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Parasites & Vectors Jun 2024RNA interference (RNAi) is a target-specific gene silencing method that can be used to determine gene functions and investigate host-pathogen interactions, as well as...
BACKGROUND
RNA interference (RNAi) is a target-specific gene silencing method that can be used to determine gene functions and investigate host-pathogen interactions, as well as facilitating the development of ecofriendly pesticides. Commercially available transfection reagents (TRs) can improve the efficacy of RNAi. However, we currently lack a product and protocol for the transfection of insect cell lines with long double-stranded RNA (dsRNA).
METHODS
We used agarose gel electrophoresis to determine the capacity of eight TRs to form complexes with long dsRNA. A CellTiter-Glo assay was then used to assess the cytotoxicity of the resulting lipoplexes. We also measured the cellular uptake of dsRNA by fluorescence microscopy using the fluorophore Cy3 as a label. Finally, we analyzed the TRs based on their transfection efficacy and compared the RNAi responses of Aedes albopictus C6/36 and U4.4 cells by knocking down an mCherry reporter Semliki Forest virus in both cell lines.
RESULTS
The TRs from Biontex (K4, Metafectene Pro, and Metafectene SI+) showed the best complexing capacity and the lowest dsRNA:TR ratio needed for complete complex formation. Only HiPerFect was unable to complex the dsRNA completely, even at a ratio of 1:9. Most of the complexes containing mCherry-dsRNA were nontoxic at 2 ng/µL, but Lipofectamine 2000 was toxic at 1 ng/µL in U4.4 cells and at 2 ng/µL in C6/36 cells. The transfection of U4.4 cells with mCherry-dsRNA/TR complexes achieved significant knockdown of the virus reporter. Comparison of the RNAi response in C6/36 and U4.4 cells suggested that C6/36 cells lack the antiviral RNAi response because there was no significant knockdown of the virus reporter in any of the treatments.
CONCLUSIONS
C6/36 cells have an impaired RNAi response as previously reported. This investigation provides valuable information for future RNAi experiments by showing how to mitigate the adverse effects attributed to TRs. This will facilitate the judicious selection of TRs and transfection conditions conducive to RNAi research in mosquitoes.
Topics: RNA, Double-Stranded; Animals; Cell Line; RNA Interference; Transfection; Aedes; Gene Silencing; Semliki forest virus
PubMed: 38863029
DOI: 10.1186/s13071-024-06340-3 -
Parasites & Vectors Jun 2024Aedes aegypti is the primary mosquito vector for several arboviruses, such as dengue, chikungunya and Zika viruses, which cause frequent outbreaks of human disease in...
BACKGROUND
Aedes aegypti is the primary mosquito vector for several arboviruses, such as dengue, chikungunya and Zika viruses, which cause frequent outbreaks of human disease in tropical and subtropical regions. Control of these outbreaks relies on vector control, commonly in the form of insecticide sprays that target adult female mosquitoes. However, the spatial coverage and frequency of sprays needed to optimize effectiveness are unclear. In this study, we characterize the effect of ultra-low-volume (ULV) indoor spraying of pyrethroid insecticides on Ae. aegypti abundance within households. We also evaluate the effects of spray events during recent time periods or in neighboring households. Improved understanding of the duration and distance of the impact of a spray intervention on Ae. aegypti populations can inform vector control interventions, in addition to modeling efforts that contrast vector control strategies.
METHODS
This project analyzes data from two large-scale experiments that involved six cycles of indoor pyrethroid spray applications in 2 years in the Amazonian city of Iquitos, Peru. We developed spatial multi-level models to disentangle the reduction in Ae. aegypti abundance that resulted from (i) recent ULV treatment within households and (ii) ULV treatment of adjacent or nearby households. We compared fits of models across a range of candidate weighting schemes for the spray effect, based on different temporal and spatial decay functions to understand lagged ULV effects.
RESULTS
Our results suggested that the reduction of Ae. aegypti in a household was mainly due to spray events occurring within the same household, with no additional effect of sprays that occurred in neighboring households. Effectiveness of a spray intervention should be measured based on time since the most recent spray event, as we found no cumulative effect of sequential sprays. Based on our model, we estimated the spray effect is reduced by 50% approximately 28 days after the spray event.
