Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.233
Filtrar
1.
Nat Commun ; 12(1): 1810, 2021 03 22.
Artículo en Inglés | MEDLINE | ID: mdl-33753725

RESUMEN

For most pathogens, transmission is driven by interactions between the behaviours of infectious individuals, the behaviours of the wider population, the local environment, and immunity. Phylogeographic approaches are currently unable to disentangle the relative effects of these competing factors. We develop a spatiotemporally structured phylogenetic framework that addresses these limitations by considering individual transmission events, reconstructed across spatial scales. We apply it to geocoded dengue virus sequences from Thailand (N = 726 over 18 years). We find infected individuals spend 96% of their time in their home community compared to 76% for the susceptible population (mainly children) and 42% for adults. Dynamic pockets of local immunity make transmission more likely in places with high heterotypic immunity and less likely where high homotypic immunity exists. Age-dependent mixing of individuals and vector distributions are not important in determining spread. This approach provides previously unknown insights into one of the most complex disease systems known and will be applicable to other pathogens.


Asunto(s)
Algoritmos , Virus del Dengue/genética , Dengue/transmisión , Modelos Teóricos , Adulto , Aedes/virología , Animales , Niño , Dengue/epidemiología , Dengue/virología , Virus del Dengue/clasificación , Virus del Dengue/fisiología , Genoma Viral/genética , Interacciones Huésped-Patógeno , Humanos , Mosquitos Vectores/virología , Filogenia , Filogeografía/métodos , Filogeografía/estadística & datos numéricos , Dinámica Poblacional , Tailandia/epidemiología
2.
Nat Commun ; 12(1): 916, 2021 02 10.
Artículo en Inglés | MEDLINE | ID: mdl-33568638

RESUMEN

The global emergence of Zika virus (ZIKV) revealed the unprecedented ability for a mosquito-borne virus to cause congenital birth defects. A puzzling aspect of ZIKV emergence is that all human outbreaks and birth defects to date have been exclusively associated with the Asian ZIKV lineage, despite a growing body of laboratory evidence pointing towards higher transmissibility and pathogenicity of the African ZIKV lineage. Whether this apparent paradox reflects the use of relatively old African ZIKV strains in most laboratory studies is unclear. Here, we experimentally compare seven low-passage ZIKV strains representing the recently circulating viral genetic diversity. We find that recent African ZIKV strains display higher transmissibility in mosquitoes and higher lethality in both adult and fetal mice than their Asian counterparts. We emphasize the high epidemic potential of African ZIKV strains and suggest that they could more easily go unnoticed by public health surveillance systems than Asian strains due to their propensity to cause fetal loss rather than birth defects.


Asunto(s)
Infección por el Virus Zika/mortalidad , Infección por el Virus Zika/virología , Virus Zika/fisiología , Virus Zika/patogenicidad , Aedes/fisiología , Aedes/virología , África , Animales , Asia , Femenino , Humanos , Masculino , Ratones , Filogenia , Virulencia , Virus Zika/clasificación , Virus Zika/genética , Infección por el Virus Zika/transmisión
3.
Parasit Vectors ; 14(1): 76, 2021 Jan 22.
Artículo en Inglés | MEDLINE | ID: mdl-33482887

RESUMEN

BACKGROUND: On 11 March 2020, the World Health Organisation (WHO) declared the coronavirus disease 2019 (COVID-19) outbreak to be a pandemic. As the mosquito season progressed, the understandable concern that mosquitoes could transmit the virus began to increase among the general public and public health organisations. We have investigated the vector competence of Culex pipiens and Aedes albopictus, the two most common species of vector mosquitoes in Europe, for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Due to the very unusual feeding behaviour of Ae. albopictus, we also evaluated the role of this mosquito in a potential mechanical transmission of the virus. METHODS: For the vector competence study, mosquitoes were allowed to take several infectious blood meals. The mosquitoes were then collected and analysed at 0, 3, 7 and 10 days post-feeding. For the mechanical transmission test, Ae. albopictus females were allowed to feed for a short time on a feeder containing infectious blood and then on a feeder containing virus-free blood. Both mosquitoes and blood were tested for viral presence. RESULTS: Culex pipiens and Ae. albopictus were found not be competent vectors for SARS-CoV-2, and Ae. albopictus was unable to mechanically transmit the virus. CONCLUSIONS: This is the first study to show that the most common species of vector mosquitoes in Europe do not transmit SARS-CoV-2 and that Ae. albopictus is unable to mechanically transmit the virus from a positive host to a healthy host through host-feeding.


