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Since the Zika virus (ZIKV) pandemic in 2015-2017, there has been a near absence of reported cases in the Americas outside of Brazil. However, the conditions for Aedes-borne transmission persist in Latin America, and the threat of ZIKV transmission is increasing as population immunity wanes. Mexico has reported only 70 cases of laboratory-confirmed ZIKV infection since 2020, with no cases recorded in the Yucatán peninsula. Here, we provide evidence of active ZIKV transmission, despite the absence of official case reports, in the city of Mérida, Mexico, the capital of the state of Yucatán. Capitalizing on an existing cohort, we detected cases in participants with symptoms consistent with flavivirus infection from 2021 to 2022. Serum samples from suspected cases were tested for ZIKV RNA by polymerase chain reaction or ZIKV-reactive IgM by ELISA. To provide more specific evidence of exposure, focus reduction neutralization tests were performed on ELISA-positive samples. Overall, we observed 25 suspected ZIKV infections for an estimated incidence of 2.8 symptomatic cases per 1,000 persons per year. Our findings emphasize the continuing threat of ZIKV transmission in the setting of decreased surveillance and reporting.
Assuntos
Aedes , Infecção por Zika virus , Zika virus , Animais , Humanos , México/epidemiologia , América/epidemiologiaRESUMO
Aedes aegypti is a mosquito that transmits viral diseases such as dengue, chikungunya, Zika, and yellow fever. The insect's microbiota is recognized for regulating several biological processes, including digestion, metabolism, egg production, development, and immune response. However, the role of the bacteria involved in insecticide susceptibility has not been established. Therefore, the objective of this study was to characterize the resident microbiota in a field population of A. aegypti to evaluate its role associated with susceptibility to the insecticides permethrin and deltamethrin. Mosquitoes were fed 10% sucrose mixed with antibiotics and then exposed to insecticides using a diagnostic dose. DNA was extracted, and sequencing of bacterial 16S rRNA was carried out on Illumina® MiSeq™. Proteobacteria (92.4%) and Bacteroidetes (7.6%) were the phyla, which are most abundant in mosquitoes fed with sucrose 10%. After exposure to permethrin, the most abundant bacterial species were Pantoea agglomerans (38.4%) and Pseudomonas azotoformans-fluorescens-synxantha (14.2%). Elizabethkingia meningoseptica (38.4%) and Ps. azotoformans-fluorescens-synxantha (26.1%) were the most abundant after exposure to deltamethrin. Our results showed a decrease in mosquitoes' survival when exposed to permethrin, while no difference in survival when exposed to deltamethrin when the microbiota was modified. We found that the change in microbiota modifies the response of mosquitoes to permethrin. These results are essential for a better understanding of mosquito physiology in response to insecticides.
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Several vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been approved for controlling the coronavirus disease 2019 (COVID-19) pandemic worldwide. Antibody response is essential to understand the immune response to different viral targets after vaccination with different vaccine platforms. Thus, the main aim of this study was to describe how vaccination with two distinct SARS-CoV-2 vaccine preparations elicit IgG antibody specific responses against two antigenically relevant SARS-CoV-2 viral proteins: the receptor-binding domain (RBD) and the full-length spike (S). To do so, SARS-CoV-2 protein specific in-house enzyme-linked immunosorbent assays (ELISAs) were standardized and tested against serum samples collected from 89 adults, recipients of either a single-dose of the Spike-encoding mRNA-based Pfizer/BioNTech (Pf-BNT) (70%, 62/89) or the Spike-encoding-Adenovirus-5-based CanSino Biologics Inc. (CSBIO) (30%, 27/89) in Merida, Mexico. Overall, we identified an IgG seroconversion rate of 88% (68/78) in all vaccinees after more than 25 days post-vaccination (dpv). Anti-RBD IgG-specific responses ranged from 90% (46/51) in the Pf-BNT vaccine at 25 dpv to 74% (20/27) in the CSBIO vaccine at 42 dpv. Compared to the S, the RBD IgG reactivity was significantly higher in both Pf-BNT (p < 0.004) and CSBIO (p < 0.003) vaccinees. Interestingly, in more than 50% of vaccine recipients, with no history of COVID-19 infection, antibodies against the nucleocapsid (N) protein were detected. Thus, participants were grouped either as naïve or pre-exposed vaccinees. Seroconversion rates after 25 and more dpv varies between 100% in Pf-BNT (22/22) and 75% (9/12) in CSBIO pre-exposed vaccinees, and 89% (26/29) and 73% (11/15) in Pf-BNT and CSBIO naïve vaccine recipients, respectively. In summary, observed seroconversion rates varied depending on the type of vaccine, previous infection with SARS-CoV-2, and the target viral antigen. Our results indicate that both vaccine preparations can induce detectable levels of IgG against the RBD or Spike in both naïve and SARS-CoV-2 pre-exposed vaccinees. Our study provides valuable and novel information about the serodiagnosis and the antibody response to vaccines in Mexico.
