Trachipleistophora extenrec n. sp. a new microsporidian (fungi: microsporidia) infecting mammals

Foodborne Diseases in the Edible Insect Industry in Europe-New Challenges and Old Problems

Insects play a key role in European agroecosystems. Insects provide important ecosystem services and make a significant contribution to the food chain, sustainable agriculture, the farm-to-fork (F2F) strategy, and the European Green Deal. Edible insects are regarded as a sustainable alternative to livestock, but their microbiological safety for consumers has not yet been fully clarified. The aim of this article is to describe the role of edible insects in the F2F approach, to discuss the latest veterinary guidelines concerning consumption of insect-based foods, and to analyze the biological, chemical, and physical hazards associated with edible insect farming and processing. Five groups of biological risk factors, ten groups of chemical risk factors, and thirteen groups of physical risks factors have been identified and divided into sub-groups. The presented risk maps can facilitate identification of potential threats, such as foodborne pathogens in various insect species and insect-based foods. Ensuring safety of insect-based foods, including effective control of foodborne diseases, will be a significant milestone on the path to maintaining a sustainable food chain in line with the F2F strategy and EU policies. Edible insects constitute a new category of farmed animals and a novel link in the food chain, but their production poses the same problems and challenges that are encountered in conventional livestock rearing and meat production.

The merits of entomophagy in the post COVID-19 world

BACKGROUND

In 2020, human society underwent several drastic changes due to the coronavirus disease 2019 (COVID-19) pandemic, which generated an unprecedented global impact. Since the onset of the COVID-19 pandemic, various pressing concerns underlying food security, such as transport, production, and maintenance of the supply chain, have been raised.

SCOPE AND APPROACH

The present study aimed to describe and review the merits of entomophagy in the post COVID-19 world, especially with regard to the low risk for zoonotic disease spread, high production rate, and future prospects for inducing entomophagy to enhance the diversity in the food system in comparison to conventional livestock.

KEY FINDINGS AND CONCLUSIONS

The advantages of entomophagy in the post COVID-19 world have been elucidated herein, with particular emphasis on the minimal risk of zoonotic disease transmission and production efficiency, in addition to the future goal of establishment of entomophagy to expand redundancy and diversity in the food system as against the utility of conventional livestock. In the current scenario, as well as in the post COVID-19 situation, boosting entomophagy may play a pivotal role in global food security, as the aspects already touched upon have amply demonstrated.

A Vavraia-like microsporidium as the cause of deadly infection in threatened and endangered Eurycea salamanders in the United States

Background

Eurycea sosorum (Barton Springs salamander) and Eurycea nana (San Macros salamander) are listed as endangered and threatened species, respectively, by the U.S. Fish and Wildlife Service (USFWS) with habitats restricted to small regions near Austin, Texas, USA. The conservation efforts with the Eurycea salamanders at the captive breeding program in San Marcos Aquatic Resources Center (SMARC), a USFWS facility, have seen an unexpected and increased mortality rate over the past few years. The clinical signs of sick or dead salamanders included erythema, tail loss, asymmetric gills or brachial loss, rhabdomyolysis, kyphosis, and behavior changes, suggesting that an infectious disease might be the culprit. This study aimed to identify the cause of the infection, determine the taxonomic position of the pathogen, and investigate the potential reservoirs of the pathogen in the environment.

Results

Histopathological examination indicated microsporidian infection (microsporidiosis) in the sick and dead Eurycea salamanders that was later confirmed by PCR detection. We also determined the near full-length small subunit ribosomal RNA (SSU rRNA) gene from the microsporidian pathogen, which allowed us to determine its phylogenetic position, and to design primers for specific and sensitive detection of the pathogen. Phylogenetic analysis indicated that this pathogen was closely related to the insect parasites Vavraia spp. and the human opportunistic pathogen, Trachipleistophora hominis. This Vavraia-like microsporidium was present in dead salamanders at SMARC archived between 2011 and 2015 (positive rates ranging between 52.0–88.9% by PCR detection), as well as in some aquatic invertebrates at the facility (e.g. snails and small crustaceans).

Conclusions

A Vavraia-like microsporidian was at least one of the major pathogens, if not solely, responsible for the sickness and mortality in the SMARC salamanders, and the pathogen had been present in the center for years. Environmental invertebrates likely served as a source and reservoir of the microsporidian pathogen. These observations provide new knowledge and a foundation for future conservation efforts for Eurycea salamanders including molecular surveys, monitoring of the pathogen, and discovery of effective treatments.

Electronic supplementary material

The online version of this article (10.1186/s13071-019-3369-z) contains supplementary material, which is available to authorized users.

The invasive cell coat at the microsporidian Trachipleistophora hominis-host cell interface contains secreted hexokinases

Microsporidia are obligate intracellular parasites causing significant disease in humans and economically important animals. In parallel to their extreme genetic reduction, Microsporidia have evolved novel mechanisms for exploiting host metabolism. A number of microsporidians confer secretion of otherwise cytosolic proteins by coding for signal peptides that direct entry into the endoplasmic reticulum. The human pathogen Trachipleistophora hominis encodes for four hexokinases, three of which have signal peptides at the N‐terminus. Here, we localized hexokinase 2 and hexokinase 3 through developmental stages of T. hominis using light and electron microscopy. Both proteins were concentrated in an extracellular coat previously termed the plaque matrix (PQM). The PQM (containing hexokinases) was morphologically dynamic, infiltrating the host cytoplasm predominantly during replicative stages. Throughout development the PQM interacted closely with endoplasmic reticulum that was demonstrated to be active in membrane protein biosynthesis and export. The impact of hexokinase on the host metabolism was probed using the fluorescent analog of glucose, 2‐NBDG, which displayed spatially restricted increases in signal intensity at the parasite/vacuole surface, coincident with hexokinase/PQM distribution. Gross metabolic aberrations, measured using metabolic profiling with the Seahorse XF Analyzer, were not detectable in mixed stage cocultures. Overall, these results highlight a role for the extended cell coat of T. hominis in host–parasite interactions, within which secreted hexokinases may work as part of a metabolic machine to increase glycolytic capacity or ATP generation close to the parasite surface.

Contrasting host-pathogen interactions and genome evolution in two generalist and specialist microsporidian pathogens of mosquitoes

Obligate intracellular pathogens depend on their host for growth yet must also evade detection by host defenses. Here we investigate host adaptation in two Microsporidia, the specialist Edhazardia aedis and the generalist Vavraia culicis, pathogens of disease vector mosquitoes. Genomic analysis and deep RNA-Seq across infection time courses reveal fundamental differences between these pathogens. E. aedis retains enhanced cell surface modification and signalling capacity, upregulating protein trafficking and secretion dynamically during infection. V. culicis is less dependent on its host for basic metabolites and retains a subset of spliceosomal components, with a transcriptome broadly focused on growth and replication. Transcriptional profiling of mosquito immune responses reveals that response to infection by E. aedis differs dramatically depending on the mode of infection, and that antimicrobial defensins may play a general role in mosquito defense against Microsporidia. This analysis illuminates fundamentally different evolutionary paths and host interplay of specialist and generalist pathogens.