CONCLUSIONS
The reduction of Ae. aegypti in a household was mainly determined by the number of days since the last spray intervention in that same household, highlighting the importance of spray coverage in high-risk areas with a spray frequency determined by local viral transmission dynamics.
Topics: Animals; Aedes; Insecticides; Mosquito Control; Mosquito Vectors; Pyrethrins; Spatio-Temporal Analysis; Family Characteristics; Female; Peru; Humans; Population Density; Dengue
PubMed: 38863023
DOI: 10.1186/s13071-024-06308-3 -
BMC Public Health Jun 2024Dengue causes approximately 10.000 deaths and 100 million symptomatic infections annually worldwide, making it a significant public health concern. To address this,...
Dengue causes approximately 10.000 deaths and 100 million symptomatic infections annually worldwide, making it a significant public health concern. To address this, artificial intelligence tools like machine learning can play a crucial role in developing more effective strategies for control, diagnosis, and treatment. This study identifies relevant variables for the screening of dengue cases through machine learning models and evaluates the accuracy of the models. Data from reported dengue cases in the states of Rio de Janeiro and Minas Gerais for the years 2016 and 2019 were obtained through the National Notifiable Diseases Surveillance System (SINAN). The mutual information technique was used to assess which variables were most related to laboratory-confirmed dengue cases. Next, a random selection of 10,000 confirmed cases and 10,000 discarded cases was performed, and the dataset was divided into training (70%) and testing (30%). Machine learning models were then tested to classify the cases. It was found that the logistic regression model with 10 variables (gender, age, fever, myalgia, headache, vomiting, nausea, back pain, rash, retro-orbital pain) and the Decision Tree and Multilayer Perceptron (MLP) models achieved the best results in decision metrics, with an accuracy of 98%. Therefore, a tree-based model would be suitable for building an application and implementing it on smartphones. This resource would be available to healthcare professionals such as doctors and nurses.
Topics: Machine Learning; Dengue; Mass Screening; Brazil; Decision Trees; Humans
PubMed: 38862945
DOI: 10.1186/s12889-024-19083-8 -
Scientific Reports Jun 2024Aedes aegypti is vector of many arboviruses including Zika, dengue, yellow fever, West Nile, and Chikungunya. Its control efforts are hampered by widespread insecticide...
Aedes aegypti is vector of many arboviruses including Zika, dengue, yellow fever, West Nile, and Chikungunya. Its control efforts are hampered by widespread insecticide resistance reported in the Americas and Asia, while data from Africa is more limited. Here we use publicly available 729 Ae. aegypti whole-genome sequencing samples from 15 countries, including nine in Africa, to investigate the genetic diversity in four insecticide resistance linked genes: ace-1, GSTe2, rdl and vgsc. Apart from vgsc, the other genes have been less investigated in Ae. aegypti, and almost no genetic diversity information is available. Among the four genes, we identified 1,829 genetic variants including 474 non-synonymous substitutions, some of which have been previously documented, as well as putative copy number variations in GSTe2 and vgsc. Global insecticide resistance phenotypic data demonstrated variable resistance in geographic areas with resistant genotypes. Overall, our work provides the first global catalogue and geographic distribution of known and new amino-acid mutations and duplications that can be used to guide the identification of resistance drivers in Ae. aegypti and thereby support monitoring efforts and strategies for vector control.
Topics: Insecticide Resistance; Animals; Aedes; Genetic Variation; Genomics; Mosquito Vectors; Insecticides; Insect Proteins; Whole Genome Sequencing; DNA Copy Number Variations
PubMed: 38862628
DOI: 10.1038/s41598-024-64007-6 -
Journal of Arthropod-borne Diseases Sep 2023flies are smooth, low upkeep and safe model organisms, they can be effortlessly used in different fields of life sciences like genomics, biotechnology, genetics,...
BACKGROUND
flies are smooth, low upkeep and safe model organisms, they can be effortlessly used in different fields of life sciences like genomics, biotechnology, genetics, disease model, and -based approaches to fight vectors and the pathogens they transmit.
METHODS
Fruit fly specimens were collected in 25 districts (14 provinces) of Iran and their morphological recognition was proven by molecular analysis based on sequence homology of mitochondrial COI barcode region. Essential information and specific requirements ere provided for laboratory rearing of .
