearctic flyways during northward migration, and whether bird ecology was associated with tick taxa. Materials and methods: Ticks were collected from birds trapped at bird observatories in Spain, Italy, Greece, and Israel during the spring migration of 2014 and 2015, using mist nets. The tick-infested bird species were classified into guilds, using different combinations of the variables: migration distance, wintering region, foraging behaviour, and winter habitat. Ticks were molecularly determined to genus and species level by sequencing fragments of the 12S ribosomal DNA (rDNA) gene and by phylogenetic inference, using the Maximum Likelihood algorithm. Data were analysed using descriptive measures, graphs, Chi2 tests, the Tukey-Kramer test, and a parametric linear model (generalized linear model) in order to analyse and adjust for characteristics in the bird guilds and their relationship to collected tick taxa. Results: Most (84.2%) of the 10,209 trapped birds were long-distance migrants, of which 2.4% were infested by ticks. The most common tick species was Hyalomma rufipes (77.7%; 447/575), a known vector and reservoir of Crimean- Congo hemorrhagic fever virus. Bird guilds containing only long-distance migrants with wintering areas in Africa were associated with the tick species H. rufipes (p < 0.0001). Furthermore, bird winter habitat was associated with H. rufipes (p = 0.003); with bird species overwintering in open habitat (p = 0.014) and wetlands (p = 0.046) having significantly more H. rufipes as compared to birds with a winter habitat comprising forest and shrubs (p = 0.82). Conclusions: With climate change, the likelihood of establishment of permanent Hyalomma populations in central and northern Europe is increasing. Thus, surveillance programs for monitoring the risk of introduction and establishment of H. rufipes in the Western-Palaearctic should be established. Our study suggests that migratory bird species wintering in African open habitats and wetlands are good candidates for monitoring potential introduction.

Anaplasma phagocytophilum (AP) has vast geographical and host ranges and causes disease in humans and domesticated animals. We investigated the role of northward migratory birds in the dispersal of tick-borne AP in the African-Western Palearctic. Ticks were collected from northward migratory birds trapped during spring migration of 2010 at two localities in the central Mediterranean Sea. AP DNA was detected by PCR (gltA and 16S rRNA) and variant determination was performed using ankA sequences. In total, 358 ticks were collected. One of 19 ticks determined as Ixodes was confirmed positive for AP DNA. The tick was collected from a woodchat shrike (Lanius senator senator) trapped in Greece, and molecularly determined to belong to the I. ricinus complex and sharing highest (95%) 16S RNA sequence identity to I. gibbosus. The ankA AP sequence exhibited highest similarity to sequences from rodents and shrews (82%) and ruminants (80%). Phylogenetic analyses placed it convincingly outside other clades, suggesting that it represents a novel AP variant. The divergent Ixodes species harboring a novel AP variant could either indicate an enzootic cycle involving co-evolution with birds, or dissemination from other regions by avian migration. None of the 331 Hyalomma marginatum sensu lato ticks, all immature stages, were positive for AP DNA, lending no evidence for the involvement of Hyalomma ticks transported by birds in the ecology of AP.

A small molecule binds to a disordered protein in its monomeric form, preventing its aggregation linked to Alzheimer’s disease., Disordered proteins are challenging therapeutic targets, and no drug is currently in clinical use that modifies the properties of their monomeric states. Here, we identify a small molecule (10074-G5) capable of binding and sequestering the intrinsically disordered amyloid-β (Aβ) peptide in its monomeric, soluble state. Our analysis reveals that this compound interacts with Aβ and inhibits both the primary and secondary nucleation pathways in its aggregation process. We characterize this interaction using biophysical experiments and integrative structural ensemble determination methods. We observe that this molecule increases the conformational entropy of monomeric Aβ while decreasing its hydrophobic surface area. We also show that it rescues a Caenorhabditis elegans model of Aβ-associated toxicity, consistent with the mechanism of action identified from the in silico and in vitro studies. These results illustrate the strategy of stabilizing the monomeric states of disordered proteins with small molecules to alter their behavior for therapeutic purposes.

BackgroundThe common tickIxodes ricinusand the taiga tickI. persulcatusare the main tick vectors ofBorreliaspirochaetes, TBE virus (TBEV) and of several other zoonotic pathogens in the western and eastern areas, respectively of the Palaearctic region. Recently, populations of the taiga tick were, for the first time, detected in northern Sweden. This prompted us to investigate if they harbour human pathogens.MethodsA total of 276I. persulcatusticks (136 males, 126 females and 14 nymphs) and oneI. ricinusnymph was collected by the cloth-dragging method in northern Sweden in July–August 2015 and May–July 2016. In addition, 8 males and 10 females ofI. persulcatuswere collected from two dogs (16 and 2 ticks, respectively) in two of the localities. All ticks were microscopically and molecularly identified to developmental stage and species and screened forB. burgdorferi(sensu lato),B. miyamotoi,Anaplasma phagocytophilum,Rickettsiaspp., Neoehrlichia mikurensis,Babesiaspp. and TBEV using real-time PCR followed by species identification by sequencing the PCR-products of conventional PCR assays.ResultsOf the ticks collected by the cloth-dragging method, 55% (152/277) were positive forBorrelia. There was no significant difference between the proportions ofBorrelia-infected nymphs (33%, 5/15) andBorrelia-infected adult ticks (56%, 147/262), and no significant difference between the proportions ofBorrelia-infected males (54%, 74/136) andBorrelia-infected females (58%, 73/126). Three differentBorreliaspecies were identified.Borrelia afzeliiwas the predominant species and detected in 46% of allBorrelia-infected ticks followed byB. garinii, 35%,B. valaisiana, 1%, and mixed infections of differentBorreliaspecies, 1%; 17% of allBorrelia-infections were untypeable. OneI. persulcatusfemale containedRickettsia helvetica, and one nymph containedRickettsiasp. Of the 277 ticks analysed, all were negative forA. phagocytophilum,Babesiaspp.,Borrelia miyamotoi,N. mikurensisand TBEV. The ticks collected from the two dogs were negative for all pathogens examined except forBorreliaspp., that was detected in 5 out of 16 ticks removed from one of the dogs.ConclusionsTo our knowledge, this is the first time thatI. persulcatusfrom Sweden has been analysed for the presence of tick-borne pathogens. The examined tick populations had a low diversity of tick-borne pathogens but a high prevalence ofB. burgdorferi(s.l.).

