First Detection and Genetic Identification of Wolbachia Endosymbiont in Field-Caught Aedes aegypti (Diptera: Culicidae) Mosquitoes Collected from Southern Taiwan

Adaptative Divergence of Cryptococcus neoformans: Phenetic and Metabolomic Profiles Reveal Distinct Pathways of Virulence and Resistance in Clinical vs. Environmental Isolates

Cryptococcus neoformans is a life-threatening fungal pathogen that primarily affects immunocompromised individuals. While antiretroviral therapy has reduced incidence in developed nations, fluconazole-resistant strains and virulent environmental isolates continue to pose challenges, especially because they have many mechanisms of adaptability, supporting their survival. This study explores the phenetic and metabolomic adaptations of C. neoformans in clinical and environmental contexts to understand the factors influencing pathogenicity and resistance.

METHODS

An in silico observational study was conducted with 16 C. neoformans isolates (6 clinical, 9 environmental, and 1 reference) from the NCBI database. Molecular phenetic analysis used MEGA version 11.0.13 and focused on efflux pump protein sequences. Molecular phenetic relationships were assessed via the UPGMA clustering method with 1000 bootstrap replicates. The enzymatic profiling of glycolytic pathways was conducted with dbCAN, and metabolomic pathway enrichment analysis was performed in MetaboAnalyst 6.0 using the KEGG pathway database.

RESULTS

Molecular phenetic analysis revealed distinct clustering patterns among isolates, reflecting adaptations associated with clinical and environmental niches. Clinical isolates demonstrated enriched sulfur metabolism and glutathione pathways, likely adaptations to oxidative stress in host environments, while environmental isolates favored methane and glyoxylate pathways, suggesting adaptations for survival in carbon-rich environments.

CONCLUSION

Significant phenetic and metabolomic distinctions between isolates reveal adaptive strategies for enhancing virulence and antifungal resistance, highlighting potential therapeutic targets.

Population genetic structure of Culex tritaeniorhynchus in different types of climatic zones in China

BACKGROUND

Culex tritaeniorhynchus is widely distributed in China, from Hainan Island in the south to Heilongjiang in the north, covering tropical, subtropical, and temperate climate zones. Culex tritaeniorhynchus carries 19 types of arboviruses. It is the main vector of the Japanese encephalitis virus (JEV), posing a serious threat to human health. Understanding the effects of environmental factors on Culex tritaeniorhynchus can provide important insights into its population structure or isolation patterns, which is currently unclear.

RESULTS

In total, 138 COI haplotypes were detected in the 552 amplified sequences, and the haplotype diversity (Hd) value increased from temperate (0.534) to tropical (0.979) regions. The haplotype phylogeny analysis revealed that the haplotypes were divided into two high-support evolutionary branches. Temperate populations were predominantly distributed in evolutionary branch II, showing some genetic isolation from tropical/subtropical populations and less gene flow between groups. The neutral test results of HNQH (Qionghai) and HNHK(Haikou) populations were negative (P < 0.05), indicating many low-frequency mutations in the populations and that the populations might be in the process of expansion. Moreover, Wolbachia infection was detected only in SDJN (Jining) (2.24%), and all Wolbachia genotypes belonged to supergroup B. To understand the influence of environmental factors on mosquito-borne viruses, we examined the prevalence of Culex tritaeniorhynchus infection in three ecological environments in Shandong Province. We discovered that the incidence of JEV infection was notably greater in Culex tritaeniorhynchus from lotus ponds compared to those from irrigation canal regions. In this study, the overall JEV infection rate was 15.27 per 1000, suggesting the current risk of Japanese encephalitis outbreaks in Shandong Province.

CONCLUSIONS

Tropical and subtropical populations of Culex tritaeniorhynchus showed higher genetic diversity and those climatic conditions provide great advantages for the establishment and expansion of Culex tritaeniorhynchus. There are differences in JEV infection rates in wild populations of Culex tritaeniorhynchus under different ecological conditions. Our results suggest a complex interplay of genetic differentiation, population structure, and environmental factors in shaping the dynamics of Culex tritaeniorhynchus. The low prevalence of Wolbachia in wild populations may reflect the recent presence of Wolbachia invasion in Culex tritaeniorhynchus.