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Aedes-borne viruses (ABVs) such as dengue (DENV), chikungunya (CHIKV), and Zika (ZIKV) contribute significantly to the global burden of infectious diseases, disproportionately affecting disadvantaged populations from tropical and subtropical urban areas. ABVs can be transmitted from female mosquitoes to their progeny by vertical transmission via transovarial and/or trans-egg vertical transmission and contribute to the maintenance of infected-mosquito populations year-round in endemic regions. This study describes the natural infection rate of DENV, CHIKV, and ZIKV in field-caught male Aedes (Sergentomyia) aegypti (Linnaeus) mosquitoes from Mérida, Yucatán, México, as a proxy for the occurrence of vertical virus transmission. We used indoor sequential sampling with Prokopack aspirators to collect all mosquitoes inside houses from ABV hotspots areas. Collections were performed in a DENV and CHIKV post-epidemic phase and during a period of active ZIKV transmission. We individually RT-qPCR tested all indoor collected Ae. aegypti males (1,278) followed by Sanger sequencing analysis for final confirmation. A total of 6.7% male mosquitoes were positive for ABV (CHIKV = 5.7%; DENV = 0.9%; ZIKV = 0.1%) and came from 21.0% (30/143) houses infested with males. Most ABV-positive male mosquitoes were positive for CHIKV (84.8%). The distribution of ABV-positive Ae. aegypti males was aggregated in a few households, with two houses having 11 ABV-positive males each. We found a positive association between ABV-positive males and females per house. These findings suggested the occurrence of vertical arbovirus transmission within the mosquito populations in an ABV-endemic area and, a mechanism contributing to viral maintenance and virus re-emergence among humans in post-epidemic periods.
Assuntos
Aedes , Febre de Chikungunya , Infecção por Zika virus , Zika virus , Animais , Feminino , Humanos , Masculino , México , Mosquitos VetoresRESUMO
BACKGROUND: The combination of Wolbachia-based incompatible insect technique (IIT) and radiation-based sterile insect technique (SIT) can be used for population suppression of Aedes aegypti. Our main objective was to evaluate whether open-field mass-releases of wAlbB-infected Ae. aegypti males, as part of an Integrated Vector Management (IVM) plan led by the Mexican Ministry of Health, could suppress natural populations of Ae. aegypti in urbanized settings in south Mexico. METHODOLOGY/PRINCIPAL FINDINGS: We implemented a controlled before-and-after quasi-experimental study in two suburban localities of Yucatan (Mexico): San Pedro Chimay (SPC), which received IIT-SIT, and San Antonio Tahdzibichén used as control. Release of wAlbB Ae. aegypti males at SPC extended for 6 months (July-December 2019), covering the period of higher Ae. aegypti abundance. Entomological indicators included egg hatching rates and outdoor/indoor adult females collected at the release and control sites. Approximately 1,270,000 lab-produced wAlbB-infected Ae. aegypti males were released in the 50-ha treatment area (2,000 wAlbB Ae. aegypti males per hectare twice a week in two different release days, totaling 200,000 male mosquitoes per week). The efficacy of IIT-SIT in suppressing indoor female Ae. aegypti density (quantified from a generalized linear mixed model showing a statistically significant reduction in treatment versus control areas) was 90.9% a month after initiation of the suppression phase, 47.7% two months after (when number of released males was reduced in 50% to match local abundance), 61.4% four months after (when initial number of released males was re-established), 88.4% five months after and 89.4% at six months after the initiation of the suppression phase. A proportional, but lower, reduction in outdoor female Ae. aegypti was also quantified (range, 50.0-75.2% suppression). CONCLUSIONS/SIGNIFICANCE: Our study, the first open-field pilot implementation of Wolbachia IIT-SIT in Mexico and Latin-America, confirms that inundative male releases can significantly reduce natural populations of Ae. aegypti. More importantly, we present successful pilot results of the integration of Wolbachia IIT-SIT within a IVM plan implemented by Ministry of Health personnel.
