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Aedes spp. comprise the primary group of mosquitoes that transmit arboviruses such as dengue, Zika, and chikungunya viruses to humans, and thus these insects pose a significant burden on public health worldwide. Advancements in next-generation sequencing and metagenomics have expanded our knowledge on the richness of RNA viruses harbored by arthropods such as Ae. aegypti and Ae. albopictus. Increasing evidence suggests that vector competence can be modified by the microbiome (comprising both bacteriome and virome) of mosquitoes present in endemic zones. Using an RNA-seq-based metataxonomic approach, this study determined the virome structure, Wolbachia presence and mitochondrial diversity of field-caught Ae. aegypti and Ae. albopictus mosquitoes in Medellín, Colombia, a municipality with a high incidence of mosquito-transmitted arboviruses. The two species are sympatric, but their core viromes differed considerably in richness, diversity, and abundance; although the community of viral species identified was large and complex, the viromes were dominated by few virus species. BLAST searches of assembled contigs suggested that at least 17 virus species (16 of which are insect-specific viruses [ISVs]) infect the Ae. aegypti population. Dengue virus 3 was detected in one sample and it was the only pathogenic virus detected. In Ae. albopictus, up to 11 ISVs and one plant virus were detected. Therefore, the virome composition appears to be species-specific. The bacterial endosymbiont Wolbachia was identified in all Ae. albopictus samples and in some Ae. aegypti samples collected after 2017. The presence of Wolbachia sp. in Ae. aegypti was not related to significant changes in the richness, diversity, or abundance of this mosquito's virome, although it was related to an increase in the abundance of Aedes aegypti To virus 2 (Metaviridae). The mitochondrial diversity of these mosquitoes suggested that the Ae. aegypti population underwent a change that started in the second half of 2017, which coincides with the release of Wolbachia-infected mosquitoes in Medellín, indicating that the population of wMel-infected mosquitoes released has introduced new alleles into the wild Ae. aegypti population of Medellín. However, additional studies are required on the dispersal speed and intergenerational stability of wMel in Medellín and nearby areas as well as on the introgression of genetic variants in the native mosquito population. [ABSTRACT FROM AUTHOR]

Due to the rapid spread of Zika virus (ZIKV) infection after its emergence in the Americas in 2015 and its relationship with birth defects, it became declared a Public Health Emergency of International Concern (WHO). The main mechanism by which this virus circulates in nature is horizontal transmission between vectors and humans. However, it has been suggested that vertical transmission (parent to offspring infection) or venereal mosquito-mosquito transmission may have an important role in viral populations maintenance during inter-epidemic periods. In this study we evaluate the presence of ZIKV in males and females of Aedes aegypti and Ae. albopictus in Medellín, Colombia, throughout the post-epidemic period of 2017 and 2018. A total of 7986 mosquitoes Aedes sp. resting within houses were captured and grouped in 2768 pools; 146 of these were RT-PCR positive for ZIKV, of which 38 (26%) were male mosquito pools (36 of Ae. aegypti and 2 of Ae. albopictus). The partial NS5 gene was sequenced in all ZIKV PCR-positive pools to confirm the ZIKV presence throughout spatial and temporal sampling. The results suggest a vector role of ZIKV by Ae. Albopictus ; and because it is well known that male mosquitoes are not hematophagous, the high rate detection of ZIKV in male Aedes mosquitoes pools supports the existence of vertical or venereal transmission in Medellín, which can contribute to ZIKV maintenance during low transmission periods. This study provides a better understanding of the population dynamics of ZIKV in an endemic region during an inter-epidemic period and supports alternative transmission pathways as a mechanism to maintain endemism of this arbovirus. • Presence of ZIKV in males and females of Aedes aegypti and Ae. albopictus in Medellín, between 2017 and 2018. • Ø ZIKV presence in Ae. albopictus suggests a role as a vector in Colombia. • High rate detection of ZIKV in male Aedes mosquitoes supports the existence of vertical or venereal transmission in Medellín. • Alternative transmission mechanisms facilitate the maintenance of ZIKV in periods of low mosquito-human transmission. [ABSTRACT FROM AUTHOR]