RESULTS
colonies were found in 23 out of 25 districts. Also, five related species coincident with were reported in this study including , , (Diptera: Drosophilidae), and (Diptera: Phoridae). The Iranian molecular signature and their rearing techniques have been described here. The complete life cycle, from (egg to adult), takes approximately 8 days at 25 °C. Some biological points have been presented with highlighting capturing, rearing, culturing, and embryo collection along with primitive recognition and segregation between females and males have been presented. A recipe for culture media and the quantity of various ingredients have been provided.
CONCLUSION
This is the first report on the and species for the country. Results of this study provide efficient and effective rearing procedures which are requirement for both small-scale for facilitating entomological research and large-scale use in justifiable vector control management such as disease model or Dengue control.
PubMed: 38860195
DOI: 10.18502/jad.v17i3.14983 -
Infection Prevention in Practice Sep 2024Gastroenteritis accounts for about 10% of the deaths among children, especially in immunocompromised children. Few studies on the prevalence of gastrointestinal...
BACKGROUND
Gastroenteritis accounts for about 10% of the deaths among children, especially in immunocompromised children. Few studies on the prevalence of gastrointestinal infections caused by RNA viruses have been done in Iran. The aim of the study was to evaluate the detection of RNA viruses causing diarrhoea using a multiplex PCR.
METHODS
Stool samples were collected from 130 paediatric patients with diarrhoea who had acute lymphocytic leukaemia, non-Hodgkin lymphoma, and retinoblastoma. After RNA extraction and synthesis of cDNA, multiplex PCR was done to evaluate the presence of rotavirus, norovirus, astrovirus, and enterovirus.
RESULTS
There were 9 (6.9%), 7 (5.4%), 3 (2.3%), and 6 (4.6%) cases of rotavirus, norovirus, astrovirus, and enterovirus detected, respectively. One case of co-infection with astrovirus and norovirus was observed.
CONCLUSIONS
This is the first report from Iran which identified the presence of common RNA viruses causing diarrhoea in immunocompromised children. Increased awareness of these viruses will enable healthcare professionals to improve strategies and policies to control spread and infection caused by these viruses.
PubMed: 38855735
DOI: 10.1016/j.infpip.2024.100370 -
BioRxiv : the Preprint Server For... Jun 2024Survival through periods of drought is critical for mosquitoes to reside in semi-arid regions with humans, but water sources may be limited. Previous studies have shown...
Survival through periods of drought is critical for mosquitoes to reside in semi-arid regions with humans, but water sources may be limited. Previous studies have shown that dehydrated mosquitoes will increase blood feeding propensity, but how this would occur over extended dry periods is unknown. Following a bloodmeal, prolonged exposure to dry conditions increased secondary blood feeding in mosquitoes by nearly two-fold, and chronic blood feeding allowed mosquitoes to survive twenty days without access to water sources. This refeeding did not alter the number of eggs generated, suggesting this refeeding is for hydration and nutrient replenishment. Exposure to desiccating conditions following a bloodmeal resulted in increased activity, decreased sleep levels, and prompted a return of CO2 sensing before egg deposition. The increased blood feeding during the vitellogenic stage and higher survival during dry periods are predicted to increase pathogen transmission and explain the elevated levels of specific arbovirus cases during dry conditions. These results solidify our understanding of the role of dry periods on mosquito blood feeding and how mosquito dehydration contributes to vectorial capacity and disease transmission dynamics.
PubMed: 38854138
DOI: 10.1101/2024.05.28.595907 -
The Journal of Biological Chemistry Jun 2024Identification of a conserved G-quadruplex in E165R of ASFVAfrican swine fever virus (ASFV) is a double-stranded DNA arbovirus with high transmissibility and mortality...
Identification of a conserved G-quadruplex in E165R of ASFVAfrican swine fever virus (ASFV) is a double-stranded DNA arbovirus with high transmissibility and mortality rates. It has caused immense economic losses to the global pig industry. Currently, no effective vaccines or medications are to combat ASFV infection. G-quadruplex (G4) structures have attracted increasing interest because of their regulatory role in vital biological processes. In this study, we identified a conserved G-rich sequence within the E165R gene of ASFV. Subsequently, using various methods, we verified that this sequence could fold into a parallel G4. In addition, the G4-stabilizers pyridostatin and 5,10,15,20-tetrakis-(N-methyl-4-pyridyl) porphin (TMPyP4) can bind and stabilize this G4 structure, thereby inhibiting E165R gene expression, and the inhibitory effect is associated with G4 formation. Moreover, the G4 ligand pyridostatin substantially impeded ASFV proliferation in Vero cells by reducing gene copy number and viral protein expression. These compelling findings suggest that G4 structures may represent a promising and novel antiviral target against ASFV.