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Aedes , Infertilidade Masculina , Wolbachia , Animais , Feminino , Humanos , Insetos , Masculino , México , Controle de Mosquitos/métodos , Mosquitos Vetores , Projetos PilotoRESUMO
The prevalence of SARS-CoV-2 exposure in children during the global COVID-19 pandemic has been underestimated due to lack of testing and the relatively mild symptoms in adolescents. Understanding the exposure rates in the pediatric population is essential as children are the last to receive vaccines and can act as a source for SARS-CoV-2 mutants that may threaten vaccine escape. This cross-sectional study aims to quantify the prevalence of anti-SARS-CoV-2 serum antibodies in children in a major city in México in the Spring of 2021 and determine if there are any demographic or socioeconomic correlating factors. We obtained socioeconomic information and blood samples from 1,005 children from 50 neighborhood clusters in Mérida, Yucatán, México. We then tested the sera of these participants for anti-SARS-CoV-2 IgG and IgM antibodies using lateral flow immunochromatography. We found that 25.5% of children in our cohort were positive for anti-SARS-CoV-2 antibodies and there was no correlation between age and antibody prevalence. Children that lived with large families were statistically more likely to have antibodies against SARS-CoV-2. Spatial analyses identified two hotspots of high SARS-CoV-2 seroprevalence in the west of the city. These results indicate that a large urban population of unvaccinated children has been exposed to SARS-CoV-2 and that a major correlating factor was the number of people within the child's household with a minor correlation with particular geographical hotspots. There is also a larger population of children that may be susceptible to future infection upon easing of social distancing measures. These findings suggest that in future pandemic scenarios, limited public health resources can be best utilized on children living in large households in urban areas.
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After the tropical storm Cristobal, we performed special adult entomological collections in the peri-domicile of 35 houses from 25 neighborhoods of Mérida, Yucatan, Mexico in response to complaints from the community about an increased nuisance due to an abundance of mosquitoes. A total of 1,275 specimens from four genera and 13 species were collected: Aedes taeniorhynchus (92%), Culex quinquefasciatus (72%), Aedes aegypti (72%), Psorophora mexicana (36%), Psorophora cyanescens (32%), Aedes scapularis (24%), Culex nigripalpus (24%), Aedes albopictus (8%), Psorophora ferox (4%), Haemagogus equinus (4%), Aedes trivittatus (4%), Culex coronator (4%), Culex iolambdis (4%). From these collections, the increased mosquito nuisance was mainly the result of invasive species such as Aedes taeniorhynchus and Psorophora. City wide, vehicle mounted ULV spraying was performed by the MoH and the municipality of Merida to control adult mosquito populations. We report Culex iolambdis for the first time in Merida and Psorophora mexicana for the state of Yucatan.
