Biology subjects

Moreira, L. A.

Publications and source records attributed to Moreira, L. A..

7 recordsLinked to original sources

bioRxiv2025

Comparison of oviposition and adult trapping to monitor wMel introgression for Wolbachia-based vector control

Wolbachia introgression into Aedes aegypti mosquito populations has been shown to be effective in preventing dengue and is being evaluated for WHO prequalification. Monitoring the long-term introgression of Wolbachia (wMel)-positive Aedes aegypti mosquitoes, however, requires labor-intensive and costly BG-Sentinel traps (BG-traps). More affordable alternatives, such as using oviposition traps (ovitraps), have not been fully evaluated. Ae. aegypti eggs and adults were collected from 124 ovitraps and 237 BG-traps, respectively, across 12 clusters in Belo Horizonte, Brazil from March to May 2023 as part of the EVITA Dengue trial. We used a qPCR assay to detect wMel in a sample of L3-L4 stage larvae (up to 29) that were reared from eggs in ovitraps and adults from BG-traps (up to 10 per BG-trap). We used mixed effects models to compare estimates of cluster-level wMel introgression from ovitrap and BG-trap data over time. Among 3,675 larvae reared from ovitraps, wMel prevalence was 0.50 (95% CI: 0.48-0.51). Among 1,244 adult Ae. aegypti tested from BG-traps, wMel prevalence was 0.45 (95% CI: 0.42-0.48). Cluster-level wMel introgression in larvae and adults was highly correlated (Spearmans r = 0.70, p = 6.71e-06). Multivariate analysis found that ovitrap estimates of introgression were associated with BG-trap estimates in the same month when models incorporated the previous months ovitrap wMel-positive count, the proportion of wMel in ovitraps in the current and previous month, and Ae. aegypti abundance. Leveraging this model, predicted wMel introgression from ovitrap data were highly correlated with observed introgression from BG-trap data (rs,counts=0.98, p=1.53e-14; rs,prevalences=0.82, p=0.11e-05) and provided greater precision than crude ovitrap-based estimates. These findings indicate that ovitrap-based monitoring represents a low cost, more efficient approach to evaluating introgression as the Wolbachia-based interventions are scaled up and implemented broadly in high burden regions for dengue and other arboviral diseases. Author SummaryDengue fever is a major global health burden, and one promising way to control it is by releasing Aedes aegypti mosquitoes infected with a bacteria called Wolbachia. This bacteria reduces the mosquitoes ability to spread dengue. However, monitoring the success of Wolbachia in mosquito populations over time requires expensive and labor-intensive traps. Our study explored a more affordable alternative: using oviposition traps (ovitraps), which collect mosquito eggs instead of adults. In Belo Horizonte, Brazil, we compared data from eggs collected in ovitraps with data from standard mosquito traps (BG-traps) that catch adult mosquitoes. By analyzing the mosquitoes for Wolbachia, we found that the egg-based method provided reliable estimates of Wolbachia levels in the mosquito population. These results suggest that ovitraps could be a cost-effective and efficient way to monitor Wolbachias spread. This approach could help improve dengue prevention efforts, making it easier for public health programs to track and expand this control strategy in areas where dengue is a major concern.

ecology↗

bioRxiv2024

Wolbachia introgression in Ae. aegypti is accompanied by variable loss - a multi-country assessment

The wMel and wAlbB strains of the bacterial endosymbiont Wolbachia are being introgressed into Aedes aegypti populations as a biocontrol method to reduce the transmission of medically important arboviruses. Successful introgression of Wolbachia relies on both persistence of Wolbachia throughout the host life cycle and a high fidelity of maternal transmission of Wolbachia between generations. wMel has been introgressed into field populations in 14 countries to date. Monitoring of field sites has shown that wMel prevalence can fluctuate substantially over time, prompting concerns this could lead to reduced efficacy of the biocontrol method. To explore the fidelity of wMel persistence and transmission, we developed molecular methods to measure the prevalence of Ae. aegypti negative for Wolbachia infection but carrying the "founder" mitochondrial haplotype of the single female first transinfected. As all released wMel-infected mosquitoes and any subsequent offspring will carry this founder mitochondrial haplotype, any mosquitoes with this mitochondrial haplotype and without wMel indicate that wMel was lost from this lineage at some point. We observed loss of wMel ranging from 0 to 20.4% measured at various time intervals after wMel-infected mosquito releases in five different countries. Despite some field sites showing Wolbachia loss, overall Wolbachia prevalence was sustained during the time periods studied. We then employed laboratory studies to explore factors that could contribute to the loss of wMel. Surprisingly, near-perfect maternal transmission was measured across laboratory conditions of early blood feeding, starvation, and salinity. Collectively, these findings underscore that although wMel transmission can be imperfect it does not necessarily undermine population-level establishment, providing encouragement that the intervention will be robust in most dengue-endemic environments.

ecology↗

bioRxiv2022

Breeding site microbiota and oviposition: do female Aedes aegypti shape bacterial communities?