Asunto(s)
Aedes/virología , Culex/virología , Mosquitos Vectores/virología , /fisiología , Animales , Sangre/virología , Europa (Continente) , Femenino , ARN Viral/análisis , ARN Viral/aislamiento & purificación , Reacción en Cadena en Tiempo Real de la Polimerasa , Ovinos/sangre
4.
Nat Commun ; 12(1): 269, 2021 01 11.
Artículo en Inglés | MEDLINE | ID: mdl-33431834

RESUMEN

Chemical matter is needed to target the divergent biology associated with the different life cycle stages of Plasmodium. Here, we report the parallel de novo screening of the Medicines for Malaria Venture (MMV) Pandemic Response Box against Plasmodium asexual and liver stage parasites, stage IV/V gametocytes, gametes, oocysts and as endectocides. Unique chemotypes were identified with both multistage activity or stage-specific activity, including structurally diverse gametocyte-targeted compounds with potent transmission-blocking activity, such as the JmjC inhibitor ML324 and the antitubercular clinical candidate SQ109. Mechanistic investigations prove that ML324 prevents histone demethylation, resulting in aberrant gene expression and death in gametocytes. Moreover, the selection of parasites resistant to SQ109 implicates the druggable V-type H+-ATPase for the reduced sensitivity. Our data therefore provides an expansive dataset of compounds that could be redirected for antimalarial development and also point towards proteins that can be targeted in multiple parasite life cycle stages.


Asunto(s)
Antimaláricos/uso terapéutico , Descubrimiento de Drogas , Malaria/tratamiento farmacológico , Malaria/transmisión , Pandemias , Aedes/parasitología , Animales , Antimaláricos/química , Antimaláricos/farmacología , Análisis por Conglomerados , Relación Dosis-Respuesta a Droga , Células Hep G2 , Humanos , Concentración 50 Inhibidora , Estadios del Ciclo de Vida/efectos de los fármacos , Hígado/efectos de los fármacos , Hígado/parasitología , Malaria/epidemiología , Masculino , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/crecimiento & desarrollo
5.
PLoS Negl Trop Dis ; 15(1): e0008974, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-33428623

RESUMEN

In the last 20 years yellow fever (YF) has seen dramatic changes to its incidence and geographic extent, with the largest outbreaks in South America since 1940 occurring in the previously unaffected South-East Atlantic coast of Brazil in 2016-2019. While habitat fragmentation and land-cover have previously been implicated in zoonotic disease, their role in YF has not yet been examined. We examined the extent to which vegetation, land-cover, climate and host population predicted the numbers of months a location reported YF per year and by each month over the time-period. Two sets of models were assessed, one looking at interannual differences over the study period (2003-2016), and a seasonal model looking at intra-annual differences by month, averaging over the years of the study period. Each was fit using hierarchical negative-binomial regression in an exhaustive model fitting process. Within each set, the best performing models, as measured by the Akaike Information Criterion (AIC), were combined to create ensemble models to describe interannual and seasonal variation in YF. The models reproduced the spatiotemporal heterogeneities in YF transmission with coefficient of determination (R2) values of 0.43 (95% CI 0.41-0.45) for the interannual model and 0.66 (95% CI 0.64-0.67) for the seasonal model. For the interannual model, EVI, land-cover and vegetation heterogeneity were the primary contributors to the variance explained by the model, and for the seasonal model, EVI, day temperature and rainfall amplitude. Our models explain much of the spatiotemporal variation in YF in South America, both seasonally and across the period 2003-2016. Vegetation type (EVI), heterogeneity in vegetation (perhaps a proxy for habitat fragmentation) and land cover explain much of the trends in YF transmission seen. These findings may help understand the recent expansions of the YF endemic zone, as well as to the highly seasonal nature of YF.

6.
Viruses ; 13(1)2021 Jan 14.
Artículo en Inglés | MEDLINE | ID: mdl-33466915

RESUMEN

Mosquito-borne arthropod-borne viruses (arboviruses) such as the dengue virus (DENV), Zika virus (ZIKV), and chikungunya virus (CHIKV) are important human pathogens that are responsible for significant global morbidity and mortality. The recent emergence and re-emergence of mosquito-borne viral diseases (MBVDs) highlight the urgent need for safe and effective vaccines, therapeutics, and vector-control approaches to prevent MBVD outbreaks. In nature, arboviruses circulate between vertebrate hosts and arthropod vectors; therefore, disrupting the virus lifecycle in mosquitoes is a major approach for combating MBVDs. Several strategies were proposed to render mosquitoes that are refractory to arboviral infection, for example, those involving the generation of genetically modified mosquitoes or infection with the symbiotic bacterium Wolbachia. Due to the recent development of high-throughput screening methods, an increasing number of drugs with inhibitory effects on mosquito-borne arboviruses in mammalian cells were identified. These antivirals are useful resources that can impede the circulation of arboviruses between arthropods and humans by either rendering viruses more vulnerable in humans or suppressing viral infection by reducing the expression of host factors in mosquitoes. In this review, we summarize recent advances in small-molecule antiarboviral drugs in mammalian and mosquito cells, and discuss how to use these antivirals to block the transmission of MBVDs.