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OBJECTIVE: To evaluate the protective effect of house screening (HS) on indoor Aedes aegypti infestation, abundance and arboviral infection in Merida, Mexico. METHODS: In 2019, we performed a cluster randomised controlled trial (6 control and 6 intervention areas: 100 households/area). Intervention clusters received permanently fixed fiberglass HS on all windows and doors. The study included two cross-sectional entomologic surveys, one baseline (dry season in May 2019) and one post-intervention (PI, rainy season between September and October 2019). The presence and number of indoor Aedes females and blood-fed females (indoor mosquito infestation) as well as arboviral infections with dengue (DENV) and Zika (ZIKV) viruses were evaluated in a subsample of 30 houses within each cluster. RESULTS: HS houses had significantly lower risk for having Aedes aegypti female mosquitoes (odds ratio [OR] = 0.56, 95% CI 0.33-0.97, p = 0.04) and blood-fed females (OR = 0.53, 95% CI 0.28-0.97, p = 0.04) than unscreened households from the control arm. Compared to control houses, HS houses had significantly lower indoor Ae. aegypti abundance (rate ratio [RR] = 0.50, 95% CI 0.30-0.83, p = 0.01), blood-fed Ae. aegypti females (RR = 0.48, 95% CI 0.27-0.85, p = 0.01) and female Ae. aegypti positive for arboviruses (OR = 0.29, 95% CI 0.10-0.86, p = 0.02). The estimated intervention efficacy in reducing Ae. aegypti arbovirus infection was 71%. CONCLUSIONS: These results provide evidence supporting the use of HS as an effective pesticide-free method to control house infestations with Aedes aegypti and reduce the transmission of Aedes-transmitted viruses such as DENV, chikungunya (CHIKV) and ZIKV.
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Aedes/fisiologia , Habitação , Controle de Mosquitos/métodos , Aedes/virologia , Animais , Análise por Conglomerados , Estudos Transversais , Vírus da Dengue/isolamento & purificação , Feminino , Interações Hospedeiro-Patógeno , Humanos , México , Zika virus/isolamento & purificaçãoRESUMO
Arbovirus infection in Aedes aegypti has historically been quantified from a sample of the adult population by pooling collected mosquitoes to increase detectability. However, there is a significant knowledge gap about the magnitude of natural arbovirus infection within areas of active transmission, as well as the sensitivity of detection of such an approach. We used indoor Ae. aegypti sequential sampling with Prokopack aspirators to collect all mosquitoes inside 200 houses with suspected active ABV transmission from the city of Mérida, Mexico, and tested all collected specimens by RT-PCR to quantify: a) the absolute arbovirus infection rate in individually tested Ae. aegypti females; b) the sensitivity of using Prokopack aspirators in detecting ABV-infected mosquitoes; and c) the sensitivity of entomological inoculation rate (EIR) and vectorial capacity (VC), two measures ABV transmission potential, to different estimates of indoor Ae. aegypti abundance. The total number of Ae. aegypti (total catch, the sum of all Ae. aegypti across all collection intervals) as well as the number on the first 10-min of collection (sample, equivalent to a routine adult aspiration session) were calculated. We individually tested by RT-PCR 2,161 Aedes aegypti females and found that 7.7% of them were positive to any ABV. Most infections were CHIKV (77.7%), followed by DENV (11.4%) and ZIKV (9.0%). The distribution of infected Aedes aegypti was overdispersed; 33% houses contributed 81% of the infected mosquitoes. A significant association between ABV infection and Ae. aegypti total catch indoors was found (binomial GLMM, Odds Ratio > 1). A 10-min indoor Prokopack collection led to a low sensitivity of detecting ABV infection (16.3% for detecting infected mosquitoes and 23.4% for detecting infected houses). When averaged across all infested houses, mean EIR ranged between 0.04 and 0.06 infective bites per person per day, and mean VC was 0.6 infectious vectors generated from a population feeding on a single infected host per house/day. Both measures were significantly and positively associated with Ae. aegypti total catch indoors. Our findings provide evidence that the accurate estimation and quantification of arbovirus infection rate and transmission risk is a function of the sampling effort, the local abundance of Aedes aegypti and the intensity of arbovirus circulation.
