A virus becomes a global concern: research activities on West-Nile virus

Currently, West-Nile virus (WNV) is spreading worldwide to colder regions due to climate change. Human mortality and morbidity are prevalent and steadily increasing, associated with costs to public health systems. Therefore, the question of the impact of scientific engagement arises. What trends, barriers, and incentives for research related to global burdens are important in this context? To answer these questions, this study provides detailed insights into the publication patterns of WNV research and interprets them using several parameters, such as absolute and relative publication indices and socioeconomic and epidemiological characteristics. It is shown that national interests combined with regional outbreaks significantly influence publication intensity. Thus, a correlation between national publication volume and the number of WNV cases was observed. In contrast to most life science topics, the scientific interest in WNV significantly decreased after 2006. The USA, as the main actor in WNV research, is at the centre of international networking. Recently, European countries are also getting involved according to their new-emerging outbreaks. The results demonstrate national interest in research activities with a lack of globally focused approaches that are urgently needed to better understand and assess the distribution and characteristics of WNV.

dynamAedes: a unified modelling framework for invasive Aedes mosquitoes

Mosquito species belonging to the genus Aedes have attracted the interest of scientists and public health officers because of their capacity to transmit viruses that affect humans. Some of these species were brought outside their native range by means of trade and tourism and then colonised new regions thanks to a unique combination of eco-physiological traits. Considering mosquito physiological and behavioural traits to understand and predict their population dynamics is thus a crucial step in developing strategies to mitigate the local densities of invasive Aedes populations. Here, we synthesised the life cycle of four invasive Aedes species (Ae. aegypti, Ae. albopictus, Ae. japonicus and Ae. koreicus) in a single multi-scale stochastic modelling framework which we coded in the R package dynamAedes. We designed a stage-based and time-discrete stochastic model driven by temperature, photo-period and inter-specific larval competition that can be applied to three different spatial scales: punctual, local and regional. These spatial scales consider different degrees of spatial complexity and data availability by accounting for both active and passive dispersal of mosquito species as well as for the heterogeneity of the input temperature data. Our overarching aim was to provide a flexible, open-source and user-friendly tool rooted in the most updated knowledge on the species' biology which could be applied to the management of invasive Aedes populations as well as to more theoretical ecological inquiries.

A barcoding pipeline for mosquito surveillance in Nepal, a biodiverse dengue-endemic country

Background

Vector-borne diseases are on the rise on a global scale, which is anticipated to further accelerate because of anthropogenic climate change. Resource-limited regions are especially hard hit by this increment with the currently implemented surveillance programs being inadequate for the observed expansion of potential vector species. Cost-effective methods that can be easily implemented in resource-limited settings, e.g. under field conditions, are thus urgently needed to function as an early warning system for vector-borne disease epidemics. Our aim was to enhance entomological capacity in Nepal, a country with endemicity of numerous vector-borne diseases and with frequent outbreaks of dengue fever.

Methods

We used a field barcoding pipeline based on DNA nanopore sequencing (Oxford Nanopore Technologies) and verified its use for different mosquito life stages and storage methods. We furthermore hosted an online workshop to facilitate knowledge transfer to Nepalese scientific experts from different disciplines.

Results

The use of the barcoding pipeline could be verified for adult mosquitos and eggs, as well as for homogenized samples, dried specimens, samples that were stored in ethanol and frozen tissue. The transfer of knowledge was successful, as reflected by feedback from the participants and their wish to implement the method.

Conclusions

Cost effective strategies are urgently needed to assess the likelihood of disease outbreaks. We were able to show that field sequencing provides a solution that is cost-effective, undemanding in its implementation and easy to learn. The knowledge transfer to Nepalese scientific experts from different disciplines provides an opportunity for sustainable implementation of low-cost portable sequencing solutions in Nepal.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05255-1.

Genomic basis for drought resistance in European beech forests threatened by climate change

In the course of global climate change, Central Europe is experiencing more frequent and prolonged periods of drought. The drought years 2018 and 2019 affected European beeches (Fagus sylvatica L.) differently: even in the same stand, drought-damaged trees neighboured healthy trees, suggesting that the genotype rather than the environment was responsible for this conspicuous pattern. We used this natural experiment to study the genomic basis of drought resistance with Pool-GWAS. Contrasting the extreme phenotypes identified 106 significantly associated single-nucleotide polymorphisms (SNPs) throughout the genome. Most annotated genes with associated SNPs (>70%) were previously implicated in the drought reaction of plants. Non-synonymous substitutions led either to a functional amino acid exchange or premature termination. An SNP assay with 70 loci allowed predicting drought phenotype in 98.6% of a validation sample of 92 trees. Drought resistance in European beech is a moderately polygenic trait that should respond well to natural selection, selective management, and breeding.