Asunto(s)
Aedes/virología , Antivirales/farmacología , Infecciones por Arbovirus/transmisión , Infecciones por Arbovirus/virología , Arbovirus/efectos de los fármacos , Mosquitos Vectores/virología , Aedes/efectos de los fármacos , Animales , Antivirales/química , Antivirales/uso terapéutico , Infecciones por Arbovirus/tratamiento farmacológico , Arbovirus/clasificación , Células Cultivadas , Descubrimiento de Drogas/métodos , Evaluación Preclínica de Medicamentos , Humanos , Control de Mosquitos/métodos , Enfermedades Transmitidas por Vectores/tratamiento farmacológico , Enfermedades Transmitidas por Vectores/transmisión , Enfermedades Transmitidas por Vectores/virología , Replicación Viral/efectos de los fármacos
7.
Nat Commun ; 12(1): 151, 2021 01 08.
Artículo en Inglés | MEDLINE | ID: mdl-33420058

RESUMEN

Mosquito-borne viruses threaten the Caribbean due to the region's tropical climate and seasonal reception of international tourists. Outbreaks of chikungunya and Zika have demonstrated the rapidity with which these viruses can spread. Concurrently, dengue fever cases have climbed over the past decade. Sustainable disease control measures are urgently needed to quell virus transmission and prevent future outbreaks. Here, to improve upon current control methods, we analyze temporal and spatial patterns of chikungunya, Zika, and dengue outbreaks reported in the Dominican Republic between 2012 and 2018. The viruses that cause these outbreaks are transmitted by Aedes mosquitoes, which are sensitive to seasonal climatological variability. We evaluate whether climate and the spatio-temporal dynamics of dengue outbreaks could explain patterns of emerging disease outbreaks. We find that emerging disease outbreaks were robust to the climatological and spatio-temporal constraints defining seasonal dengue outbreak dynamics, indicating that constant surveillance is required to prevent future health crises.


Asunto(s)
Fiebre Chikungunya/epidemiología , Enfermedades Transmisibles Emergentes/epidemiología , Dengue/epidemiología , Brotes de Enfermedades/estadística & datos numéricos , Enfermedades Endémicas/estadística & datos numéricos , Infección por el Virus Zika/epidemiología , Adolescente , Aedes/virología , Animales , Fiebre Chikungunya/prevención & control , Fiebre Chikungunya/transmisión , Fiebre Chikungunya/virología , Virus Chikungunya/aislamiento & purificación , Niño , Preescolar , Enfermedades Transmisibles Emergentes/prevención & control , Enfermedades Transmisibles Emergentes/transmisión , Enfermedades Transmisibles Emergentes/virología , Dengue/prevención & control , Dengue/transmisión , Dengue/virología , Virus del Dengue/aislamiento & purificación , Brotes de Enfermedades/prevención & control , República Dominicana/epidemiología , Enfermedades Endémicas/prevención & control , Monitoreo Epidemiológico , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Control de Mosquitos , Mosquitos Vectores/virología , Análisis Espacio-Temporal , Adulto Joven , Virus Zika/aislamiento & purificación , Infección por el Virus Zika/prevención & control , Infección por el Virus Zika/transmisión , Infección por el Virus Zika/virología
8.
Nat Commun ; 12(1): 595, 2021 01 26.
Artículo en Inglés | MEDLINE | ID: mdl-33500409

RESUMEN

Zika virus (ZIKV) emerged from obscurity in 2013 to spread from Asia to the South Pacific and the Americas, where millions of people were infected, accompanied by severe disease including microcephaly following congenital infections. Phylogenetic studies have shown that ZIKV evolved in Africa and later spread to Asia, and that the Asian lineage is responsible for the recent epidemics in the South Pacific and Americas. However, the reasons for the sudden emergence of ZIKV remain enigmatic. Here we report evolutionary analyses that revealed four mutations, which occurred just before ZIKV introduction to the Americas, represent direct reversions of previous mutations that accompanied earlier spread from Africa to Asia and early circulation there. Our experimental infections of Aedes aegypti mosquitoes, human cells, and mice using ZIKV strains with and without these mutations demonstrate that the original mutations reduced fitness for urban, human-amplifed transmission, while the reversions restored fitness, increasing epidemic risk. These findings include characterization of three transmission-adaptive ZIKV mutations, and demonstration that these and one identified previously restored fitness for epidemic transmission soon before introduction into the Americas. The initial mutations may have followed founder effects and/or drift when the virus was introduced decades ago into Asia.