Revisiting Wolbachia detections: Old and new issues in Aedes aegypti mosquitoes and other insects

Wolbachia continue to be reported in species previously thought to lack them, particularly Aedes aegypti mosquitoes. The presence of Wolbachia in this arbovirus vector is considered important because releases of mosquitoes with transinfected Wolbachia are being used around the world to suppress pathogen transmission and these efforts depend on a lack of Wolbachia in natural populations of this species. We previously assessed papers reporting Wolbachia in natural populations of Ae. aegypti and found little evidence that seemed convincing. However, since our review, more and more papers are emerging on Wolbachia detections in this species. Our purpose here is to evaluate these papers within the context of criteria we previously established but also new criteria that include the absence of releases of transinfections within the local areas being sampled which has contaminated natural populations in at least one case where novel detections have been reported. We also address the broader issue of Wolbachia detection in other insects where similar issues may arise which can affect overall estimates of this endosymbiont more generally. We note continuing shortcomings in papers purporting to find natural Wolbachia in Ae. aegypti which are applicable to other insects as well.

Detection and quantification of natural Wolbachia in Aedes aegypti in Metropolitan Manila, Philippines using locally designed primers

Background

The Philippines bears health and economic burden caused by high dengue cases annually. Presently, the Philippines still lack an effective and sustainable vector management. The use of Wolbachia, a maternally transmitted bacterium, that mitigate arbovirus transmission has been recommended. Cytoplasmic incompatibility and viral blocking, two characteristics that make Wolbachia suitable for vector control, depend on infection prevalence and density. There are no current Wolbachia release programs in the Philippines, and studies regarding the safety of this intervention. Here, we screened for Wolbachia in Aedes aegypti collected from Metropolitan Manila, Philippines. We designed location-specific primers for qPCR to test whether this improved Wolbachia detection in Ae. aegypti. We explored if host sex and Wolbachia strain could be potential factors affecting Wolbachia density.

Methods

Ae. aegypti mosquitoes (n=429) were screened for natural Wolbachia by taqman qPCR using location-specific Wolbachia surface protein primers (wspAAML) and known 16S rRNA primers. Samples positive for wspAAML (n=267) were processed for Sanger sequencing. We constructed a phylogenetic tree using IQ-TREE 2 to further characterize Wolbachia present in the Philippine Ae. aegypti. We then compared Wolbachia densities between Wolbachia groups and host sex. Statistical analyses were done using GraphPad Prism 9.0.

Results

Wolbachia prevalence for 16S rRNA (40%) and wspAAML (62%) markers were high. Wolbachia relative densities for 16S rRNA ranged from -3.84 to 2.71 and wspAAML from -4.02 to 1.81. Densities were higher in male than female mosquitoes. Wolbachia strains detected in Ae. aegypti clustered into supergroup B. Some 54% (123/226) of these sequences clustered under a group referred to here as "wAegML," that belongs to the supergroup B, which had a significantly lower density than wAegB/wAlbB, and wAlbA strains.

Conclusion

Location-specific primers improved detection of natural Wolbachia in Ae. aegypti and allowed for relative quantification. Wolbachia density is relatively low, and differed between host sexes and Wolbachia strains. An economical way of confirming sporadic or transient Wolbachia in Ae. aegypti is necessary while considering host sex and bacterial strain.

A tangled threesome: understanding arbovirus infection in Aedes spp. and the effect of the mosquito microbiota

Arboviral infections transmitted by Aedes spp. mosquitoes are a major threat to human health, particularly in tropical regions but are expanding to temperate regions. The ability of Aedes aegypti and Aedes albopictus to transmit multiple arboviruses involves a complex relationship between mosquitoes and the virus, with recent discoveries shedding light on it. Furthermore, this relationship is not solely between mosquitoes and arboviruses, but also involves the mosquito microbiome. Here, we aimed to construct a comprehensive review of the latest information about the arbovirus infection process in A. aegypti and A. albopictus, the source of mosquito microbiota, and its interaction with the arbovirus infection process, in terms of its implications for vectorial competence. First, we summarized studies showing a new mechanism for arbovirus infection at the cellular level, recently described innate immunological pathways, and the mechanism of adaptive response in mosquitoes. Second, we addressed the general sources of the Aedes mosquito microbiota (bacteria, fungi, and viruses) during their life cycle, and the geographical reports of the most common microbiota in adults mosquitoes. How the microbiota interacts directly or indirectly with arbovirus transmission, thereby modifying vectorial competence. We highlight the complexity of this tripartite relationship, influenced by intrinsic and extrinsic conditions at different geographical scales, with many gaps to fill and promising directions for developing strategies to control arbovirus transmission and to gain a better understanding of vectorial competence. The interactions between mosquitoes, arboviruses and their associated microbiota are yet to be investigated in depth.