Climate change is having a serious impact on many ecosystems. In the summer of 2018 and 2019, around two thirds of European beech trees were damaged or killed by extreme drought. It is critical to keep these beech woods healthy, as they are central to the survival of over 6,000 other species of animals and plants.

The level of damage caused by the drought varied between forests. However, not all the trees in each forest responded in the same way, with severely damaged trees often sitting next to fully healthy ones. This suggests that the genetic make-up of each tree determines how well it can adapt to drought rather than its local environment.

To investigate this further, Pfenninger et al. studied the genome of over 400 European beech trees from the Hesse region in Germany. The samples came from pairs of neighbouring trees that had responded differently to the droughts. The analysis found more than 80 parts of the genome that differed between healthy and damaged trees.

Pfenninger et al. then used this information to create a genetic test which can quickly and inexpensively predict how well an individual beech tree might survive in a drought. Applying this test to another 92 trees revealed that it can reliably detect which ones were healthy and which ones were damaged.

Beech forests are typically managed by private owners, agencies or breeders that could use this genetic test to select and reproduce trees that are better adapted to drought. The goal now is to develop the test so that it can be used more widely to manage European beech trees and potentially other species.

Knowledge on exotic mosquitoes in Germany, and public acceptance and effectiveness of Bti and two self-prepared insecticides against Aedes japonicus japonicus

Mosquito-borne diseases are a continuous challenge to public health. To prevent transmission, Integrated Vector Management (IVM) applies preventive, control, and communicational strategies that should be feasible, environmentally benign, and sustainable. IVM shows higher efficiency when being supported by local communities. Accordingly, we applied a social-ecological approach to identify the public acceptance of control measures and effectiveness of Eurocent coins containing copper, clove essential oil (EO) and Bacillus thuringiensis israelensis (Bti). We performed field and laboratory experiments to demonstrate the toxicity of alternative substances against Aedes japonicus japonicus. In expert interviews, we asked for (1) knowledge on exotic mosquitoes in Germany, (2) potential chances of alternative substances in future mosquito control, and (3) their needs for further clarification before application. We assessed potential users' (4) awareness of exotic mosquitoes and (5) willingness to apply the substances. Self-prepared copper coins and EO were clearly preferred by potential users over Bti. However, 100% mortality of the sensitive first stage could not be reached with the number of ten 5-Eurocent coins showing limited toxicity. Clove EO was shown to work as oviposition deterrent and larvicide with a LC50 of 17 mg l-1 (95% CI: 15-19 mg l-1). This study shows the importance of potential users' perspectives in IVM and the need for authorised insecticides.

Response to "How many species of giraffe are there?"

It is not unexpected that a proposal, such as ours [1], of four new mammalian species stirs up controversy, as evident in the correspondence by Bercovitch et al.[2]. We appreciate that their concerns are unrelated to the quality of the genetic data, the methodological approach or analyses, but are focused on the interpretation. Thus, we provided an analysis of giraffe speciation based on genomic sequence data, and not just "another viewpoint on giraffe taxonomy" [2]. We maintain our perspective that there is not only one but four species of giraffe (Figure 1).

Modelling seasonal dynamics, population stability, and pest control in Aedes japonicus japonicus (Diptera: Culicidae)

BACKGROUND

The invasive temperate mosquito Aedes japonicus japonicus is a potential vector for various infectious diseases and therefore a target of vector control measures. Even though established in Germany, it is unclear whether the species has already reached its full distribution potential. The possible range of the species, its annual population dynamics, the success of vector control measures and future expansions due to climate change still remain poorly understood. While numerous studies on occurrence have been conducted, they used mainly presence data from relatively few locations. In contrast, we used experimental life history data to model the dynamics of a continuous stage-structured population to infer potential seasonal densities and ask whether stable populations are likely to establish over a period of more than one year. In addition, we used climate change models to infer future ranges. Finally, we evaluated the effectiveness of various stage-specific vector control measures.

