Insecticide resistance status and mechanisms in Aedes aegypti and Aedes albopictus from different dengue endemic regions of Panama.

BACKGROUND: Dengue is a serious public health problem worldwide, including Panama. During the last years, the number of dengue cases has increased. This may be due to the presence of mosquito populations resistant to insecticides. The aim of this study was to characterize the resistance status, its enzymatic mechanisms and Kdr mutations in wild populations of Aedes aegypti and Aedes albopictus. METHODS: Standard WHO bioassays were performed using insecticide-treated filter papers to determine resistance in populations Ae. aegypti and Ae. albopictus to pyrethroids insecticides, organophosphates, to the carbamate propoxur and to the organochlorine DDT. Biochemical assays were conducted to detect metabolic resistance mechanisms and real-time PCR was performed to determine the frequencies of the Kdr mutations Val1016IIe and F1534C. RESULTS: The strains Ae. aegypti El Coco showed confirmed resistance to deltamethrin (78.5% mortality) and lambda-cyhalothrin (81%), Aguadulce to deltamethrin (79.3%), David to deltamethrin (74.8%) and lambda-cyhalothrin (87.5%) and Puerto Armuelles to permethrin (83%). Aedes aegypti El Empalme showed confirmed resistance to pirimiphos-methyl (62.3% mortality), chlorpyrifos-methyl (55.5%) and propoxur (85.3%). All strains of Ae. albopictus showed possible resistance to PYs and five strains to DDT. Only Ae. albopictus Canto del Llano showed confirmed resistance to pirimiphos-methyl (70% mortality) and malathion (62%). Esterase activity was variable across sites with the most frequent expression of α-EST compared to ß-EST in Ae. aegypti populations. In Ae. Albopictus, the expressed enzymes were ß-EST and MFOs. Through ANOVA, significant differences were established in the levels of enzymatic activity of α- and ß-EST, MFOs and GST, with p < 0.001 in the Ae. aegypti and Ae. albopictus. The Kdr Val1016IIe mutation was detected in Ae. aegypti Aguadulce, El Coco and David. The odds ratio for the Val1016Ile mutation ranged from 0.8 to 20.8 in resistant mosquitoes, indicating the association between pyrethroid phenotypic resistance and the kdr mutation. CONCLUSION: The presence of a varied and generalized resistance, enzymatic mechanisms and the Val1016IIe mutation may be associated with the intensive use and possibly misuse of the different insecticides applied to control Aedes populations. These results highlight the need to develop a program for resistance management. Also, alternative approaches to mosquito control that do not involve insecticides should be explored.

Widespread geographic distribution of Aedes aegypti (Diptera: Culicidae) kdr variants in Panama.

We searched for evidence of knockdown resistance (kdr) mutations in the voltage-gated sodium channel gene of Aedes aegypti (Linnaeus) (Diptera: Culicidae) and Aedes albopictus (Skuse) (Diptera: Culicidae) mosquitoes from Panama. Conventional PCR was performed on 469 Ae. aegypti and 349 Ae. albopictus. We did not discover kdr mutations in Ae. albopictus, but 2 nonsynonymous kdr mutations, V1016I (found in 101 mosquitoes) and F1534C (found in 29 of the mosquitoes with the V1016I), were detected in Ae. aegypti. These kdr mutations were present in all specimens that were successfully sequenced for both IIS5-S6 and IIIS6 regions, which included samples collected from 8 of the 10 provinces of Panama. No other kdr mutations were found in Ae. aegypti, including V1016G, which has already been reported in Panama. Findings suggest that the V1016I-F1534C variant is prevalent in Panama, which might be related to the introduction and passive movement of mosquitoes as part of the used-tire trade. However, we cannot rule out the possibility that selection on de novo replacement of kdr mutations also partially explains the widespread distribution pattern of these mutations. These 2 ecological and evolutionary processes are not mutually exclusive, though, as they can occur in tandem. Research in Panama needs to calculate the genotypic and allelic frequencies of kdr alleles in local Ae. aegypti populations and to test whether some combinations confer phenotypic resistance or not. Finally, future studies will have to track the introduction and spreading of new kdr mutations in both Aedes species.

Measuring local genetic variation in permethrin-resistant head lice (Phthiraptera: Pediculidae) from Buenos Aires, Argentina.