Asunto(s)
Epidemias , Evolución Molecular , Aptitud Genética , Infección por el Virus Zika/epidemiología , Virus Zika/genética , Aedes/virología , África/epidemiología , Américas/epidemiología , Sustitución de Aminoácidos , Animales , Asia/epidemiología , Línea Celular , Modelos Animales de Enfermedad , Femenino , Fibroblastos , Humanos , Queratinocitos , Ratones , Mutación , Filogenia , Cultivo Primario de Células , Salud Urbana/estadística & datos numéricos , Virus Zika/patogenicidad , Infección por el Virus Zika/transmisión , Infección por el Virus Zika/virología
9.
Artículo en Inglés | MEDLINE | ID: mdl-33353025

RESUMEN

BACKGROUND: Dengue, a febrile illness, is caused by a Flavivirus transmitted by Aedes aegypti and Aedes albopictus mosquitoes. Climate influences the ecology of the vectors. We aimed to identify the influence of climatic variability on the occurrence of clinical dengue requiring hospitalization in Zone-5, a high incidence area of Dhaka City Corporation (DCC), Bangladesh. METHODS AND FINDINGS: We retrospectively identified clinical dengue cases hospitalized from Zone-5 of DCC between 2005 and 2009. We extracted records of the four major catchment hospitals of the study area. The Bangladesh Meteorological Department (BMD) provided data on temperature, rainfall, and humidity of DCC for the study period. We used autoregressive integrated moving average (ARIMA) models for the number of monthly dengue hospitalizations. We also modeled all the climatic variables using Poisson regression. During our study period, dengue occurred throughout the year in Zone-5 of DCC. The median number of hospitalized dengue cases was 9 per month. Dengue incidence increased sharply from June, and reached its peak in August. One additional rainy day per month increased dengue cases in the succeeding month by 6% (RR = 1.06, 95% CI: 1.04-1.09). CONCLUSIONS: Dengue is transmitted throughout the year in Zone-5 of DCC, with seasonal variation in incidence. The number of rainy days per month is significantly associated with dengue incidence in the subsequent month. Our study suggests the initiation of campaigns in DCC for controlling dengue and other Aedes mosquito borne diseases, including Chikunguniya from the month of May each year. BMD rainfall data may be used to determine campaign timing.


Asunto(s)
Aedes , Dengue , Lluvia , Animales , Bangladesh/epidemiología , Ciudades , Dengue/epidemiología , Dengue/transmisión , Hospitales , Mosquitos Vectores , Estudios Retrospectivos , Estaciones del Año
10.
PLoS Negl Trop Dis ; 14(12): e0008986, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-33370301

RESUMEN

Japanese encephalitis virus (JEV) is maintained in an enzootic cycle between swine, water birds, and mosquitoes. JEV has circulated indigenously in Asia, with Culex tritaeniorhynchus as the primary vector. In some areas where the primary vector is scarce or absent, sporadic cases of Japanese encephalitis have been reported, with Aedes japonicus japonicus presumed to have the potential as a secondary vector. As one of the world's most invasive culicid species, Ae. j. japonicus carries a considerable health risk for spreading diseases to wider areas, including Europe and North America. Thus, evaluation of its competency as a JEV vector, particularly in a native population, will be essential in preventing potential disease spread. In this study, the two mosquito species' vector competence in transmitting three JEV genotypes (I, III, and V) was assessed, with Cx. tritaeniorhynchus serving as a point of reference. The mosquitoes were virus-fed and the infection rate (IR), dissemination rate (DR), and transmission rate (TR) evaluated individually by either RT-qPCR or focus forming assay. Results showed striking differences between the two species, with IR of 95% (261/274) and 9% (16/177) in Cx. tritaeniorhynchus and Ae. j. japonicus, respectively. Both mosquitoes were susceptible to all three JEV genotypes with significant differences in IR and mean viral titer. Results confirm the primary vector's competence, but the fact that JEV was able to establish in Ae. j. japonicus is of public health significance, and with 2%-16% transmission rate it has the potential to successfully transmit JEV to the next host. This may explain the human cases and infrequent detection in primary vector-free areas. Importantly, Ae. j. japonicus could be a relevant vector spreading the disease into new areas, indicating the need for security measures in areas where the mosquito is distributed or where it may be introduced.