Four species of the Anopheles maculipennis complex have previously been recorded in Sweden. A recent addition to the complex is Anopheles daciae, which is considered to be closely related to, but distinct from Anopheles messeae. The original designation of An. daciae was based on five genetic differences (161, 165, 167, 362 and 382) in the second internal transcribed spacer (ITS) 2 of the ribosomal RNA. Further studies have shown that only two nucleotide differences (362 and 382) robustly separate the species. Thirty-three An. maculipennis complex mosquitoes were collected in the province of Uppland, Sweden. All were An. daciae but showed double peaks for three variable positions (161, 165 and 167). When cloned, the intra-individual nucleotide variation was almost exclusively fixed with either TTC or AAT, originally diagnostic for An. messae and An. daciae, respectively. To further investigate the intra-individual variation, nine An. daciae and 11 An. messeae were collected in southern Sweden and their ITS2 fragments were amplified and sequenced using Illumina MiSeq sequencing (Illumina, Inc., San Diego, CA, USA). For the diagnostic nucleotide 382 no intra-individual variation could be detected. However, although each An. daciae specimen carried several ITS2 sequence variants for the four other nucleotides, there was no intra-individual variation in the An. messeae specimens.

Disordered proteins are challenging therapeutic targets, and no drug is currently in clinical use that has been shown to modify the properties of their monomeric states. Here, we identify a small molecule capable of binding and sequestering the amyloid-β peptide (Aβ) in its monomeric, soluble state. Our analysis reveals that this compound interacts with Aβ and inhibits both the primary and secondary nucleation pathways in its aggregation process. We characterise this interaction using biophysical experiments and integrative structural ensemble determination methods. We thus observe that this small molecule has the remarkable effect of increasing the conformational entropy of monomeric Aβ while decreasing its hydrophobic surface area. We then show that this small molecule rescues a Caenorhabditis elegans model of Aβ-associated toxicity in a manner consistent with the mechanism of action identified from the in silico and in vitro studies. These results provide an illustration of the strategy of targeting the monomeric states of disordered proteins with small molecules to alter their behaviour for therapeutic purposes.

Calcium ions regulate mitochondrial ATP production and contractile activity and thus play a pivotal role in matching energy supply and demand in cardiac muscle. Little is known about the magnitude and kinetics of the changes in free mitochondrial calcium concentration in cardiomyocytes. Using adenoviral infection, a ratiometric mitochondrially-targeted FRET-based calcium indicator (4 mtD3cpv, MitoCam) was expressed in cultured adult rat cardiomyocytes and the free mitochondrial calcium concentration ([Ca2+]m) was measured at different stimulation frequencies (0.1-4 Hz) and external calcium concentrations (1.8-3.6 mM) at 37°C. Cytosolic calcium concentrations were assessed under the same experimental conditions in separate experiments using Fura-4AM. The increases in [Ca2+]m during electrical stimulation at 0.1 Hz were rapid (rise time = 49 ± 2 ms), while the decreases in [Ca2+]m occurred more slowly (decay half time = 1.17 ± 0.07 s). Model calculations confirmed that this asymmetry caused the rise in [Ca2+]m during diastole observed at elevated stimulation frequencies. Inhibition of the mitochondrial sodium-calcium exchanger (mNCE) resulted in a rise in [Ca2+]m at baseline and -paradoxically- in an acceleration of Ca2+-release. In conclusion: rapid increases in [Ca2+]m allow for fast adjustment of mitochondrial ATP production to increases in myocardial demand on a beat-to-beat basis and mitochondrial calcium release depends on mNCE activity and mitochondrial calcium buffering. This article is protected by copyright. All rights reserved

From July 2018 to January 2019 we recorded 41 specimens of adult Hyalomma ticks, which had been found on horses, cattle or humans in 14 Swedish provinces. In 20 cases we received tick specimens, which were identified morphologically as adults of H. marginatum (n = 11) or H. rufipes (n = 9). These are the first documented records in Sweden of adults of H. marginatum and H. rufipes. Molecular tests for Crimean-Congo haemorrhagic fever virus and piroplasms (Babesia spp. and Theileria spp.) proved negative; 12 out of 20 tested specimens were positive for rickettsiae (R. aeschlimannii was identified in 11 of the ticks). All ticks originated from people or animals that had not been abroad during the previous two months. These data suggest (i) that the adult Hyalomma ticks originated from immature ticks, which had been brought from the south by migratory birds arriving in Sweden during spring or early summer; and that (ii) due to the exceptionally warm summer of 2018 these immature ticks had been able to develop to the adult stage in the summer and/or autumn of the same year. The rapidly changing climate most likely now permits these two Hyalomma species to develop to the adult, reproductive stage in northern Europe. There is consequently a need to revise the risk maps on the potential geographic occurrence of relevant tick species and related tick-borne pathogens in Sweden and in the neighbouring countries.

Protein aggregation has been implicated in many medical disorders, including Alzheimer’s and Parkinson’s diseases. Potential therapeutic strategies for these diseases propose the use of drugs to inhibit specific molecular events during the aggregation process. However, viable treatment protocols require balancing the efficacy of the drug with its toxicity, while accounting for the underlying events of aggregation and inhibition at the molecular level. To address this key problem, we combine here protein aggregation kinetics and control theory to determine optimal protocols that prevent protein aggregation via specific reaction pathways. We find that the optimal inhibition of primary and fibril-dependent secondary nucleation require fundamentally different drug administration protocols. We test the efficacy of our approach on experimental data for the aggregation of the amyloid- [Formula: see text] (1-42) peptide of Alzheimer’s disease in the model organism Caenorhabditis elegans. Our results pose and answer the question of the link between the molecular basis of protein aggregation and optimal strategies for inhibiting it, opening up avenues for the design of rational therapies to control pathological protein aggregation.

Alkhurma hemorrhagic fever virus RNA was detected in immature Hyalomma rufipes ticks infesting northward migratory birds caught in the North Mediterranean Basin. This finding suggests a role for birds in the ecology of the Alkhurma hemorrhagic fever virus and a potential mechanism for dissemination to novel regions. Increased surveillance is warranted.