PubMed: 38852886
DOI: 10.1016/j.jbc.2024.107453 -
Lancet Regional Health. Americas Jul 2024This study focuses on urban arboviruses, specifically dengue (DENV), chikungunya (CHIKV), and Zika (ZIKV), which pose a significant public health challenge in Rio de...
BACKGROUND
This study focuses on urban arboviruses, specifically dengue (DENV), chikungunya (CHIKV), and Zika (ZIKV), which pose a significant public health challenge in Rio de Janeiro state, Southeast Brazil. In our research, we highlight critical findings on the transmission dynamics of these arboviruses in Rio de Janeiro, identifying distinct patterns of disease spread.
METHODS
By combining genomic data with case reports from the Brazilian Ministry of Health, we have analysed the phylogenetics, prevalence and spatial distribution of these endemic viruses within the state.
FINDINGS
Our results revealed sustained DENV transmission primarily in the northern part of the state, a significant ZIKV epidemic in 2016 affecting all mesoregions, and two major CHIKV outbreaks in 2018 and 2019, predominantly impacting the northern and southern areas. Our analysis suggests an inverse relationship between arboviral case incidence and urban density, with less populous regions experiencing higher transmission rates, potentially attributed to a complex interplay of factors such as the efficacy of vector control measures, environmental conditions, local immunity levels, and human mobility. Furthermore, our investigation unveiled distinct age and gender trends among affected individuals. Notably, dengue cases were predominantly observed in young adults aged 32, while chikungunya cases were more prevalent among individuals over 41. In contrast, cases of ZIKV were concentrated around the 33-year age group. Intriguingly, females accounted for nearly 60% of the cases, suggesting a potential gender-based difference in infection rates.
INTERPRETATION
Our findings underscore the complexity of arbovirus transmission and the need for interventions tailored to different geographical mesoregions. Enhanced surveillance and genomic sequencing will be essential for a deeper, more nuanced understanding of regional arbovirus dynamics. Identifying potential blind spots within the state will be pivotal for developing and implementing more effective public health strategies, specifically designed to address the unique challenges posed by these viruses throughout the state.
FUNDING
This study was supported by the National Institutes of Health USA grant U01 AI151698 for the United World Arbovirus Research Network (UWARN) and the CRP-ICGEB RESEARCH GRANT 2020 Project CRP/BRA20-03.
PubMed: 38846808
DOI: 10.1016/j.lana.2024.100786 -
Current Opinion in Infectious Diseases Aug 2024Arbovirus infections are a challenge for immunocompromised hosts who travel to or live in endemic regions or who receive organs or tissues from donors who travel or live... (Review)
Review
PURPOSE OF REVIEW
Arbovirus infections are a challenge for immunocompromised hosts who travel to or live in endemic regions or who receive organs or tissues from donors who travel or live in such areas. This review addresses Dengue (DENV), Chikungunya (CHIKV), and Zika (ZIKV) infections in hematological patients, hematopoietic cell or solid organ transplant recipients, and people with HIV (PWH).
RECENT FINDINGS
Transmission is mainly due through Aedes mosquito bite. DENV and ZIKV may also be transmitted through blood, tissues or donor grafts. Clinical manifestations are quite similar and diagnosis requires laboratory confirmation to provide appropriate management. The best diagnostic method is PCR since serology may present false negative results in immunocompromised patients, or cross-reactivity as in the case of DENV and ZIKV. There is no specific treatment for any of these infections.
SUMMARY
Educational and preventive measures are the best strategy: vector control, knowledge of the vector's habits, protection against mosquito bites, avoiding travel to endemic areas or with a current epidemic, and avoiding nonvector transmission according to local recommendations for donor deferral. Vaccination, currently only available for DENV, has not yet been studied in immunocompromised patients and is not currently recommended.
Topics: Humans; Immunocompromised Host; Dengue; Chikungunya Fever; Zika Virus Infection; Endemic Diseases; Animals
PubMed: 38842472
DOI: 10.1097/QCO.0000000000001026