Asunto(s)
Aedes/virología , Culex/virología , Virus de la Encefalitis Japonesa (Especie)/crecimiento & desarrollo , Virus de la Encefalitis Japonesa (Especie)/aislamiento & purificación , Encefalitis Japonesa/transmisión , Mosquitos Vectores/virología , Animales , Asia/epidemiología , Línea Celular , Chlorocebus aethiops , Virus de la Encefalitis Japonesa (Especie)/genética , Encefalitis Japonesa/epidemiología , Genotipo , Humanos , Células Vero , Proteínas del Envoltorio Viral/genética
11.
PLoS Negl Trop Dis ; 14(12): e0008971, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-33338046

RESUMEN

Aedes aegypti is a vector of dengue, chikungunya, and Zika viruses. Current vector control strategies such as community engagement, source reduction, and insecticides have not been sufficient to prevent viral outbreaks. Thus, interest in novel strategies involving genetic engineering is growing. Female mosquitoes rely on flight to mate with males and obtain a bloodmeal from a host. We hypothesized that knockout of genes specifically expressed in female mosquitoes associated with the indirect flight muscles would result in a flightless female mosquito. Using CRISPR-Cas9 we generated loss-of-function mutations in several genes hypothesized to control flight in mosquitoes, including actin (AeAct-4) and myosin (myo-fem) genes expressed specifically in the female flight muscle. Genetic knockout of these genes resulted in 100% flightless females, with homozygous males able to fly, mate, and produce offspring, albeit at a reduced rate when compared to wild type males. Interestingly, we found that while AeAct-4 was haplosufficient, with most heterozygous individuals capable of flight, this was not the case for myo-fem, where about half of individuals carrying only one intact copy could not fly. These findings lay the groundwork for developing novel mechanisms of controlling Ae. aegypti populations, and our results suggest that this mechanism could be applicable to other vector species of mosquito.


Asunto(s)
Aedes/genética , Sistemas CRISPR-Cas , Insecticidas/farmacología , Control de Mosquitos , Mosquitos Vectores/genética , Infección por el Virus Zika/prevención & control , Virus Zika/fisiología , Aedes/fisiología , Aedes/virología , Animales , Femenino , Vuelo Animal , Técnicas de Inactivación de Genes , Humanos , Masculino , Mosquitos Vectores/fisiología , Mosquitos Vectores/virología , Fenotipo , Infección por el Virus Zika/transmisión , Infección por el Virus Zika/virología
12.
PLoS Negl Trop Dis ; 14(12): e0008867, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-33382725

RESUMEN

BACKGROUND: Aedes aegypti mosquito-borne viruses including Zika (ZIKV), dengue (DENV), yellow fever (YFV), and chikungunya (CHIKV) have emerged and re-emerged globally, resulting in an elevated burden of human disease. Aedes aegypti is found worldwide in tropical, sub-tropical, and temperate areas. The characterization of mosquito blood meals is essential to understand the transmission dynamics of mosquito-vectored pathogens. METHODOLOGY/PRINCIPAL FINDINGS: Here, we report Ae. aegypti and Culex quinquefasciatus host feeding patterns and arbovirus transmission in Northern Mexico using a metabarcoding-like approach with next-generation deep sequencing technology. A total of 145 Ae. aegypti yielded a blood meal analysis result with 107 (73.8%) for a single vertebrate species and 38 (26.2%) for two or more. Among the single host blood meals for Ae. aegypti, 28.0% were from humans, 54.2% from dogs, 16.8% from cats, and 1.0% from tortoises. Among those with more than one species present, 65.9% were from humans and dogs. For Cx. quinquefasciatus, 388 individuals yielded information with 326 (84%) being from a single host and 63 (16.2%) being from two or more hosts. Of the single species blood meals, 77.9% were from dogs, 6.1% from chickens, 3.1% from house sparrows, 2.4% from humans, while the remaining 10.5% derived from other 12 host species. Among those which had fed on more than one species, 11% were from dogs and humans, and 89% of other host species combinations. Forage ratio analysis revealed dog as the most over-utilized host by Ae. aegypti (= 4.3) and Cx. quinquefasciatus (= 5.6) and the human blood index at 39% and 4%, respectively. A total of 2,941 host-seeking female Ae. aegypti and 3,536 Cx. quinquefasciatus mosquitoes were collected in the surveyed area. Of these, 118 Ae. aegypti pools and 37 Cx. quinquefasciatus pools were screened for seven arboviruses (ZIKV, DENV 1-4, CHIKV, and West Nile virus (WNV)) using qRT-PCR and none were positive (point prevalence = 0%). The 95%-exact upper limit confidence interval was 0.07% and 0.17% for Ae. aegypti and Cx. quinquefasciatus, respectively. CONCLUSIONS/SIGNIFICANCE: The low human blood feeding rate in Ae. aegypti, high rate of feeding on mammals by Cx. quinquefasciatus, and the potential risk to transmission dynamics of arboviruses in highly urbanized areas of Northern Mexico is discussed.