Background The tick species Ixodes ricinus and I. persulcatus are of exceptional medical importance in the western and eastern parts, respectively, of the Palaearctic region. In Russia and Finland the range of I. persulcatus has recently increased. In Finland the first records of I. persulcatus are from 2004. The apparent expansion of its range in Finland prompted us to investigate if I. persulcatus also occurs in Sweden. Methods Dog owners and hunters in the coastal areas of northern Sweden provided information about localities where ticks could be present. In May-August 2015 we used the cloth-dragging method in 36 localities potentially harbouring ticks in the Bothnian Bay area, province Norrbotten (NB) of northern Sweden. Further to the south in the provinces Västerbotten (VB) and Uppland (UP) eight localities were similarly investigated. Results Ixodes persulcatus was detected in 9 of 36 field localities in the Bothnian Bay area. Nymphs, adult males and adult females (n = 46 ticks) of I. persulcatus were present mainly in Alnus incana - Sorbus aucuparia - Picea abies - Pinus sylvestris vegetation communities on islands in the Bothnian Bay. Some of these I. persulcatus populations seem to be the most northerly populations so far recorded of this species. Dog owners asserted that their dogs became tick-infested on these islands for the first time 7–8 years ago. Moose (Alces alces), hares (Lepus timidus), domestic dogs (Canis lupus familiaris) and ground-feeding birds are the most likely carriers dispersing I. persulcatus in this area. All ticks (n = 124) from the more southern provinces of VB and UP were identified as I. ricinus. Conclusions The geographical range of the taiga tick has recently expanded into northern Sweden. Increased information about prophylactic, anti-tick measures should be directed to people living in or visiting the coastal areas and islands of the Baltic Bay. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1658-3) contains supplementary material, which is available to authorized users.

A total of 887 adult Ixodes ricinus ticks (469 females and 418 males) from 29 different localities in Sweden were screened for Rickettsia , Anaplasma , and Coxiella DNA using PCR and then subjected to gene sequencing. Rickettsial DNA was detected in 9.5–9.6% of the ticks. Most of the positive ticks were infected with Rickettsia helvetica . One tick harbored another spotted fever rickettsia, closely related to or identical with R. sibirica not previously found in I. ricinus nor in Sweden. Six of the ticks (0.7%) were infected with an Anaplasma sp., presumably A. phagocytophilum . Coxiella burnetii DNA was not detected in any of the ticks. The detection of R. helvetica and A. phagocytophilum in several of the localities sampled suggests that these potentially human-pathogenic agents are common in Sweden.

During the last decade, much research on control strategies against the primary vector,Ixodes scapularis, of Lyme disease in northeastern USA has been carried out. This has included work on biological or chemical control, habitat modification, and reduction of host availability. In this paper we evaluate the possibility of using these methods for control of the primary vector of Lyme borreliosis in Sweden,I. ricinus. It is emphasized that in Sweden people mainly contract Lyme borreliosis in woodlands and forests. Because of the enormous size of the area that would need treatment, general application of acaricides and habitat modification may not work well in Sweden. Another possible method is to reduce the availability of tick hosts. This method can be targeted at species that are essential for tick reproduction or at hosts that are capable of infecting ticks withBorrelia burgdorferi. On isolated Swedish islands where few mammal species are present, reduction of the main or only reservoir host may effectively control Lyme borreliosis. On the Swedish mainland, however, at least four common mammal species are important blood-hosts to femaleI. ricinus, and at least eight common mammal species are competent reservoirs forB. burgdorferi. Sufficient reduction of host availability may therefore not be achieved here without killing vast numbers of mammals. In general in Sweden, the most effective method of preventing Lyme borreliosis seems to be to inform people about how to dress in risk areas, and that daily checks for ticks with prompt removal of attached ticks drastically reduces the infection risk.

Hematophagous parasites such as leeches, ticks, mites, lice, bedbugs, mosquitoes, and myiasis-producing fly larvae are common health problems in Lao People's Democratic Republic. Several arthropod-borne infections, e.g., malaria, dengue fever, and Japanese encephalitis, are endemic there. Effective vector control methods including the use of pesticides, insecticide-treated bed nets, and synthetic and plant-based repellents are important means of control against such invertebrates and the pathogens they may transmit or directly cause. In this study, we documented traditional knowledge on plants that are used to repel or kill hematophagous arthropods, including mosquitoes, bedbugs, human lice, mites and ticks, fly larvae, and blood-sucking leeches. Structured interviews were carried out in 66 villages comprising 17 ethnic groups, covering a range of cultures, throughout Lao People's Democratic Republic. A total of 92 plant species was recorded as traditional repellents (including plants for pesticidal usages) in 123 different plant-ectoparasite combinations. The number and species of plants, and animal taxa repelled (or killed) per plant species differed per region, village, and ethnic group. Traditional use was confirmed in the scientific literature for 74 of these plant species, and for an additional 13 species using literature on closely related species. The use of botanical repellents and pesticides from many plant species is common and widespread in the Lao countryside. In the future, the identification of the active components in certain plants to develop more optimal, inexpensive repellents, insecticides, acaricides, or antileech compounds as alternatives to synthetic repellents/pesticides against blood-feeding insects, ticks, mites, and leeches is warranted.

The toxicity of para-menthane-3,8-diol (PMD), the main arthropod-repellent compound in the oil of the lemon eucalyptus, Corymbia citriodora, was evaluated against nymphs of Ixodes ricinus using five methods (A-E) of a contact toxicity bioassay. Mortality rates were estimated by recording numbers of dead nymphs at 30 min intervals during the first 5 h after the start of exposure and at longer intervals thereafter. The mortality rate increased with increasing concentration of PMD and duration of exposure with a distinct effect after 3.5 h. From the results obtained by methods A, C and E, the LC(50) range was 0.035-0.037 mg PMD/cm(2) and the LC(95) range was 0.095-0.097 mg PMD/cm(2) at 4 h of exposure; the LT(50) range was 2.1-2.8 h and the LT(95) range was 3.9-4.2 h at 0.1 mg PMD/cm(2). To determine the duration of toxic activity of PMD, different concentrations (0.002, 0.01, 0.1 mg PMD/cm(2)) were tested and mortality was recorded at each concentration after 1 h; thereafter new ticks were tested. This test revealed that the lethal activity of PMD remained for 24 h but appeared absent after 48 h. The overall results show that PMD is toxic to nymphs of I. ricinus and may be useful for tick control.