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Aedes/virologia , Infecções por Arbovirus/epidemiologia , Mosquitos Vetores/virologia , Animais , Infecções por Arbovirus/diagnóstico , Infecções por Arbovirus/transmissão , Feminino , Masculino , Densidade DemográficaRESUMO
This study reports the results of a molecular screening for Wolbachia (Wb) infection in Aedes albopictus (Skuse) populations recently established in the Yucatan Peninsula, Mexico. To do so, collections of free-flying adults with BG traps and emerged adults from eggs after ovitrap field collections were performed in three suburban localities of the city of Merida, Yucatan. Overall, local populations of Ae. albopictus present a natural Wb infection rate of ~40% (18 of 45). Wb infection was detected in both field-collected adults (76.5%, 13 of 17) and eggs reared (17.8%, 5 of 28) and in 37.9% (11/29) of females and 43.7% (7/16) of male Ae. albopictus mosquitoes. An initial screening for Wolbachia strain typing showed that native Ae. albopictus were naturally coinfected with both wAlbA and wAlbB strains. The knowledge of the prevalence and diversity of Wolbachia strains in local populations of Aedes mosquitoes is part of the baseline information required for current and future Wolbachia-based vector control approaches to be conducted in Mexico.
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Aedes/microbiologia , Wolbachia/isolamento & purificação , Animais , México , Mosquitos Vetores/microbiologia , Patologia MolecularRESUMO
Severe dengue pathogenesis is not fully understood, but high levels of proinflammatory cytokines have been associated with dengue disease severity. In this study, the cytokine levels in 171 sera from Mexican patients with primary dengue fever (DF) and dengue haemorrhagic fever (DHF) from dengue virus (DENV) 1 (n = 116) or 2 (n = 55) were compared. DF and DHF were defined according to the patient's clinical condition, the primary infections as indicated by IgG enzymatic immunoassay negative results, and the infecting serotype as assessed by real-time reverse transcription-polymerase chain reaction. Samples were analysed for circulating levels of interleukin (IL)-12p70, interferon (IFN)-γ, tumour necrosis factor (TNF)-α, IL-6, and IL-8 using a commercial cytometric bead array. Significantly higher IFN-γ levels were found in patients with DHF than those with DF. However, significantly higher IL-12p70, TNF-α, and IL-6 levels were associated with DHF only in patients who were infected with DENV2 but not with DENV1. Moreover, patients with DF who were infected with DENV1 showed higher levels of IL-12p70, TNF-α, and IL-6 than patients with DHF early after-fever onset. The IL-8 levels were similar in all cases regardless of the clinical condition or infection serotype. These results suggest that the association between high proinflammatory cytokine levels and dengue disease severity does not always stand, and it once again highlights the complex nature of DHF pathogenesis.
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Citocinas/metabolismo , Vírus da Dengue/imunologia , Dengue Grave/imunologia , Dengue/imunologia , Vírus da Dengue/classificação , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Mediadores da Inflamação/metabolismo , Interferon gama/sangue , Interleucina-12/sangue , Interleucina-6/sangue , Interleucina-8/sangue , Masculino , México , Reação em Cadeia da Polimerase em Tempo Real/métodos , Sorogrupo , Dengue Grave/sangue , Estatísticas não Paramétricas , Fator de Necrose Tumoral alfa/sangueRESUMO
Severe dengue pathogenesis is not fully understood, but high levels of proinflammatory cytokines have been associated with dengue disease severity. In this study, the cytokine levels in 171 sera from Mexican patients with primary dengue fever (DF) and dengue haemorrhagic fever (DHF) from dengue virus (DENV) 1 (n = 116) or 2 (n = 55) were compared. DF and DHF were defined according to the patient’s clinical condition, the primary infections as indicated by IgG enzymatic immunoassay negative results, and the infecting serotype as assessed by real-time reverse transcription-polymerase chain reaction. Samples were analysed for circulating levels of interleukin (IL)-12p70, interferon (IFN)-γ, tumour necrosis factor (TNF)-α, IL-6, and IL-8 using a commercial cytometric bead array. Significantly higher IFN-γ levels were found in patients with DHF than those with DF. However, significantly higher IL-12p70, TNF-α, and IL-6 levels were associated with DHF only in patients who were infected with DENV2 but not with DENV1. Moreover, patients with DF who were infected with DENV1 showed higher levels of IL-12p70, TNF-α, and IL-6 than patients with DHF early after-fever onset. The IL-8 levels were similar in all cases regardless of the clinical condition or infection serotype. These results suggest that the association between high proinflammatory cytokine levels and dengue disease severity does not always stand, and it once again highlights the complex nature of DHF pathogenesis.