Asunto(s)
Aedes/virología , Infecciones por Arbovirus/veterinaria , Arbovirus/fisiología , Culex/virología , Vertebrados/virología , Animales , Infecciones por Arbovirus/sangre , Infecciones por Arbovirus/transmisión , Código de Barras del ADN Taxonómico , Conducta Alimentaria , Secuenciación de Nucleótidos de Alto Rendimiento , Interacciones Huésped-Patógeno , Modelos Biológicos , Mosquitos Vectores/virología , Especificidad de la Especie , Vertebrados/sangre
13.
PLoS Pathog ; 16(12): e1009134, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-33351855

RESUMEN

Mosquitoes are responsible for the transmission of many clinically important arboviruses that cause significant levels of annual mortality and socioeconomic health burden worldwide. Deciphering the mechanisms by which mosquitoes modulate arbovirus infection is crucial to understand how viral-host interactions promote vector transmission and human disease. SUMOylation is a post-translational modification that leads to the covalent attachment of the Small Ubiquitin-like MOdifier (SUMO) protein to host factors, which in turn can modulate their stability, interaction networks, sub-cellular localisation, and biochemical function. While the SUMOylation pathway is known to play a key role in the regulation of host immune defences to virus infection in humans, the importance of this pathway during arbovirus infection in mosquito vectors, such as Aedes aegypti (Ae. aegypti), remains unknown. Here we characterise the sequence, structure, biochemical properties, and tissue-specific expression profiles of component proteins of the Ae. aegypti SUMOylation pathway. We demonstrate significant biochemical differences between Ae. aegypti and Homo sapiens SUMOylation pathways and identify cell-type specific patterns of SUMO expression in Ae. aegypti tissues known to support arbovirus replication. Importantly, depletion of core SUMOylation effector proteins (SUMO, Ubc9 and PIAS) in Ae. aegypti cells led to enhanced levels of arbovirus replication from three different families; Zika (Flaviviridae), Semliki Forest (Togaviridae), and Bunyamwera (Bunyaviridae) viruses. Our findings identify an important role for mosquito SUMOylation in the cellular restriction of arboviruses that may directly influence vector competence and transmission of clinically important arboviruses.


Asunto(s)
Aedes/virología , Arbovirus/fisiología , Interacciones Huésped-Patógeno/fisiología , Mosquitos Vectores/virología , Replicación Viral/fisiología , Animales , Infecciones por Arbovirus/transmisión , Humanos , Sumoilación
14.
PLoS Pathog ; 16(12): e1009068, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-33382858

RESUMEN

Originating from African forests, Zika virus (ZIKV) has now emerged worldwide in urbanized areas, mainly transmitted by Aedes aegypti mosquitoes. Although Aedes albopictus can transmit ZIKV experimentally and was suspected to be a ZIKV vector in Central Africa, the potential of this species to sustain virus transmission was yet to be uncovered until the end of 2019, when several autochthonous transmissions of the virus vectored by Ae. albopictus occurred in France. Aside from these few locally acquired ZIKV infections, most territories colonized by Ae. albopictus have been spared so far. The risk level of ZIKV emergence in these areas remains however an open question. To assess Ae. albopictus' vector potential for ZIKV and identify key virus outbreak predictors, we built a complete framework using the complementary combination of (i) dose-dependent experimental Ae. albopictus exposure to ZIKV followed by time-dependent assessment of infection and systemic infection rates, (ii) modeling of intra-human ZIKV viremia dynamics, and (iii) in silico epidemiological simulations using an Agent-Based Model. The highest risk of transmission occurred during the pre-symptomatic stage of the disease, at the peak of viremia. At this dose, mosquito infection probability was estimated to be 20%, and 21 days were required to reach the median systemic infection rates. Mosquito population origin, either temperate or tropical, had no impact on infection rates or intra-host virus dynamic. Despite these unfavorable characteristics for transmission, Ae. albopictus was still able to trigger and yield large outbreaks in a simulated environment in the presence of sufficiently high mosquito biting rates. Our results reveal a low but existing epidemic potential of Ae. albopictus for ZIKV, that might explain the absence of large scale ZIKV epidemics so far in territories occupied only by Ae. albopictus. They nevertheless support active surveillance and eradication programs in these territories to maintain the risk of emergence to a low level.