The repellent effect of the essential oils of flower heads of the aromatic plant tansy, Tanacetum vulgare L. (Asteraceae), originating from Sweden, was tested against host-seeking nymphs of the common tick Ixodes ricinus (L.). The essential oils were obtained by steam distillation (SD) and by using an online solvent extraction separation setup. Further fractionations of the SD oils were obtained by medium-pressure liquid chromatography on silica gel. The volatiles of the essential oils and the fractions that exhibited strong tick repellency (90-100%) were collected by solid phase microextraction and identified by gas chromatography-mass spectrometry. The chemical analyses of the oils show that the populations of T. vulgare from Uppsala and Stockholm may represent different chemotypes, but that they exhibited similar tick repellency. Main volatiles detected from oils of T vulgare collected at Uppsala were a-pinene (27%), beta-pinene (11%), pinocamphone (11%), 1,3,3-trimethylcyclohex-l-ene-4-carboxaldehyde (11%), and 1,8-cineole (10%). In the sample collected in Stockholm, the main components were beta-thujone (39%) and camphor (23%) followed by a-thujone (11%) and 1,8-cineole (8%). When constituents in the oils, e.g., alpha-terpineol, 4-terpineol, alpha + beta-thujone, 1,8-cineol, verbenol, and verbenone, were tested separately (each diluted 0.5%, vol:vol), 64-72% tick repellency was obtained.

It is increasingly recognized that molecular chaperones play a key role in modulating the formation of amyloid fibrils, a process associated with a wide range of human disorders. Understanding the detailed mechanisms by which they perform this function, however, has been challenging because of the great complexity of the protein aggregation process itself. In this work, we build on a previous kinetic approach and develop a model that considers pairwise interactions between molecular chaperones and different protein species to identify the protein components targeted by the chaperones and the corresponding microscopic reaction steps that are inhibited. We show that these interactions conserve the topology of the unperturbed reaction network but modify the connectivity weights between the different microscopic steps. Moreover, by analysing several protein-molecular chaperone systems, we reveal the striking diversity in the microscopic mechanisms by which molecular chaperones act to suppress amyloid formation., Nature Communications, 7, ISSN:2041-1723

The dynamic nature of supramolecular polymers has a key role in their organization. Yet, the manipulation of their dimensions and polarity remains a challenge. Here, the minimalistic diphenylalanine building block was applied to demonstrate control of nano-assemblies growth and shrinkage using microfluidics. To fine-tune differential local environments, peptide nanotubes were confined by micron-scale pillars and subjected to monomer flows of various saturation levels to control assembly and disassembly. The small-volume device allows the rapid adjustment of conditions within the system. A simplified kinetic model was applied to calculate parameters of the growth mechanism. Direct real-time microscopy analysis revealed that different peptide derivatives show unidirectional or bidirectional axial dimension variation. Atomistic simulations show that unidirectional growth is dictated by the differences in the axial ends, as observed in the crystalline order of symmetry. This work lays foundations for the rational control of nano-materials dimensions for applications in biomedicine and material science., The organization of supramolecular peptide polymers determines their properties; however, controlling their dimensions still remains a problem. Here, Gazit et al. show the spontaneous elongation and shortening of these polymers at an individual nano-assembly level by using a microfluidic platform.

In our search for tick repellents of plant origin, to be used as alternatives to commercial arthropod repellents, we investigated the effect of the well known plant signaling compound methyl jasmonate (MJ) using nymphs of the tick Ixodes ricinus. In laboratory tests, pieces of cloth with MJ at 0.075, 0.15, 0.30 and 0.75 mg/cm2 yielded increasing repellencies against the nymphs: 57%, 71%, 92% and 99%, respectively, of the nymphs did not cling to the cloth. Repellency of MJ was also investigated in a tick-infested woodland area in central Sweden. Cotton flannel cloths sprayed with 0.05, 0.1 or 0.2 mg/cm2 MJ dissolved in acetone were dragged over the ground vegetation. The numbers of nymphs on the treated cloths were significantly lower than those on the untreated cloth. Thus, MJ has, at the concentrations tested, significant repellent activity against I. ricinus nymphs.

A number of different proteins possess the ability to polymerize into filamentous structures. Certain classes of such assemblies can have key functional roles in the cell, such as providing the structural basis for the cytoskeleton in the case of actin and tubulin, while others are implicated in the development of many pathological conditions, including Alzheimer's and Parkinson's diseases. In general, the fragmentation of such structures changes the total number of filament ends, which act as growth sites, and hence is a key feature of the dynamics of filamentous growth phenomena. In this paper, we present an analytical study of the master equation of breakable filament assembly and derive closed-form expressions for the time evolution of the filament length distribution for both open and closed systems with infinite and finite monomer supply, respectively. We use this theoretical framework to analyse experimental data for length distributions of insulin amyloid fibrils and show that our theory allows insights into the microscopic mechanisms of biofilament assembly to be obtained beyond those available from the conventional analysis of filament mass only.

In the field in south-central Sweden, we tested by randomised, standardised methodology the potential anti-tick repellent activity of two concentrations of MyggA Natural spray (containing PMD) (4.2 and 3.2 g/m2) and one of RB86 (with 70% neem oil containing azadirachtin) (3 g/m2) to host seeking nymphs of Ixodes ricinus. Each substance was applied separately to 1 m2 cotton flannel cloths. Nymphal ticks on the cloths, pulled over the vegetation, were recorded at 10-m stops. Nymphal numbers recorded differed significantly between treated cloths [4.2 or 3.2 g MyggA Natural spray/m2 and 3 g RB86/m2] and the untreated control (df = 3, chi2 = 112.74, P0.0001). Nymphal numbers also differed significantly among collectors (df = 3, chi2 = 15.80, P0.001). Repellency of treated cloths, i.e., 4.2 or 3.2 g MyggA Natural spray/m2 and 3 g RB 86/m2 declined from day 0 (i.e. the day of impregnation) to day 3 after impregnation from 77 to 24%, 58 to 16% and 47 to 0.5%, respectively. This study suggests that all three treatments have significant repellent activities against I. ricinus nymphs.