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Feminino , Humanos , Masculino , Citocinas/metabolismo , Vírus da Dengue/imunologia , Dengue Grave/imunologia , Vírus da Dengue/classificação , Dengue/imunologia , Ensaio de Imunoadsorção Enzimática , Mediadores da Inflamação/metabolismo , Interferon gama/sangue , /sangue , /sangue , /sangue , México , Reação em Cadeia da Polimerase em Tempo Real/métodos , Sorogrupo , Estatísticas não Paramétricas , Dengue Grave/sangue , Fator de Necrose Tumoral alfa/sangueRESUMO
BACKGROUND: Type 1 interferon (IFNα/ß) has a significant role in establishing protection against virus infections. It has been well documented by in vitro studies that dengue virus (DENV) activates a robust IFNα/ß response. However, DENV also induces a down-regulation of the JAK/STAT pathway, inhibiting the induction of interferon regulated genes. As a consequence, the role played by the IFN type 1 response in the protection of dengue patients is not fully understood. OBJECTIVE: To compare IFN-α levels in dengue patients with dengue fever (DF) or dengue hemorrhagic fever (DHF) undergoing primary or secondary infections. STUDY DESIGN: Two hundred and four serum samples were analyzed for IFN-α level by cytometric bead array. Patients' clinical condition was assigned following the WHO 1997 criteria and specific IgG and IgM antibodies were measured using commercial assays to determine primary and secondary infections. The infecting serotype was determined by qRT-PCR. RESULTS AND CONCLUSION: The IFN-α levels were found significantly higher in DF than DHF patients irrespective of the infecting serotype (DENV1 or 2), and were found to decline rapidly at day 3 after fever onset. For DENV2 infections, higher IFN-α level was found during primary than secondary infections. These results suggest that an early strong interferon response correlates with a better clinical condition.
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Vírus da Dengue , Dengue/sangue , Dengue/diagnóstico , Interferons/sangue , Anticorpos Antivirais/sangue , Anticorpos Antivirais/imunologia , Estudos de Casos e Controles , Dengue/imunologia , Vírus da Dengue/genética , Vírus da Dengue/imunologia , Genótipo , Humanos , Interferon-alfa/sangue , Dengue Grave/sangue , Dengue Grave/diagnóstico , Dengue Grave/imunologia , Índice de Gravidade de Doença , Fatores de TempoRESUMO
Transit of human neural stem cells, ReNcell CX, through the blood brain barrier (BBB) was evaluated in an in vitro model of BBB and in nude mice. The BBB model was based on rat brain microvascular endothelial cells (RBMECs) cultured on Millicell inserts bathed from the basolateral side with conditioned media (CM) from astrocytes or glioma C6 cells. Glioma C6 CM induced a significant transendothelial migration of ReNcells CX in comparison to astrocyte CM. The presence in glioma C6 CM of high amounts of HGF, VEGF, zonulin and PGE2, together with the low abundance of EGF, promoted ReNcells CX transmigration. In contrast cytokines IFN-α, TNF-α, IL-12p70, IL-1ß, IL-6, IL-8 and IL-10, as well as metalloproteinases -2 and -9 were present in equal amounts in glioma C6 and astrocyte CMs. ReNcells expressed the tight junction proteins occludin and claudins 1, 3 and 4, and the cell adhesion molecule CRTAM, while RBMECs expressed occludin, claudins 1 and 5 and CRTAM. Competing CRTAM mediated adhesion with soluble CRTAM, inhibited ReNcells CX transmigration, and at the sites of transmigration, the expression of occludin and claudin-5 diminished in RBMECs. In nude mice we found that ReNcells CX injected into systemic circulation passed the BBB and reached intracranial gliomas, which overexpressed HGF, VEGF and zonulin/prehaptoglobin 2.