Asunto(s)
Mosquitos Vectores/metabolismo , Mosquitos Vectores/virología , Infección por el Virus Zika/transmisión , Aedes/metabolismo , Aedes/virología , Animales , Brotes de Enfermedades , Vectores de Enfermedades , Epidemias , Humanos , Modelos Teóricos , Saliva/virología , Carga Viral , Viremia/transmisión , Virus Zika/patogenicidad , Infección por el Virus Zika/epidemiología , Infección por el Virus Zika/virología
15.
Nat Commun ; 11(1): 5801, 2020 11 16.
Artículo en Inglés | MEDLINE | ID: mdl-33199712

RESUMEN

Historically endemic to Sub-Saharan Africa and South America, yellow fever is absent from the Asia-Pacific region. Yellow fever virus (YFV) is mainly transmitted by the anthropophilic Aedes mosquitoes whose distribution encompasses a large belt of tropical and sub tropical regions. Increasing exchanges between Africa and Asia have caused imported YFV incidents in non-endemic areas, which are threatening Asia with a new viral emergence. Here, using experimental infections of field-collected mosquitoes, we show that Asian-Pacific Aedes mosquitoes are competent vectors for YFV. We observe that Aedes aegypti populations from Singapore, Taiwan, Thailand, and New Caledonia are capable of transmitting YFV 14 days after oral infections, with a number of viral particles excreted from saliva reaching up to 23,000 viral particles. These findings represent the most comprehensive assessment of vector competence and show that Ae. aegypti mosquitoes from the Asia-Pacific region are highly competent to YFV, corroborating that vector populations are seemingly not a brake to the emergence of yellow fever in the region.


Asunto(s)
Fiebre Amarilla/transmisión , Fiebre Amarilla/virología , Virus de la Fiebre Amarilla/fisiología , Aedes/virología , Animales , Asia/epidemiología , Geografía , Insectos Vectores/virología , Modelos Lineales , Probabilidad , Factores de Riesgo , Saliva/virología , Carga Viral
16.
BMC Public Health ; 20(1): 1385, 2020 Sep 11.
Artículo en Inglés | MEDLINE | ID: mdl-32912177

RESUMEN

BACKGROUND: In El Salvador, Aedes aegypti mosquitoes transmitting Zika and other arboviruses use water storage containers as important oviposition sites. Promotion of water storage container cleaning is a key element of prevention programs. We explored community perceptions surrounding cleaning practices among pregnant women, male partners of pregnant women, and women likely to become pregnant. METHODS: Researchers conducted 11 focus groups and 12 in-depth interviews which included individual elicitations of Zika prevention measures practiced in the community. Focus group participants rated 18 images depicting Zika-related behaviors according to effectiveness and feasibility in the community context, discussed influencing determinants, voted on community intentions to perform prevention behaviors, and performed washbasin cleaning simulations. In-depth interviews with male partners of pregnant women used projective techniques with images to explore their perceptions on a subset of Zika prevention behaviors. RESULTS: General cleaning of the home, to ensure a healthy environment, was a strong community norm. In this context, participants gave water storage container cleaning a high rating, for both its effectiveness and feasibility. Participants were convinced that they cleaned their water storage containers effectively against Zika, but their actual skills were inadequate to destroy Aedes aegypti eggs. A further constraint was the schedule of water availability. Even during pregnancy, male partners rarely cleaned water storage containers because water became available in homes when they were at work. Furthermore, prevailing gender norms did not foster male participation in domestic cleaning activities. Despite these factors, many men were willing to provide substantial support with cleaning when their partners were pregnant, in order to protect their family. CONCLUSIONS: Behavior change programs for the prevention of Zika and other arboviruses need to improve community members' mosquito egg destruction skills rather than perpetuate the promotion of non-specific cleaning in and around the home as effective. Egg elimination must be clearly identified as the objective of water storage container maintenance and programs should highlight the effective techniques to achieve this goal. In addition, programs must build the skills of family members who support pregnant women to maintain the frequency of effective egg destruction in all water storage containers of the home.


Asunto(s)
Aedes/virología , Conocimientos, Actitudes y Práctica en Salud , Control de Mosquitos/métodos , Abastecimiento de Agua , Agua , Infección por el Virus Zika/prevención & control , Virus Zika , Adolescente , Adulto , Animales , El Salvador , Femenino , Grupos Focales , Humanos , Masculino , Persona de Mediana Edad , Embarazo , Investigación Cualitativa , Características de la Residencia , Adulto Joven , Virus Zika/crecimiento & desarrollo , Infección por el Virus Zika/transmisión , Infección por el Virus Zika/virología
17.
PLoS Negl Trop Dis ; 14(9): e0008614, 2020 09.
Artículo en Inglés | MEDLINE | ID: mdl-32956355