The cosmopolitan ectoparasite human head louse, Pediculus humanus capitis (De Geer)(Phthiraptera:Pediculidae), affects mostly school-aged children, with infestations reported every year mainly due to louse resistance to pyrethroids. One of the main resistance mechanisms of pyrethroids is the target site insensitivity (kdr), which is caused by single-nucleotide point mutations (SNPs) located in the voltage-sensitive sodium channel gene. In this study, we analyzed individual head lice toxicologically via the description of their susceptibility profile to permethrin and genetically through the genotypification of their kdr alleles as well as nuclear microsatellite loci. Lice were collected from 4 schools in the city of Buenos Aires, Argentina. The resistance ratios varied from 33.3% to 71.4%, with a frequency of the T917I kdr mutation of 87.31% and with 83.6% of the head lice being homozygous resistant to pyrethroids. Microsatellite data indicated that all the louse school populations had genotype proportions that deviated from Hardy-Weinberg expectations, with FIS > 0 reflecting a deficit of heterozygotes. Bottleneck analysis suggested that all louse school populations underwent a recent reduction in population sizes, while 3 of the 4 schools had gene flow values around 1, indicating ongoing gene flow among those schools. Our study suggests that school louse populations in the city of Buenos Aires may form a metapopulation, where each school represents a small population that undergoes extinction and recolonization processes under strong permethrin selection. This is the first multilevel analysis integrating toxicological, kdr-genotyping, and microsatellite data in human louse populations.

Aedes aegypti Knockdown Resistance Mutations and Dengue Virus Infection in Haiti.

Haiti is home to approximately 11 million people and has a high incidence of vector-borne disease, including more than 70,000 cases of dengue per year. Vector control is difficult in Haiti and adulticide spray of malathion is the main method of control employed during the outbreak of disease although pyrethroids are used in both bed net campaigns and in widely available aerosol cans for personal use. However, limited pathogen or insecticide resistance surveillance data are available for making operational decisions. In this study, we assessed Aedes aegypti from serial surveillance collections from 3 locations for the presence of dengue virus serotypes 1-3 (DENV1-3) by polymerase chain reaction and assessed, by melt curve analysis, samples from 10 locations in 2 departments for the presence of two mutations (V1016I and F1534C), that in combination, are linked to strong pyrethroid insecticide resistance. Only one of the 32 tested pools was positive for the presence of dengue virus. The two knockdown resistance (kdr) mutations were present in all locations. The 1016I mutation frequency varied from 0.29 to 0.91 and was in all sites lower than the 0.58-1.00 frequency of the 1534C mutation. We also observed that the genotype homozygous for both mutations (IICC), which has been linked to strong pyrethroid resistance, varied from 13 to 86% in each population. Notably, 3 locations - Ti Cousin and Christianville in Ouest department and Camp Coq in Nord department had more than 30% of the tested population without the presence of kdr mutations. These results indicate that the kdr markers of pyrethroid resistance are present in Haiti, at high frequency in several locations and, based on previous studies linking kdr genotypes and phenotypic resistance, that operational interventions with pyrethroids are not likely to be as effective as expected.

Phenotypic resistance not associated with knockdown mutations (kdr) in Anopheles albimanus exposed to deltamethrin in southern coastal Ecuador.

BACKGROUND: Decrease in malaria rates (e.g. incidence and cases) in Latin America maintains this region on track to achieve the goal of elimination. During the last 5 years, three countries have been certified as malaria free. However, the region fails to achieve the goal of 40% reduction on malaria rates and an increase of cases has been reported in some countries, including Ecuador. This scenario has been associated with multiple causes, such as decrease of funding to continue anti-malarial programmes and the development of insecticide resistance of the main malaria vectors. In Ecuador, official reports indicated phenotypic resistance in Aedes aegypti and Anopheles albimanus to deltamethrin and malathion, particularly in the coastal areas of Ecuador, however, information about the mechanisms of resistance have not been yet elucidated. This study aims to evaluate phenotypic response to deltamethrin and its relationship with kdr mutations in An. albimanus from two localities with different agricultural activities in southern coastal Ecuador. METHODS: The CDC bottle assay was carried out to evaluate the phenotypic status of the mosquito's population. Sequencing the voltage gated sodium channel gene (VGSC) sought knockdown mutations (kdr) in codons 1010, 1013 and 1014 associated with resistance. RESULTS: Phenotypic resistance was found in Santa Rosa (63.3%) and suspected resistance in Huaquillas (82.1%); with females presenting a higher median of knockdown rate (83.7%) than males (45.6%). No statistical differences were found between the distributions of knockdown rate for the two localities (p = 0.6048) which indicates no influence of agricultural activity. Although phenotypic resistance was confirmed, genetic analysis demonstrate that this resistance was not related with the kdr mechanism of the VGSC gene because no mutations were found in codons 1010 and 1013, while in codon 1014, 90.6% showed the susceptible sequence (TTG) and 7.3% ambiguous nucleotides (TKK and TYG). CONCLUSIONS: These results highlighted the importance of continuous monitoring of resistance in malaria vectors in Ecuador, particularly in areas that have reported outbreaks during the last years. It is also important to elucidate the mechanism involved in the development of the resistance to PYs to propose alternative insecticides or strategies for vector control in areas where resistance is present.