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Barreira Hematoencefálica/citologia , Glioma/patologia , Células-Tronco Neurais/citologia , Migração Transendotelial e Transepitelial , Animais , Astrócitos/citologia , Astrócitos/efeitos dos fármacos , Astrócitos/metabolismo , Barreira Hematoencefálica/efeitos dos fármacos , Barreira Hematoencefálica/metabolismo , Linhagem Celular Tumoral , Toxina da Cólera/farmacologia , Claudinas/metabolismo , Meios de Cultivo Condicionados/metabolismo , Dinoprostona/farmacologia , Fenômenos Eletrofisiológicos/efeitos dos fármacos , Células Endoteliais/citologia , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/metabolismo , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Haptoglobinas , Fator de Crescimento de Hepatócito/farmacologia , Humanos , Imunoglobulinas/metabolismo , Metaloproteinase 2 da Matriz/metabolismo , Metaloproteinase 9 da Matriz/metabolismo , Camundongos , Células-Tronco Neurais/efeitos dos fármacos , Células-Tronco Neurais/metabolismo , Ocludina/metabolismo , Precursores de Proteínas , Ratos , Junções Íntimas/efeitos dos fármacos , Junções Íntimas/metabolismo , Migração Transendotelial e Transepitelial/efeitos dos fármacos , Fator A de Crescimento do Endotélio Vascular/farmacologiaRESUMO
Several cellular molecules and components, specifically, cholesterol and lipid rafts have been described as necessary elements for dengue virus entry and signaling in several human cells. Thus, changes in lipid rafts formation and cholesterol levels were evaluated. Here we report that the amount of total cholesterol and lipid rafts formation increase early after infection of Huh-7 cells. This augment correlates with an increase in the amount of low density lipoprotein receptor (LDLr) on the surface of infected cells and also with a lower phosphorylation level of the 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR). None of the changes were observed in Huh 7 cells infected with VSV used as a control. These results suggest that dengue virus infection increases intracellular cholesterol levels at early times post infection by triggering the modulation of LDL particles uptake and the increase in the enzymatic activity of HMG-CoA reductase.
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LDL-Colesterol/metabolismo , Vírus da Dengue/fisiologia , Interações Hospedeiro-Patógeno , Hidroximetilglutaril-CoA Redutases/metabolismo , Microdomínios da Membrana/metabolismo , Replicação Viral , Linhagem Celular , Hepatócitos/química , Hepatócitos/virologia , HumanosRESUMO
Severe dengue (SD) is a life-threatening complication of dengue that includes vascular permeability syndrome (VPS) and respiratory distress. Secondary infections are considered a risk factor for developing SD, presumably through a mechanism called antibody-dependent enhancement (ADE). Despite extensive studies, the molecular bases of how ADE contributes to SD and VPS are largely unknown. This work compares the cytokine responses of differentiated U937 human monocytic cells infected directly with dengue virus (DENV) or in the presence of enhancing concentrations of a humanized monoclonal antibody recognizing protein E (ADE-DENV infection). Using a cytometric bead assay, ADE-DENV-infected cells were found to produce significantly higher levels of the proinflammatory cytokines interleukin 6 (IL-6), IL-12p70, and tumor necrosis factor alpha (TNF-α), as well as prostaglandin E2 (PGE2), than cells directly infected. The capacity of conditioned supernatants (conditioned medium [CM]) to disrupt tight junctions (TJs) in MDCK cell cultures was evaluated. Exposure of MDCK cell monolayers to CM collected from ADE-DENV-infected cells (ADE-CM) but not from cells infected directly led to a rapid loss of transepithelial electrical resistance (TER) and to delocalization and degradation of apical-junction complex proteins. Depletion of either TNF-α, IL-6, or IL-12p70 from CM from ADE-DENV-infected cells fully reverted the disrupting effect on TJs. Remarkably, mice injected intraperitoneally with ADE-CM showed increased vascular permeability in sera and lungs, as indicated by an Evans blue quantification assay. These results indicate that the cytokine response of U937-derived macrophages to ADE-DENV infection shows an increased capacity to disturb TJs, while results obtained with the mouse model suggest that such a response may be related to the vascular plasma leakage characteristic of SD.
