Tripartite interactions between viruses, parasites, and mosquitoes.

Mosquito-borne diseases have a major impact on global human health. Biological agents that colonize the mosquito vector are increasingly explored as an intervention strategy to prevent vector-borne disease transmission. For instance, the release of mosquitoes carrying the endosymbiotic bacterium Wolbachia effectively reduced dengue virus incidence and disease. Insect-specific viruses are likewise considered as biocontrol agents against vector-borne diseases. While most studies focused on insect-specific viruses as an intervention against arthropod-borne viruses, we here consider whether mosquito-specific viruses may affect the transmission of the malaria-causing Plasmodium parasite by Anopheles mosquitoes. Although there is no direct experimental evidence addressing this question, we found that viral infections in dipteran insects activate some of the immune pathways that are antiparasitic in Anopheles. These findings suggest that indirect virus-parasite interactions could occur and that insect-specific viruses may modulate malaria transmission. Tripartite interactions between viruses, parasites, and Anopheles mosquitoes thus merit further investigation.

Composition and global distribution of the mosquito virome - A comprehensive database of insect-specific viruses.

Mosquitoes are vectors for emerging and re-emerging infectious viral diseases of humans, livestock and other animals. In addition to these arthropod-borne (arbo)viruses, mosquitoes are host to an array of insect-specific viruses, collectively referred to as the mosquito virome. Mapping the mosquito virome and understanding if and how its composition modulates arbovirus transmission is critical to understand arboviral disease emergence and outbreak dynamics. In recent years, next-generation sequencing as well as PCR and culture-based methods have been extensively used to identify mosquito-associated viruses, providing insights into virus ecology and evolution. Until now, the large amount of mosquito virome data, specifically those acquired by metagenomic sequencing, has not been comprehensively integrated. We have constructed a searchable database of insect-specific viruses associated with vector mosquitoes from 175 studies, published between October 2000 and February 2022. We identify the most frequently detected and widespread viruses of the Culex, Aedes and Anopheles mosquito genera and report their global distribution. In addition, we highlight the challenges of extracting and integrating published virome data and we propose that a standardized reporting format will facilitate data interpretation and re-use by other scientists. We expect our comprehensive database, summarizing mosquito virome data collected over 20 years, to be a useful resource for future studies.

Comparative analysis of glass and Hemotek membrane feeding systems for malaria transmission research.

BACKGROUND: Glass membrane feeders are used in malaria research for artificial blood feeding. This study investigates the use of Hemotek membrane feeders as a standardized alternative feeding system. METHODS: Hemotek feeders were compared with glass feeders by assessing mosquito feeding rate, imbibed blood meal volume and Plasmodium falciparum infection intensity on mosquito guts. RESULTS: While mosquito feeding rate and blood meal volume were comparable between Hemotek and glass feeders, a loss in transmission was observed using the Hemotek feeder with a conventional collagen membrane. There was no difference in transmission between both feeders when Parafilm was used as the membrane. CONCLUSIONS: Hemotek feeders with a Parafilm membrane can be used as an alternative feeding system for malaria transmission research.

The spread of the first introns in proto-eukaryotic paralogs.

Spliceosomal introns are a unique feature of eukaryotic genes. Previous studies have established that many introns were present in the protein-coding genes of the last eukaryotic common ancestor (LECA). Intron positions shared between genes that duplicated before LECA could in principle provide insight into the emergence of the first introns. In this study we use ancestral intron position reconstructions in two large sets of duplicated families to systematically identify these ancient paralogous intron positions. We found that 20-35% of introns inferred to have been present in LECA were shared between paralogs. These shared introns, which likely preceded ancient duplications, were wide spread across different functions, with the notable exception of nuclear transport. Since we observed a clear signal of pervasive intron loss prior to LECA, it is likely that substantially more introns were shared at the time of duplication than we can detect in LECA. The large extent of shared introns indicates an early origin of introns during eukaryogenesis and suggests an early origin of a nuclear structure, before most of the other complex eukaryotic features were established.

Bacterial membrane vesicles as promising vaccine candidates.

Both Gram-positive and Gram-negative bacteria can release nano-sized lipid bilayered structures, known as membrane vesicles (MVs). These MVs play an important role in bacterial survival by orchestrating interactions between bacteria and between bacteria and host. The major constituents of MVs are proteins, lipids and nucleic acids. Due to the immunogenicity of the membrane lipids and/or proteins of the MVs, in combination with adjuvant danger signals and the repeating patterns on the nanosized surface, MVs can effectively stimulate the innate and adaptive immune system. Since they are non-replicating, they are safer than attenuated vaccines. In addition, by genetic engineering of the donor cells, further improvements to their safety profile, immunogenicity and yield can be achieved. To date, one MV-based vaccine against Neisseria meningitidis (N. meningitidis) serogroup B was approved. Other (engineered) MVs in the pipeline study are mostly in the preclinical phase.