PDGFRA, KIT, and KDR Gene Amplification in Glioblastoma: Heterogeneity and Clinical Significance.

Glioblastoma (GBM) is the most frequent tumor of the central nervous system, and its heterogeneity is a challenge in treatment. This study examined tumoral heterogeneity involving PDGFRA, KIT, and KDR gene amplification (GA) in 4q12 and its association with clinical parameters. Specimens from 22 GBM cases with GA for the 4q12 amplicon detected by FISH were investigated for homogeneous or heterogeneous coamplification patterns, diffuse or focal distribution of cells harboring GA throughout tumor sections, and pattern of clustering of fluorescence signals. Sixteen cases had homogenously amplification for all three genes (45.5%), for PDGFRA and KDR (22.7%), or only for PDGFRA (4.6%); six cases had heterogeneous GA patterns, with subpopulations including GA for all three genes and for two genes - PDGFRA and KDR (13.6%), or GA for all three and for only one gene - PDGFRA (9.1%) or KIT (4.6%). In 6 tumors (27.3%), GA was observed in focal tumor areas, while in the remaining 16 tumors (72.7%) it was diffusely distributed throughout the pathological specimen. Amplification was universally expressed as double minutes and homogenously stained regions. Coamplification of all three genes PDGFRA, KIT, and KDR, age ≥ 60 years, and total tumor resection were statistically associated with poor prognosis. FISH proved effective for detailed interpretation of molecular heterogeneity. The study uncovered an even more diverse range of amplification patterns involving the 4q12 oncogenes in GBM than previously described, thus highlighting a complex tumoral heterogeneity to be considered when devising more effective therapies.

Association of single nucleotide variants in VEGFA and KDR with the risk and angiogenic features of diffuse large B-cell lymphoma.

Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoma subtype and dependent on angiogenesis (AG), whose main effectors are VEGFA and VEGFR2. Functional single nucleotide variants (SNVs) are described in VEGFA and KDR genes. However, it still unknown whether VEGFA - 2578C/A, -2489C/T, -1154G/A, -634G/C, -460C/T and KDR-604T/C, -271G/A, +1192G/A and +1719A/T SNVs act on DLBCL risk and angiogenic features. Genomic DNA from 168 DLBCL patients and 205 controls was used for SNV genotyping. Angiogenesis was immunohistochemically assessed in tumor biopsies, with reactions for VEGFA, VEGFR2, and CD34. VEGFA -1154GG genotype were associated with 1.6-fold higher DLBCL risk. KDR + 1192GG plus KDR + 1719 TT and KDR + 1192GG plus VEGFA - 2578CC combined genotypes are associated with 2.19- and 2.04-fold higher risks of DLBCL, respectively. VEGFA - 634GG or GC genotypes are associated with increased microvessel density and VEGFA levels. No relationship was observed between SNVs and cell-of-origin classification of DLBCL, but higher VEGFA and VEGFR2 were seen in non-germinal center tumors.

Status of Acaricide Resistance and Detecting the Knockdown Resistance Mutation T2134A in the Cattle Tick Rhipicephalus microplus (Acari: Ixodidae) from Northeastern Mexico.

Rhipicephalus microplus is the most important tick in veterinary medicine, given its repercussions on animal production. The principal strategy to avoid adverse effects associated with R. microplus is the chemical control of tick populations through organosynthetic acaricides. Therefore, monitoring susceptibility to acaricides is paramount in any control program. This study aimed to analyze the resistance status of 2 populations of R. microplus from northeastern Mexico to the organochlorine (OC) lindane, organophosphates (OP) coumaphos, chlorfenvinphos, diazinon, and chlorpyrifos, and the synthetic pyrethroids (SPs) flumethrin, deltamethrin, and cypermethrin. Discriminating doses (DD) of each acaricide were used in the larval packet bioassay (LPT). Additionally, the presence of the knockdown resistance (kdr) mutation T2134A associated with pyrethroid resistance was evaluated using allele-specific polymerase chain reaction (PCR). The populations of R. microplus showed a high frequency of resistance to SP, with mortality rates of less than 5%; they also showed resistance to the OPs (diazinon and chlorpyrifos) with mortality rates ranging from 1.29% to 34.62%; meanwhile, they were susceptible to coumaphos and chlorfenvinphos. Mortality rates higher than 66% were observed for lindane, indicating susceptibility. The mutant allele of the kdr mutation T2134A was detected in 75% and 100% of the pools analyzed. The populations studied presented a highly resistant profile to pyrethroids, with the presence of the kdr mutant allele A2134. The susceptibility to the organophosphates such as coumaphos and chlorfenvinphos of R. microplus from northeastern Mexico should be noted.