Leaves of Myrica gale Linnaeus (Myricaceae), Rhododendron tomentosum (Stokes) H. Harmaja (formerly Ledum palustre Linnaeus: Ericaceae) and Artemisia absinthium Linnaeus (Asteraceae) were extracted with organic solvents of different polarities and the essential oils of leaves were obtained by steam distillation. The extracts or oils were tested in the laboratory for repellency against host-seeking nymphs of Ixodes ricinus Linnaeus (Acari: Ixodidae). Rhododendron tomentosum oil, 10%, diluted in acetone, exhibited 95% repellency; R. tomentosum and A. absinthium extracts in ethyl acetate, > 70% repellency; A. absinthium extract in hexane, approximately 62% repellency; and M. gale oil, 10%, approximately 50% repellency on I. ricinus nymphs. Compounds in the leaf extracts or in the oils were collected by solid phase microextraction (SPME) and identified by gas chromatography-mass spectrometry (GC-MS) and/or MS. Characteristic volatiles detected from oil or extract of M. gale were the monoterpenes 1,8-cineole, alpha-terpineol, 4-terpineol and thujenol; and of R. tomentosum myrcene and palustrol. Characteristic volatiles from leaf extracts of A. absinthium were sabinene, oxygenated monoterpenes, e.g. thujenol and linalool, and geranyl acetate. Each plant species synthesized numerous volatiles known to exhibit acaricidal, insecticidal, 'pesticidal' and/or arthropod repellent properties. These plants may be useful sources of chemicals for the control of arthropods of medical, veterinary or agricultural importance.

Environmental risk factors associated with increased malaria mosquito (Anopheles) abundance indoors were studied in a suburban area, Antula, of Guinea Bissau, during the rainy seasons of 1993-1995. All bedrooms in 30 houses were searched for resting mosquitoes three times each year. The most abundant mosquito was An. gambiae s.s. Significantly greater numbers of resting mosquitoes were present in rooms with open eaves and in houses with a well on the compound. Pigs were the most common domestic animals in Antula. Presence of pigs in a house was associated with increased mosquito abundance in the bedrooms of the same house. The abundance of female mosquitoes also increased with increasing human biomass per square meter of bedroom area.

The colonization capacity and dispersal of sylvatic populations of Triatoma ryckmani Zeledón and Ponce were investigated by means of experimental chicken coops installed within the semiarid region in the Department of El Progreso, Guatemala. In the four artificial habitats a total of 672 T. ryckmani was found as well as two males of T. dimidiata (Latreille). Triatomine densities were not the same in the four chicken coops. From one chicken coop 53.4% (359) of the triatomines were collected. Full colonization, i.e. all stages from egg to adult found at the same time, took place in the fourth month after the first female's arrival. High dispersal and colonization capacity of T. ryckmani was evident; adult dispersal occurs mainly during the dry and coolest season (November-February). The overall female/male sex ratio was 2:1; more females than males were found throughout the year. Most of the triatomines in the shelter inside the chicken coops were found on the northern (43%; with less heat and sunlight) and eastern side (35%; more windy). This is the first report on the colonization capacity and population dynamics of T. ryckmani in artificial habitats in a Chagas disease endemic area of Central America.

In the summer of 1998 a forensic entomology project was carried out at the Unit of Forensic Medicine and the Department of Systematic Zoology at Uppsala University. This was the first forensic entomology project in Sweden. Arthropods were collected from corpses brought to the Unit of Forensic Medicine for autopsy. The arthropods were determined to species and developmental stage. Larvae of the blow flies (Diptera: Calliphoridae) Calliphora vicina Robineau-Desvoidy and Lucilia sericata (Meigen), and the beetle (Coleoptera: Dermestidae) Dermestes lardarius L. were recorded. The estimated ambient mean temperatures, development stages of the insects, and literature records of their developmental times were used to extrapolate the dates of death and thereby the post-mortem intervals (PMIs). The PMIs obtained by our data corresponded well with the PMIs obtained by other data.

International audience; Metal ions and their interaction with the amyloid beta (A) peptide might be key elements in the development of Alzheimer's disease. In this work the effect of Cu-II on the aggregation of A is explored on a timescale from milliseconds to days, both at physiological pH and under mildly acidic conditions, by using stopped-flow kinetic measurements (fluorescence and light-scattering), H-1 NMR relaxation and ThT fluorescence. A minimal reaction model that relates the initial Cu-II binding and A folding with downstream aggregation is presented. We demonstrate that a highly aggregation prone ACu(II) species is formed on the sub-second timescale at mildly acidic pH. This observation might be central to the molecular origin of the known detrimental effect of acidosis in Alzheimer's disease.

Candidatus Neoehrlichia mikurensis (CNM; family Anaplasmataceae) was recently recognized as a potential tick-borne human pathogen. The presence of CNM in mammals, in host-seeking Ixodes ticks and in ticks attached to mammals and birds has been reported recently. We investigated the presence of CNM in ornithophagous ticks from migrating birds. A total of 1,150 ticks (582 nymphs, 548 larvae, 18 undetermined ticks and two adult females) collected from 5,365 birds captured in south-eastern Sweden was screened for CNM by molecular methods. The birds represented 65 different species, of which 35 species were infested with one or more ticks. Based on a combination of morphological and molecular species identification, the majority of the ticks were identified as Ixodes ricinus. Samples were initially screened by real-time PCR targeting the CNM 16S rRNA gene, and confirmed by a second real-time PCR targeting the groEL gene. For positive samples, a 1260 base pair fragment of the 16S rRNA gene was sequenced. Based upon bacterial gene sequence identification, 2.1% (24/1150) of the analysed samples were CNM-positive. Twenty-two out of 24 CNM-positive ticks were molecularly identified as I. ricinus nymphs, and the remaining two were identified as I. ricinus based on morphology. The overall CNM prevalence in I. ricinus nymphs was 4.2%. None of the 548 tested larvae was positive. CNM-positive ticks were collected from 10 different bird species. The highest CNM-prevalences were recorded in nymphs collected from common redpoll (Carduelis flammea, 3/7), thrush nightingale (Luscinia luscinia, 2/29) and dunnock (Prunella modularis, 1/17). The 16S rRNA sequences obtained in this study were all identical to each other and to three previously reported European strains, two of which were obtained from humans. It is concluded that ornithophagous ticks may be infected with CNM and that birds most likely can disperse CNM-infected ticks over large geographical areas. Funding for this study came from the Medical Research Council of Southeast Sweden (grant numbers FORSS-307591 and FORSS-387231), Carl Trygger's Foundation for Scientific Research, Langmanska kulturfonden, Magnus Bergvall's Foundation for Scientific Research, Helge Ax:son Johnson's Foundation and the EU Interreg IVA project ScandTick.