RESUMEN

The emergence of mosquito-transmitted viruses poses a global threat to human health. Combining mechanistic epidemiological models based on temperature-trait relationships with climatological data is a powerful technique for environmental risk assessment. However, a limitation of this approach is that the local microclimates experienced by mosquitoes can differ substantially from macroclimate measurements, particularly in heterogeneous urban environments. To address this scaling mismatch, we modeled spatial variation in microclimate temperatures and the thermal potential for dengue transmission by Aedes albopictus across an urban-to-rural gradient in Athens-Clarke County GA. Microclimate data were collected across gradients of tree cover and impervious surface cover. We developed statistical models to predict daily minimum and maximum microclimate temperatures using coarse-resolution gridded macroclimate data (4000 m) and high-resolution land cover data (30 m). The resulting high-resolution microclimate maps were integrated with temperature-dependent mosquito abundance and vectorial capacity models to generate monthly predictions for the summer and early fall of 2018. The highest vectorial capacities were predicted for patches of trees in urban areas with high cover of impervious surfaces. Vectorial capacity was most sensitive to tree cover during the summer and became more sensitive to impervious surfaces in the early fall. Predictions from the same models using temperature data from a local meteorological station consistently over-predicted vectorial capacity compared to the microclimate-based estimates. This work demonstrates that it is feasible to model variation in mosquito microenvironments across an urban-to-rural gradient using satellite Earth observations. Epidemiological models applied to the microclimate maps revealed localized patterns of temperature suitability for disease transmission that would not be detectable using macroclimate data. Incorporating microclimate data into disease transmission models has the potential to yield more spatially precise and ecologically interpretable metrics of mosquito-borne disease transmission risk in urban landscapes.


Asunto(s)
Aedes/virología , Dengue/epidemiología , Dengue/transmisión , Mosquitos Vectores/virología , Animales , Arbovirus/patogenicidad , Virus del Dengue/patogenicidad , Ecosistema , Georgia/epidemiología , Humanos , Microclima , Modelos Biológicos , Árboles
18.
Sci Rep ; 10(1): 15751, 2020 09 25.
Artículo en Inglés | MEDLINE | ID: mdl-32978448

RESUMEN

Yellow Fever (YF) is a severe disease caused by Yellow Fever Virus (YFV), endemic in some parts of Africa and America. In Brazil, YFV is maintained by a sylvatic transmission cycle involving non-human primates (NHP) and forest canopy-dwelling mosquitoes, mainly Haemagogus-spp and Sabethes-spp. Beginning in 2016, Brazil faced one of the largest Yellow Fever (YF) outbreaks in recent decades, mainly in the southeastern region. In São Paulo city, YFV was detected in October 2017 in Aloutta monkeys in an Atlantic Forest area. From 542 NHP, a total of 162 NHP were YFV positive by RT-qPCR and/or immunohistochemistry, being 22 Callithrix-spp. most from urban areas. Entomological collections executed did not detect the presence of strictly sylvatic mosquitoes. Three mosquito pools were positive for YFV, 2 Haemagogus leucocelaenus, and 1 Aedes scapularis. In summary, YFV in the São Paulo urban area was detected mainly in resident marmosets, and synanthropic mosquitoes were likely involved in viral transmission.

19.
PLoS Negl Trop Dis ; 14(9): e0008576, 2020 09.
Artículo en Inglés | MEDLINE | ID: mdl-32881865

RESUMEN

BACKGROUND: The ability of cluster-randomized trials to capture mass or indirect effects is one reason for their increasing use to test interventions against vector-borne diseases such as malaria and dengue. For the same reason, however, the independence of clusters may be compromised if the distances between clusters is too small to ensure independence. In other words they may be subject to spillover effects. METHODS: We distinguish two types of spatial spillover effect: between-cluster dependence in outcomes, or spillover dependence; and modification of the intervention effect according to distance to the intervention arm, or spillover indirect effect. We estimate these effects in trial of insecticide-treated materials against the dengue mosquito vector, Aedes aegypti, in Venezuela, the endpoint being the Breteau index. We use a novel random effects Poisson spatial regression model. Spillover dependence is incorporated via an orthogonalized intrinsic conditional autoregression (ICAR) model. Spillover indirect effects are incorporated via the number of locations within a certain radius, set at 200m, that are in the intervention arm. RESULTS: From the model with ICAR spatial dependence, and the degree of surroundedness, the intervention effect is estimated as 0.74-favouring the intervention-with a 95% credible interval of 0.34 to 1.69. The point estimates are stronger with increasing surroundedness within intervention locations. CONCLUSION: In this trial there is some evidence of a spillover indirect effect of the intervention, with the Breteau index tending to be lower in locations which are more surrounded by locations in the intervention arm.


Asunto(s)
Aedes/efectos de los fármacos , Insecticidas/farmacología , Control de Mosquitos/métodos , Mosquitos Vectores/efectos de los fármacos , Aedes/fisiología , Animales , Dengue/transmisión , Humanos , Mosquitos Vectores/fisiología , Análisis Espacial , Venezuela
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...