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Anticorpos Facilitadores/imunologia , Permeabilidade Capilar/imunologia , Citocinas/imunologia , Vírus da Dengue/imunologia , Dengue/fisiopatologia , Macrófagos/virologia , Análise de Variância , Animais , Western Blotting , Permeabilidade Capilar/efeitos dos fármacos , Sobrevivência Celular/fisiologia , Meios de Cultivo Condicionados/química , Meios de Cultivo Condicionados/farmacologia , Citocinas/metabolismo , Dengue/imunologia , Cães , Impedância Elétrica , Azul Evans , Imunofluorescência , Humanos , Macrófagos/metabolismo , Macrófagos/ultraestrutura , Células Madin Darby de Rim Canino , Camundongos , Microscopia Eletrônica de Transmissão , Junções Íntimas/metabolismo , Células U937RESUMO
Dengue is the most important mosquito-borne viral infection in humans. Recent evidence suggests that vitamin D influences virus replication. In this work, the effect of vitamin D treatment on dengue virus infection in human hepatic Huh-7 cells and on virus infection and cytokine production in the human monocytic U937 cells was evaluated. Exposure to 1α,25-dihydroxy-vitamin D3, resulted in a significant reduction in the number of infected cells, in conditions where cell viability was not affected. Viral replication in monocytic cells was more susceptible to vitamin D3 than replication in the hepatic cells. Moreover, vitamin D3 significantly reduced the levels of proinflammatory cytokines (TNF-α, IL-6, IL-12p70 and IL-1ß) produced by infected U937 cells. These results suggest that vitamin D3 may represent a potentially useful antiviral compound.
Assuntos
Citocinas/biossíntese , Vírus da Dengue/efeitos dos fármacos , Dengue/virologia , Regulação para Baixo/efeitos dos fármacos , Monócitos/imunologia , Vitamina D/análogos & derivados , Linhagem Celular , Citocinas/imunologia , Dengue/tratamento farmacológico , Dengue/imunologia , Vírus da Dengue/fisiologia , Humanos , Monócitos/efeitos dos fármacos , Monócitos/virologia , Células U937 , Replicação Viral/efeitos dos fármacos , Vitamina D/farmacologiaRESUMO
Dengue virus (DENV) is the causative agent of dengue fever and the more severe forms of the infection known as dengue haemorrhagic fever and dengue shock syndrome (DHF/DSS). Secondary infections with a serotype different from the primary infection are considered a risk factor for the development of DHF/DSS. One explanation for the increased risk of DHF/DSS development after heterologous secondary infections is the antibody-dependent enhancement (ADE) hypothesis. This hypothesis postulates that pre-existing non-neutralizing antibodies will form immune complexes with the new serotype-infecting virus that in turn will have enhanced capacity to infect macrophages and other Fcgamma receptor (FcgammaR)-bearing cells. Despite the evidence supporting the ADE hypothesis, the molecular mechanisms of ADE are not fully understood. In this work, we present evidence which indicates that intact lipid rafts are required for the ADE infection of U937 cells with DENV. Flow cytometry analysis to measure the percentage of infected cells showed that treatment of differentiated U937 cells with nystatin (30 microg ml(-1)), filipin (10 microg ml(-1)) or beta-methyl cyclodextrin (30 mM) significantly reduces (P<0.05) the ADE of DENV-4 infection in vitro without any effect on viability or the number of FcgammaR-bearing cells. Later cholesterol replenishment by supplementing treated cell cultures with bovine fetal serum for 24 h re-established lipid raft integrity and reversed the alteration of the ADE in vitro (P<0.05). Our results suggest that ADE of U937 infection by DENV requires the presence of cholesterol and cholesterol-rich membrane microdomains.