We have with great interest read the paper by Tuuminen et al. ([1][1]) published in the July 2014 issue of this journal where the pine weevil (Hylobius abietis) is incriminated as a vector of the potential human pathogen Capnocytophaga canimorsus. The authors base their conclusion on the fact that

Background: A few billion birds migrate annually between their breeding grounds in Europe and their wintering grounds in Africa. Many bird species are tick-infested, and as a result of their innate migratory behavior, they contribute significantly to the geographic distribution of pathogens, including spotted fever rickettsiae. The aim of the present study was to characterize, in samples from two consecutive years, the potential role of migrant birds captured in Europe as disseminators of Rickettsia-infected ticks. Methods: Ticks were collected from a total of 14,789 birds during their seasonal migration northwards in spring 2009 and 2010 at bird observatories on two Mediterranean islands: Capri and Antikythira. All ticks were subjected to RNA extraction followed by cDNA synthesis and individually assayed with a real-time PCR targeting the citrate synthase (gltA) gene. For species identification of Rickettsia, multiple genes were sequenced. Results: Three hundred and ninety-eight (2.7%) of all captured birds were tick-infested; some birds carried more than one tick. A total number of 734 ticks were analysed of which 353 +/- 1 (48%) were Rickettsia-positive; 96% were infected with Rickettsia aeschlimannii and 4% with Rickettsia africae or unidentified Rickettsia species. The predominant tick taxon, Hyalomma marginatum sensu lato constituted 90% (n = 658) of the ticks collected. The remaining ticks were Ixodes frontalis, Amblyomma sp., Haemaphysalis sp., Rhipicephalus sp. and unidentified ixodids. Most ticks were nymphs (66%) followed by larvae (27%) and adult female ticks (0.5%). The majority (65%) of ticks was engorged and nearly all ticks contained visible blood. Conclusions: Migratory birds appear to have a great impact on the dissemination of Rickettsia-infected ticks, some of which may originate from distant locations. The potential ecological, medical and veterinary implications of such Rickettsia infections need further examination.

Ticks were collected from pastures and domestic and wild vertebrates during the rainy seasons of 1994 and 1996 in Guinea-Bissau. We collected the following species: from pastures Rhipicephalus lunulatus Neumann, R. muhsamae Morel & Vassiliades, R. senegalensis Koch, and R. sulcatus Neumann; from reptiles Amblyomma nuttalli Donitz and Aponomma flavomaculatum (Lucas); and from mammals Amblyomma paulopunctatum Neumann, Amblyomma splendidum Giebel, Amblyomma variegatum (F.), Hyalomma truncatum Koch, R. muhsamae, R. sanguineus (Latreille), R. senegalensis, and R. sulcatus. New host records are as follows: Amblyomma nuttalli on Senegal flap shelled turtle (Cyclanorbis senegalensis Dumeril & Bibron), Aponomma flavomaculatum on West African dwarf crocodile (Osteolaemus tetraspis Cope), and R. sulcatus on bushbuck (Tragelaphus scriptus Pallas). We reviewed the literature for earlier records of ticks from Guinea-Bissau. The regional distributions of the 21 tick species hitherto recorded in Guinea-Bissau are listed.

In the present study further characterization of the amplified sequence of the citrate synthase gene of the spotted fever group Rickettsia isolated from Ixodes ricinus ticks in Sweden showed that it has 100% homology with the deposited sequence of the citrate synthase gene of Rickettsia helvetica . The restriction fragment length polymorphism (RFLP) pattern of an amplified 382-bp product of the citrate synthase sequence, defined by primers RpCS877 and RpCS1258, yielded fragments for our isolate that could be visualized as a double band that migrated at approximately 44 bp, another double band at 85 bp, and a single band at nearly 120 bp after digestion with the restriction enzyme Alu I. When calculating a theoretical PCR-RFLP pattern of the sequence of the citrate synthase gene of R. helvetica from the known positions where the Alu I enzyme cuts, we arrived at the same pattern that was obtained for our isolate, a pattern distinctly different from the previously published PCR-RFLP pattern for R. helvetica . Investigation of 125 living I. ricinus ticks showed a higher prevalence of rickettsial DNA in these ticks than we had found in an earlier study. Rickettsial DNA was detected by amplification of the 16S rRNA gene, for which a seminested primer system consisting of two oligonucleotide primer pairs was used. Of the 125 ticks, some were pooled, giving a total of 82 tick samples, of which 20 were found to be positive for the rickettsial DNA gene investigated. When considering the fact that some of the positive samples were pooled, the minimum possible prevalence in these ticks was 20 of 125 (16%) and the maximum possible prevalence was 46 of 125 (36.8%). These prevalence estimates conform to those of other studies of spotted fever group rickettsiae in hard ticks in Europe.

By standardized interviews of people in 23 rural villages, in the Oio region of Guinea Bissau, we collected data on which plant species and plant derived products or methods people use to reduce mosquito biting activity.The following plants were used to reduce numbers of mosquitoes indoors at night: fresh or smouldering Hyptis suaveolens Poit. (Lamiaceae), smoke of the bark of Daniellia oliveri Rolfe (Caesalpiniaceae), smoke of the infructescence of Elaeis guineensis Jacq. (Arecaceae), smoke of the seed capsules of Parkia biglobosa (Jacq.) Benth. (Mimosaceae), smoke of the leaves of Azadirachta indica A.Juss. (Meliaceae) and Eucalyptus sp. (Myrtaceae), fresh Ocimum canum Sims (Lamiaceae), and fresh Senna occidentalis (L.) Link (Caesalpiniaceae). In two field experiments we estimated the ‘repellent activity’ of certain of these plants and compared their efficacies with those of two commercially available mosquito repellents, i.e. ‘positive’ controls. In the first experiment we tested: smouldering H. suaveolens (85.4% repellency); fresh H. suaveolens (73.2%); burning of the bark of D. oliveri (74.7%); and smoke of the leaves of Eucalyptus (72.2%). In the second experiment we tested: smouldering H. suaveolens (83.6% repellency); fresh H. suaveolens (66.5%); burning of the bark of D. oliveri (77.9%); smoke of the leaves of A. indica (76.0%); smoke of the infructescence of E. guineensis (69.0%); fresh O. canum (63.6%); and fresh S. occidentalis; (29.4%). All the products tested, except S. occidentalis were significantly more effective than the negative control.