RESULTS

Aedes j. japonicus has already established stable populations in the southwest and west of Germany. Our models predict a spread of Ae. j. japonicus beyond the currently observed range, but likely not much further eastwards under current climatic conditions. Climate change models, however, will expand this range substantially and higher annual densities can be expected. Applying vector control measures to oviposition, survival of eggs, larvae or adults showed that application of adulticides for 30 days between late spring and early autumn, while ambient temperatures are above 9 °C, can reduce population density by 75%. Continuous application of larvicide showed similar results in population reduction. Most importantly, we showed that with the consequent application of a mixed strategy, it should be possible to significantly reduce or even extinguish existing populations with reasonable effort.

CONCLUSION

Our study provides valuable insights into the mechanisms concerning the establishment of stable populations in invasive species. In order to minimise the hazard to public health, we recommend vector control measures to be applied in 'high risk areas' which are predicted to allow establishment of stable populations to establish.

Larval superiority of Culex pipiens to Aedes albopictus in a replacement series experiment: prospects for coexistence in Germany

Background

The Asian tiger mosquito Aedes albopictus is an extremely invasive, globally distributed and medically important vector of various human and veterinary pathogens. In Germany, where this species was recently introduced, its establishment may become modulated by interspecific competition from autochthonous mosquito species, especially Culex pipiens (s.l.). While competitive superiority of Ae. albopictus to Cx. pipiens (s.l.) has been described elsewhere, it has not been assessed in the epidemiological conditions of Germany. The present study aimed to determine if such superiority exists under the physicochemical and microclimatic conditions typical for container habitats in Germany.

Methods

In a replacement series experiment, the larval and pupal responses of Ae. albopictus and Cx. pipiens (s.l.) (mortality, development time, growth) to interspecific interaction (five larval ratios) at (sub-)optimal temperatures (15, 20 and 25 °C) and differing food supply (3 and 6 mg animal-based food larva^-1) were investigated using a randomized split-plot design. In addition to physicochemical measurements of the test media, natural physicochemical conditions were determined for comparative analyses in mosquito breeding sites across the Rhine-Main metropolitan region of Germany.

Results

Under the physicochemical and microclimatic conditions similar to the breeding sites of the Rhine-Main region, competitive superiority of Cx. pipiens (s.l.) to Ae. albopictus in terms of larval survival was more frequently observed than balanced coexistence. Food regime and multifactorial interactions, but not temperature alone, were controlling factors for interspecific competition. Larval food regime and the larval ratio of Ae. albopictus influenced the physicochemistry and algal growth at 15 °C, with increased Ae. albopictus mortality linked to a decreasing number of Scenedesmus, Oocystis and Anabaena algae.

Conclusions

Under the present environmental conditions, the spread of Ae. albopictus from isolated foci in Germany may generally be slowed by biotic interactions with the ubiquitous Cx. pipiens (s.l.) (and potentially other container-breeding mosquito species) and by limnic microalgae in microhabitats with high resource levels. Detailed knowledge of the context dependency in temperate mosquito ecology, and interrelations of physicochemistry and phycology may help to achieve a better understanding of the upcoming Ae. albopictus colonization processes in central and northern Europe.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-2665-3) contains supplementary material, which is available to authorized users.

Glutamine attenuates leukocyte-endothelial cell adhesion in indomethacin-induced intestinal inflammation in the rat

BACKGROUND

Glutamine (Gln) is a major energy source for the intestinal mucosa. Its depletion results in epithelial atrophy and in bacterial translocation. Clinical substitution of this nonessential amino acid in critically ill persons results in a reduction of epithelial atrophy and in an accelerated recovery. The objective of this study was to assess the effect of Gln on leukocyte-endothelial cell interaction in an indomethacin (Indo)-induced long-lasting ileitis in Sprague-Dawley rats.

METHODS

Indo (7.5 mg/kg subcutaneously) was injected at time 0 and 24 hours later. Animals were fed with standard rat chow (ST) for 10 days until 12 hours before intravital microscopy analysis. Gln (3 g/kg body wt) was gavaged twice a day in the morning 4 hours apart (1) for 10 days between Indo administration and the experiment (ST/Gln, therapy), (2) for 14 days before Indo (Gln/ST, prophylaxis), or (3) from 14 days before Indo until the experiment (Gln/Gln, prophylaxis and therapy). Ten mesenteric venules (30 microm diameter) per animal (n = 5 per group) were observed using intravital microscopy, and the following parameters were monitored: number of adherent and emigrated leukocytes, leukocyte rolling velocity, erythrocyte velocity, venular blood flow, and shear rate. Macroscopically visible injury was scored 0 to 5.