Aedes aegypti, the main vector of multiple arboviruses, is highly associated with human dwellings. Females exhibit an opportunistic oviposition behavior, seldomly laying eggs on natural containers, but rather distributing them among human-generated breeding sites. Bacterial communities associated with such sites, as well as the compositional shifts they undergo through the development of larval stages, have been described. Some bacteria can play a direct role in supporting the success of mosquito development. Additionally, exposure to different bacteria during larval phases can have an impact on life-history traits. Whether the larvae acquire symbionts from aquatic niches, or just require bacteria as food, is still debated. Based on these facts, we hypothesized that female Ae. aegypti shape the bacterial communities of breeding sites during oviposition as a form of niche construction to favor offspring fitness. Our study presents a series of experiments to address whether gravid females modify bacterial consortia present in larval habitats. For this, we first verified if females can mechanically transfer bacteria into culture media. As evidence of mechanical transmission was obtained, we then elaborated an experimental scheme to dissect effects from factors related to the act of oviposition and mosquito-egg-water interactions. The DNA samples obtained from breeding site water belonging to five treatments were subjected to amplicon-oriented sequencing to infer their bacterial community structure. Microbial ecology analyses revealed significant differences between treatments in terms of diversity. Particularly, between-treatment shifts in abundance profiles were detected, also showing that females induce a significant decrease in alpha diversity through oviposition. In addition, indicator species analysis pinpointed bacterial taxa with significant predicting values and fidelity coefficients for the samples in which single females laid eggs. Furthermore, we provide evidence regarding how one of these indicator taxa, Elizabethkingia, exerts a positive effect upon the development and fitness of mosquito larvae, thus suggesting that the developmental niche construction hypothesis may hold in this model.

ecology↗

bioRxiv2021

Large-scale deployment and establishment of Wolbachia into the Aedes aegypti population in Rio de Janeiro, Brazil.

Traditional methods of vector control have proven insufficient to reduce the alarming incidence of Dengue, Zika and chikungunya in endemic countries. The bacterium symbiont Wolbachia has emerged as an efficient pathogen-blocking and self-dispersing agent that reduces the vectorial potential of Aedes aegypti populations and potentially impairs arboviral disease transmission. In this work, we report the results of a large-scale Wolbachia intervention in Ilha do Governador, Rio de Janeiro, Brazil. wMel-infected adults were released across residential areas between August 2017 and March 2020. Over 131 weeks, including release and post-release phases, we monitored the wMel prevalence in field specimens, and analyzed introgression profiles of two assigned intervention areas, RJ1 and RJ2. Our results revealed that wMel successfully invaded both areas, reaching overall infection rates of 50-70% in RJ1, and 30-60% in RJ2 by the end of the monitoring period. At the neighborhood-level, wMel introgression was heterogeneous in both RJ1 and RJ2, with some profiles sustaining a consistent increase in infection rates and others failing to elicit the same. Correlation analysis revealed a weak overall association between RJ1 and RJ2 (r = 0.2849, P = 0.0236), and an association at a higher degree when comparing different deployment strategies, vehicle or backpack-assisted, within RJ1 (r = 0.4676, P < 0.0001) or RJ2 (r = 0.6263, P < 0.0001). The frequency knockdown resistance (kdr) alleles in wMel-infected specimens from both areas was consistently high over this study. Altogether, these findings corroborate that wMel can be successfully deployed at large-scale as part of vector control intervention strategies, and provide the basis for imminent disease impact studies in Southeastern Brazil.