An analysis of cuticular hydrocarbons (CH) of unfed adult Ixodes ricinus ticks collected throughout Europe showed that there are 10 distinct I. ricinus groups. Studies on the seasonal and annual consistency of CH composition and possible effects of host and environmental factors suggested that CHs may be used as a genuine genetic marker for I. ricinus. Preliminary studies compared the vector competence of ticks from three of the most separated I. ricinus groups and the results suggested that there may be significant differences in tick susceptibility to Borrelia afzelii.

Background : Mosquitoes are the primary vectors of West Nile virus (WNV). Ticks have, however, been suggested to be potential reservoirs of WNV. In order to investigate their role in the spread of the virus, ticks, which had been collected from birds migrating northwards from Africa to Europe, were analyzed for the potential presence of WNV-RNA. Methods : On the Mediterranean islands Capri and Antikythira a total of 14,824 birds were captured and investigated from which 747 ticks were collected. Results and conclusions : Most of the identified ticks (93%) were nymphs and larvae of Hyalomma marginatum sensu lato, most of which were or appear to be Hyalomma rufipes. Of these ticks 729 were individually screened for WNV-RNA. None of the ticks was found to be WNV positive. Thus, there was no evidence that Hyalomma marginatum s.l. ticks play a role in the spread of WNV from Africa to Europe. Keywords : West Nile virus; emerging infectious diseases; migratory birds; zoonoses; ticks; Hyalomma marginatum s.l.; Hyalomma rufipes (Published: 15 January 2014) Citation: Infection Ecology and Epidemiology 2014, 4 : 20943 - http://dx.doi.org/10.3402/iee.v4.20943

Background: In northern Europe, the tick-borne encephalitis virus (TBEV) of the European subtype is usually transmitted to humans by the common tick Ixodes ricinus. The aims of the present study are (i) to obtain up-to-date information on the TBEV prevalence in host-seeking I. ricinus in southern and central Sweden; (ii) to compile and review all relevant published records on the prevalence of TBEV in ticks in northern Europe; and (iii) to analyse and try to explain how the TBE virus can be maintained in natural foci despite an apparently low TBEV infection prevalence in the vector population. Methods: To estimate the mean minimum infection rate (MIR) of TBEV in I. ricinus in northern Europe (i.e. Denmark, Norway, Sweden and Finland) we reviewed all published TBEV prevalence data for host-seeking I. ricinus collected during 1958–2011. Moreover, we collected 2,074 nymphs and 906 adults of I. ricinus from 29 localities in Sweden during 2008. These ticks were screened for TBEV by RT-PCR. Results: The MIR for TBEV in nymphal and adult I. ricinus was 0.28% for northern Europe and 0.23% for southern Sweden. The infection prevalence of TBEV was significantly lower in nymphs (0.10%) than in adult ticks (0.55%). At a well-known TBEV-endemic locality, Toro island south-east of Stockholm, the TBEV prevalence (MIR) was 0.51% in nymphs and 4.48% in adults of I. ricinus. Conclusions: If the ratio of nymphs to adult ticks in the TBEV-analysed sample differs from that in the I. ricinus population in the field, the MIR obtained will not necessarily reflect the TBEV prevalence in the field. The relatively low TBEV prevalence in the potential vector population recorded in most studies may partly be due to: (i) inclusion of uninfected ticks from the ‘uninfected areas’ surrounding the TBEV endemic foci; (ii) inclusion of an unrepresentative, too large proportion of immature ticks, compared to adult ticks, in the analysed tick pools; and (iii) shortcomings in the laboratory techniques used to detect the virus that may be present in a very low concentration or undetectable state in ticks which have not recently fed.

Infestation by Ixodes ricinus ticks on rodents, hares and cervids was examined at Bogesund, 10 km north of Stockholm, in south-central Sweden during 1991-1994 and on varying hares (Lepus timidus) at Stora Karlso and Gotska Sandon in the Baltic Sea during 1992-1993. At Bogesund, there were great differences between two consecutive years in the number of I. ricinus larvae infesting bank voles (Clethrionomys glareolus). The seasonal pattern of infestation by I. ricinus larvae and nymphs on bank voles was unimodal in 1991, with peaks in June-July and bimodal in 1992, with peaks in June and August. Male bank voles, compared to females and older voles, compared to young voles, harboured greater numbers of I. ricinus ticks. Apodemus mice, compared to bank voles, harboured greater numbers of I. ricinus ticks. Ixodes ricinus larvae engorged on Apodemus mice were heavier than larvae engorged on bank voles and resulted in larger nymphs. However, there was no difference in the proportions of viable nymphs resulting from larvae engorged on mice or voles. The ranges in the numbers of I. ricinus ticks infesting individual hosts were 1-451 for rodents, 16-2374 for hares and 428-2072 for roe deer (Capreolus capreolus). These ranges of tick numbers are estimated to represent potential blood losses from individual hosts of approximately 0.2-65% for rodents, 0.2-13% for hares and 0.3-9.0% for roe deer. Within the populations of all host species examined, the distributions of all stages of I. ricinus were clumped, with most host individuals harbouring few ticks and only a few individuals harbouring many ticks. The data suggest that, even though a small proportion of tick hosts may be severely affected, the direct effects of feeding by I. ricinus are unlikely to play an important role on mammal population dynamics.

The vertical distribution in the vegetation of questing Ixodes ricinus ticks was investigated in two different vegetation types (‘high’ and ‘low’ vegetation) at two localities in south-central Sweden during 1992-1993 (Toro) and 1995 (Bogesund). Significant correlations were found between the vertical distribution of immature ticks and the height of the vegetation. The greatest mean availabilities of the larvae and nymphs in low vegetation were in the intervals 0-9 and 30-39 cm, respectively. The larval numbers were greatest close to the ground (0-29 cm) in both high and low vegetation. The larval : nymphal ratio, at ground level at localities free of ground vegetation, varied between 8 : 1 and 32 : 1. In high vegetation, the greatest mean numbers of nymphal and adult ticks were at height intervals of 50-59 and 60-79 cm, respectively. These ranges are within the estimated height interval (40-100 cm) of the main part of the body surface of their ‘preferred’ host, the roe deer (Capreolus capreolus). The presence of most questing I. ricinus larvae at ground level would favour the transmission of Borrelia burgdorferi s.l., since this is where the highly reservoir-competent rodents and shrews usually occur.