RESULTS

Ten days after Indo treatment the macroscopic score was 3.5+/-0.4 vs. 0.6+/-0.2 of controls, and leukocyte adherence and emigration were increased (2.2-fold and 3.3-fold vs. control, respectively), whereas leukocyte rolling velocity and venular wall shear rate were reduced (both parameters to 81% of control). Glutamine prophylaxis, therapy, and the combination of both significantly attenuated macroscopic damage and prevented the microcirculatory disturbances to a similar extent. The beneficial effects of glutamine were accompanied by a normalization of fecal pH to control level, which had been lowered by Indo treatment.

CONCLUSIONS

The long-lasting Indo-induced ileitis was accompanied by macroscopic ulceration and microcirculatory disturbances. Oral therapy and prophylaxis with glutamine reduced macroscopic and microcirculatory inflammatory activity, indicating a special demand for glutamine in this type of inflammation.

Acute changes in vitamin B6 status in endurance athletes before and after a marathon

The vitamin B6 status of 13 endurance athletes was determined by whole blood B6 (microbiological) and urine 4-pyridoxic acid (4-PA) (HPLC), serum vitamin B6 (pyridoxal, pyridoxol, pyridoxamine) (HPLC), and erythrocyte alpha-EGOT measurements with the aid of 7-day records. In addition, blood and serum samples and urine were collected before (Time A), directly after (Time B), and 2 hr after a marathon race (Time C). The total energy intake was 12,303 +/- 3,464 kJ/day (34% fat, 48% carbohydrates, 14% protein). The vitamin B6 intake, serum concentrations, alpha-EGOT value, and 4-PA excretion were higher than the reference values at Time A. Only the vitamin B6 whole blood levels were below the normal level at Time A. The vitamin B6 status of the athletes corresponded essentially to reference values obtained for untrained individuals. There was a mean loss of about 1 mg vitamin B6 as a result of the marathon race. Vitamin B6 supplementation does not appear necessary if a balanced diet is consumed.

Assessment of vitamin B6 status of strength and speedpower athletes

OBJECTIVE

The investigation was designed to obtain information concerning the vitamin B6 status in high-performance athletes.

SUBJECTS

Fifty-seven strength and speedpower athletes were available for examination.

METHODS

Vitamin B6 status was determined by a 7-day weighed food record, enzyme activity (alpha-EGOT) measurement, whole blood concentrations (Saccharomyces carlsbergenisis and 4-pyridoxinic acid (4-PA) excretion (high-pressure liquid chromatography).

RESULTS

The absolute vitamin B6 intake in > 30% of the athletes was below the German recommended dietary allowance (GRDA) and, in relation to the protein intake (GRDA 0.20 mg vitamin B6/g protein), > 60% of the athletes had values below the GRDA. More than 90% of the athletes did not attain the reference value (0.88 nmol/mL) for untrained individuals in vitamin B6 whole blood concentration, and only a few athletes (< 5%) had alpha-EGOT values above the reference value of alpha-EGOT > 1.50). The 4-PA excretion was below the reference value of > 2.73 mumol/g creatinine in 18% of all athletes examined.

CONCLUSIONS

Vitamin B6 status can be quantified using the weighed food record, microbiological whole blood determination, and 4-PA excretion; however, limits of the individual methods must be taken into account. Vitamin B6 supply of the athletes still cannot be definitively assessed because there are no generally valid reference values.

[Pantothenic acid levels in blood of athletes at rest and after aerobic exercise]

Ninety-six high-performance athletes of various disciplines were available for this investigation. All athletes had many years of training and competition experience. The pantothenic acid contents in the blood were determined by means of microbiological measurements. In addition to the pantothenic acid level at rest, measurements were made resp. physical exertion in 14 marathon runners and nine body builders. Blood was collected for determination of pantothenic acid before (a), after (b) and 2 h after exercise. Compared to the reference values for untrained persons (1.34 +/- 0.13 nmol/mL), the marathon runners with 0.76 (0.31-0.94) nmol/mL and soccer players with 1.19 (0.37-2.64) nmol/mL were below the reference values. According to relative frequencies, more than 30% of all athletes were below the lower limit (< 1.20 nmol/mL). The values in body builders/racing cyclists differed significantly from those in marathon racers (p < 0.001), which is presumably due to unallowed supplementation. During exercise, there was a significant increase in the pantothenic acid level in marathon runners (p < 0.01).