genome-editing-yellow-fever-mosquito-aedes-aegypti-using-crispr

Genome Editing in the Yellow Fever Mosquito <em>Aedes aegypti</em> using CRISPR-Cas9

The emergence of the clustered, regularly interspersed, short palindromic repeats (CRISPR)-Cas9 technology has revolutionized the genetic engineering ...

University of California, San Diego

African populations of the mosquito  are usually considered less susceptible to infection by human-pathogenic flaviviruses than globally invasive populations found outside Africa. Although this contrast has been well documented for Zika virus (ZIKV), it is unclear to what extent it is true for dengue virus (DENV), the most prevalent flavivirus of humans. Addressing this question is complicated by substantial genetic diversity among DENV strains, most notably in the form of four genetic types (DENV1 to DENV4), that can lead to genetically specific interactions with mosquito populations. Here, we carried out a continent-wide survey of DENV susceptibility using a panel of field-derived  colonies from across the African range of the species and a colony from Guadeloupe, French West Indies as non-African reference. We found considerable variation in the ability of African  populations to acquire and replicate a panel of six DENV strains spanning the four DENV types. Although African  populations were generally less susceptible than the reference non-African population from Guadeloupe, in several instances some African populations were equally or more susceptible than the Guadeloupe population. Moreover, the relative level of susceptibility between African mosquito populations depended on the DENV strain, indicating genetically specific interactions. We conclude that unlike ZIKV susceptibility, there is no clear-cut dichotomy in DENV susceptibility between African and non-African . DENV susceptibility of African  populations is highly heterogeneous and largely governed by the specific pairing of mosquito population and DENV strain.

Extensive variation and strain-specificity in dengue virus susceptibility among African  populations.

Climate change is expected to profoundly affect mosquito distributions and their ability to serve as vectors for disease, specifically with the anticipated increase in heat waves. The rising temperature and frequent heat waves can accelerate mosquito life cycles, facilitating higher disease transmission. Conversely, higher temperatures could increase mosquito mortality as a negative consequence. Warmer temperatures are associated with increased human density, suggesting a need for anthropophilic mosquitoes to adapt to be more hardy to heat stress. Mosquito eggs provide an opportunity to study the biological impact of climate warming as this stage is stationary and must tolerate temperatures at the site of female oviposition. As such, egg thermotolerance is critical for survival in a specific habitat. In nature,  mosquitoes exhibit different behavioral phenotypes, where specific populations prefer depositing eggs in tree holes and prefer feeding non-human vertebrates. In contrast, others, particularly human-biting specialists, favor laying eggs in artificial containers near human dwellings. This study examined the thermotolerance of eggs, along with adult stages, for  and  lineages associated with known ancestry and shifts in their relationship with humans. Mosquitoes collected from areas with higher human population density, displaying increased human preference, and having a human-associated ancestry profile have increased egg viability following high-temperature stress. Unlike eggs, thermal tolerance among adults showed no significant correlation based on the area of collection or human-associated ancestry. This study highlights that the egg stage is likely critical to mosquito survival when associated with humans and needs to be accounted when predicting future mosquito distribution.

Thermal tolerance of mosquito eggs is associated with urban adaptation and human interactions.

Aedes aegypti is an important mosquito vector of human disease with a wide distribution across the globe. Climatic conditions and ecological pressure drive differences in the biology of several populations of this mosquito species, including blood-feeding behaviour and vector competence. However, no study has compared activity and/or sleep among different populations/lineages of Ae. aegypti. Having recently established sleep-like states in three mosquito species with observable differences in timing and amount of sleep among species, we investigated differences in activity and sleep levels among 17 Ae. aegypti lines drawn from both its native range in Africa and its invasive range across the global tropics. Activity monitoring indicates that all the lines show consistent diurnal activity, but significant differences in activity level, sleep amount, number of sleep bouts and bout duration were observed among the lines. The variation in day activity was associated with differences in host preference and ancestry for the lineages collected in Africa. This study provides evidence that the diurnal sleep and activity profiles for Ae. aegypti are consistent, but there are significant population differences for Ae. aegypti sleep and activity levels and interactions with host species may significantly impact mosquito activity.

Intra-species quantification reveals differences in activity and sleep levels in the yellow fever mosquito, Aedes aegypti.

Zika virus (ZIKV) outbreaks have raised major global health concerns recently, yet reported outbreaks are rare in Africa, where ZIKV was first discovered. Recent studies on Aedes aegypti, the mosquito that transmits ZIKV, might explain this phenomenon. The Ae aegypti subspecies present in Africa shows lower preference for biting humans and reduced susceptibility to ZIKV infection compared with the subspecies distributed outside Africa. Alternatively, climate might strongly limit transmission as it affects multiple traits of ZIKV and the mosquito vector.

Article	Year
Extensive variation and strain-specificity in dengue virus susceptibility among African populations. bioRxiv : the preprint server for biology\| PubMed ID: 38168387	2023
Thermal tolerance of mosquito eggs is associated with urban adaptation and human interactions. bioRxiv : the preprint server for biology\| PubMed ID: 38585904	2024
Intra-species quantification reveals differences in activity and sleep levels in the yellow fever mosquito, Aedes aegypti. Medical and veterinary entomology\| PubMed ID: 39300685	2024
The role of vector population variation and climate in Zika virus transmission patterns in Africa: a modelling study. The Lancet. Planetary health\| PubMed ID: 39674192	2024

Noah H. Rose

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