ecology↗

bioRxiv2020

Simplified artificial blood feeding and oral infection method for mosquitoes

Mosquitoes such as Aedes aegypti, Aedes albopictus and Culex quinquefasciatus are vectors of many pathogens that greatly affect humankind. The maintenance of these mosquitoes in laboratory permit different studies that can help understanding their biology, as well as the vector-pathogen interaction. In addition to sugar meals, the blood feeding is essential for maintenance of the reproductive cycle in several vectors. The main blood sources for many mosquito colonies are direct feeding on live animal or the use of human/animal blood through artificial feeders. However, this latter process has some disadvantages, as artificial feeders can be very laborious for assembly and decontamination. Based on these observations, a simplified technique for feeding and artificial infection was developed with cotton-pads soaked (CS) and blood or blood and viral supernatant to simulate an artificial infection. The efficiency of the CS technique was investigated through the number of mosquitoes fed/infected, when compared to their respective control group. The CS technique, with blood at room temperature, promoted a feeding rate of 61.4% for Ae. albopictus, 70.8% for Cx. quinquefasciatus and 17% for Ae. aegypti. The control group (Hemotec-feeding) presented 47.9%, 16.5% and 59.1% of feeding success, respectively. To improve the CS technique for Ae. aegypti mosquitoes, the procedure was then performed with blood at 38{degrees}C, which was possible to observe a feeding rate of 47.3%, in comparison to 53.2% for the control group (Hemotec). When using the CS technique for artificial infection with Mayaro virus, more than 80% of infection was observed for Ae. aegypti and 100% for Ae. albopictus. In the traditional infection technique (glass feeder), the infection rate was 90% (Ae. aegypti) and 96.6% (Ae. albopictus). For Cx. quinquefasciatus, the infection was positive only with the CS technique, resulting in 1 (5%) mosquito infected with Mayaro virus. Our results suggest that this simplified technique of low-cost feeding and easy assembly, offers good results for feeding (maintenance of colonies) and artificial infection of different species of mosquitoes.

developmental biology↗

bioRxiv2020

Reduced competence to arboviruses following the sustainable invasion of Wolbachia into native Aedes aegypti from Niteroi, Southeastern Brazil

Field release of Wolbachia-infected Aedes aegypti has emerged as a promising solution to manage the transmission of dengue, Zika and chikungunya in endemic areas across the globe. Through an efficient self-dispersing mechanism, and the ability to induce virus-blocking properties, Wolbachia offers an unmatched potential to gradually modify wild Ae. aegypti populations turning them unsuitable disease vectors. Here in this work, a proof-of-concept field trial was carried out in a small community of Niteroi, greater Rio de Janeiro. Following the release of Wolbachia-infected eggs, we reported a successful invasion and long-term establishment of the bacterium across the territory, as denoted by stable high-infection indexes (>80%). We have also demonstrated that refractoriness to dengue and Zika viruses, either thorough oral-feeding or intra-thoracic saliva challenging assays, were maintained over the adaptation to the natural environment of Southeastern Brazil. These findings further support Wolbachias ability to invade local Ae. aegypti populations and impair disease transmission, and shall pave the way for future epidemiological and economic impact assessments.

microbiology↗

bioRxiv2019

Vector competence of Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus mosquitoes for Mayaro virus

Newly emerging or re-emerging arthropod-borne viruses (arboviruses) are important causes of human morbidity and mortality nearly worldwide. Arboviruses such as Dengue (DENV), Zika (ZIKV), Chikungunya (CHIKV) and West Nile virus (WNV) underwent an extensive geographic expansion in the tropical and sub-tropical regions of the world. In the Americas the main vectors, for DENV, ZIKV and CHIKV, are mosquito species adapted to urban environments namely Aedes aegypti and Aedes albopictus, whereas the main vector for WNV is the Culex quinquefasciatus. Given the widespread distribution in the Americas and high permissiveness to arbovirus infection, theses mosquito species might pose an important role in the epidemiology of other arboviruses normally associated to sylvatic vectors. Here, we test this hypothesis by determining the vector competence of Ae. aegypti, Ae. albopictus and Cx. quinquefasciatus to Mayaro (MAYV) virus, a sylvatic arbovirus transmitted mainly by Haemagogus janthinomys that have been causing an increasing number of outbreaks in South America namely in Brazil. Using field mosquitoes from Brazil, female mosquitoes were experimentally infected and their competence for dissemination and transmission for MAYV was evaluated. We found high dissemination rate for MAYV in Ae. aegypti (57.5%) and Ae. albopictus (61.6%), whereas very low rates were obtained for Cx. quinquefasciatus (2.5%). Concordantly, we observed that Ae. aegypti and Ae. albopictus have high transmission ability (69.5% and 71.1% respectively), conversely to Cx. quinquefasciatus that is not able to transmit the MAYV. Notably, we found that very low quantities of virus present in the saliva (undetectable by RT-qPCR) were sufficient and virulent enough to guarantee transmission. Although Ae. aegypti and Ae. albopictus mosquitoes are not the main vectors for MAYV, our studies suggest that these vectors may play a significant role in the transmission of this arbovirus, since both species showed high vector competence in laboratory conditions.\n\nAuthor summaryThe present study showed that Ae. aegypti and Ae. albopictus mosquitoes have high vector competence for MAYV, in laboratory. In contrast, Cx. quinquefasciatus mosquitoes were shown to be refractory to MAYV. Regarding the viral dilution and nanoinjection, higher detection sensitivity was observed after virus nanoinjection into naive mosquitoes, indicating that only a few viral particles are required to infect mosquitoes, and these particles may not be detected by RT-qPCR before the nanoinjection procedure.

microbiology↗