We investigated isolated ecosystems to determine if Lyme borreliosis is maintained in the absence of reservoir-competent small mammals. Human cases of Lyme disease have been reported on the isolated islands of Gotska Sandön and Stora Karlsö in the Baltic Sea. The varying hare, Lepus timidus, is the only terrestrial vertebrate species capable of serving as a host for all stages of Ixodes ricinus (L.) on these islands. In August, mean larval infestation on 5 hares from each island was 548 with a maximum of 2,276 larvae on 1 hare. Smaller numbers of nymphal and female ticks were also engorging on the hares. During August-September, B. burgdorferi s.l. was detected in 11-24% of nymphal I. ricinus fed as larvae on hares and in 8-19% of host-seeking nymphal I. ricinus collected from the vegetation. We conclude that L. timidus serves as a maintenance host for B. burgdorferi s.l. and its vector, I. ricinus, on both islands.

For the first time, the reduviid bug Triatoma ryckmani Zeledon and Ponce (Hemiptera; Reduviidae) was recorded to inhabit the epiphyte Tillandsia xerographica Rohweder (Bromeliaceae) in the semiarid region of Guatemala. These bromeliads grow mainly in drought-resistant trees with rough bark such as Pereskia lychnidiflora (Cactaceae). In our study site, we investigated 30 T. xerographica, and 53 specimens of T. ryckmani were found. Most T. ryckmani (68.5%) were unfed. Ants (Formicidae) were the predominant (92.2%) insect taxon in T. xerographica. Other insects such as Blattidae (3.0%), Reduviidae (T. ryckmani: 2.5%), Blaberidae (2.2%), Gryllidae (0.1%), and Acrididae (0.1%) were recorded in the bromeliads. T. xerographica is illegally commercialized without previous inspection. This may cause accidental introduction of T. ryckmani to houses and to other countries.

BACKGROUND: The common tick Ixodes ricinus is the main vector in Europe of the tick-borne encephalitis virus and of several species of the Borrelia burgdorferi sensu lato complex, which are the etiological agents of Lyme borreliosis. The risk to contract bites of I. ricinus is dependent on many factors including the behaviour of both ticks and people. The tick's site of attachment on the human body and the duration of tick attachment may be of clinical importance. Data on I. ricinus ticks, which were found attached to the skin of people, were analysed regarding potentially stage-specific differences in location of attachment sites, duration of tick attachment (= feeding duration), seasonal and geographical distribution of tick infestation in relation to age and gender of the tick-infested hosts. METHODS: During 2008-2009, 1770 tick-bitten persons from Sweden and the Åland Islands removed 2110 I. ricinus ticks. Participants provided information about the date of tick detection and location on their body of each attached tick. Ticks were identified to species and developmental stage. The feeding duration of each nymph and adult female tick was microscopically estimated based on the scutal and the coxal index. RESULTS: In 2008, participants were tick-bitten from mid-May to mid-October and in 2009 from early April to early November. The infestation pattern of the nymphs was bimodal whereas that of the adult female ticks was unimodal with a peak in late summer. Tick attachment site on the human body was associated with stage of the tick and gender of the human host. Site of attachment seemed to influence the duration of tick feeding. Overall, 63% of nymphs and adult female ticks were detected and removed more than 24 hours after attachment. Older persons, compared to younger ones, and men, compared to women, removed "their" ticks after a longer period of tick attachment. CONCLUSIONS: The infestation behaviour of the different tick stages concerning where on the host's body the ticks generally will attach and when such ticks generally will be detected and removed in relation to host age and gender, should be of value for the development of prophylactic methods against tick infestation and to provide relevant advice to people on how to avoid or reduce the risk of tick infestation.

Lyme disease is a zoonosis transmitted by ticks and caused by the spirochete Borrelia burgdorferi sensu lato. Epidemiological and ecological investigations to date have focused on the terrestrial forms of Lyme disease. Here we show a significant role for seabirds in a global transmission cycle by demonstrating the presence of Lyme disease Borrelia spirochetes in Ixodes uriae ticks from several seabird colonies in both the Southern and Northern Hemispheres. Borrelia DNA was isolated from I. uriae ticks and from cultured spirochetes. Sequence analysis of a conserved region of the flagellin (fla) gene revealed that the DNA obtained was from B. garinii regardless of the geographical origin of the sample. Identical fla gene fragments in ticks obtained from different hemispheres indicate a transhemispheric exchange of Lyme disease spirochetes. A marine ecological niche and a marine epidemiological route for Lyme disease borreliae are proposed.

We determined the capacity of bank voles (Clethrionomys glareolus) to infect feeding Ixodes ricinus ticks with Borrelia burgdorferi sensu lato (infectivity), during June to October 1991 and June to September 1992 in south-central Sweden. In both years, the infectivity of older voles to ticks was higher in August to September (48% to 59%) than in June to July (20% to 32%). We propose that the infectivity of bank vole populations in Sweden decreases during winter and spring due to death of highly infective voles and recruitment of uninfective young ones, and that the tick vector, rather than the mammalian host, is the primary overwintering reservoir of B. burgdorferi.

Essential oils of Hyptis suaveolens (Lamiaceae), Croton roxburghii (Euphorbiaceae), and Litsea cubeba (Lauraceae) were tested in the field near Vientiane city, Lao PDR, on humans for repellent activity against mosquitoes. Landing mosquitoes were collected and later identified. The most abundant mosquitoes captured belonged to the genera Armigeres, Culex, and Aedes. All the plant oils tested at concentrations of 1.7 microg/cm(2), 3.3 microg/cm(2), and 6.3 microg/cm(2) were significantly more mosquito repellent than the negative control. Croton oil was significantly repellent against mosquitoes of the three genera at the highest (6.3 microg/cm(2)) concentration tested. Litsea oil was significantly repellent against Armigeres at all (1.7 microg/cm(2), 3.3 microg/cm(2), and 6.3 microg/cm(2)) concentrations tested. Hyptis oil was significantly repellent against Armigeres at 3.3 microg/cm(2) and 6.3 microg/cm(2) and against Culex at 1.7 microg/cm(2) and 6.3 microg/cm(2). The oils were analyzed for chemical content of volatiles, mainly terpenes. Main constituents were beta-pinene, sabinene, and 1,8-cineol from oils of the green parts of H. suaveolens; alpha-pinene, beta-pinene, and alpha-phellandrene from fresh bark of C. roxburghii; and alpha-pinene, beta-phellandrene, sabinene, and 1,8-cineol from fresh fruits of L. cubeba.