Pyrethroid genetic resistance in the dengue vector (Aedes aegypti) in Posadas, Argentina.

Pyrethroids are extensively used to control adult populations of the arboviral vector Aedes aegypti, raising concerns regarding the increasing frequency and distribution of insecticide resistance mutations (kdr: knock-down resistance) in the voltage-gated sodium channel gene (Nav). The widespread use of pyrethroids imposes a threat to the success of mosquito control and the environment. In this study, we investigated the presence of two kdr mutations (V1016I and F1534C) in the Nav gene and their distribution across four neighborhoods in Posadas, Argentina, with different Ae. aegypti abundance and contrasting socioeconomic status (SES). Alleles at each locus were interrogated using TaqMan SNP genotyping assays in DNA extracted from adult females collected in a longitudinal study. We report the presence of both pyrethroid resistance alleles (kdr 1016I = 29.08%; kdr 1534C = 70.70%) among adult females. The frequency of combined kdr genotypes reveals that approximately 70% of local adult females have enhanced resistance to pyrethroids. Both, the proportion of resistant adult females (with at least one kdr allele in each locus) and Ae. aegypti abundance showed an uneven distribution between neighborhoods with different SES (p < 0.001). In high-SES neighborhoods, we found more mosquitoes and a higher frequency of pyrethroid resistance, possibly as a consequence of different public health interventions, social habits, and insecticide use. This is the first report of kdr mutations in Ae. Aegypti in the northeast region of Argentina. Our results focus on the need for within-population (city) distribution analyses of kdr mutations and highlight the relevance of incorporating insecticide resistance monitoring within the Integrated Vector Management initiative.

Global Pattern of kdr-Type Alleles in Musca domestica (L.).

Purpose of Review: Houseflies, Musca domestica L., are an important sanitary pest that affects human and domesticated animals. They are mechanical carriers of more than 100 human and animal diseases including protozoan, bacterial, helminthic, and viral infections. Recently, it was demonstrated that houseflies acquired, harbored, and transmitted SARS-CoV-2 (COVID-19) for up to 1 day post-exposure. The most widely used control strategy relays on the application of pyrethroid insecticides due to their effectiveness, low mammalian toxicity, low cost, and environmental safety. The main mechanism of action of pyrethroids is to exert their toxic effects through affecting the voltage-sensitive sodium channel (VSSC) modifying the transmission of the nerve impulse and leading to the death of the insects. Target site insensitivity of the VSSC is due to the presence of single nuclear polymorphisms (SNPs) named knockdown mutations (kdr). In this review, we synthetize recent data on the type and distribution of these mutations globally. Recent Findings: Housefly resistance is reported in several countries. Increased applications of pyrethroids to control housefly populations led to the emergence of multiple evolutionary origins of resistance determined by five amino acid substitutions or specific mutations in the VSSC: kdr (L1014F), kdr-his (L1014H), super-kdr (M918T + L1014F), type N (D600N + M918T + L1014F), and 1B (T929I + L1014F). According to the global map obtained, high levels of resistance to pyrethroids are associated with the L1014F mutation found mostly in North America, Europe, and Asia, while the super-kdr mutation was mostly found in the American continent. The level of protection conferred by these alleles against pyrethroids was generally kdr-his < kdr < Type N ≤ super-kdr ≤ 1B. The relative fitness of the alleles under laboratory conditions was susceptible ≅ kdr-his > kdr > super-kdr suggesting that the fitness cost of an allele was relative to the presence of other alleles in a population and that the reversion of resistance in a free insecticide environment might be quite variable from one region to another. Summary: An adequate integrated pest management program should consider monitoring susceptibility to pyrethroids to detect early levels of resistance and predict the spread and evolution of resistant phenotypes and genotypes. From this review, the pyrethroid resistance status of housefly population was determined in very few countries and has evolved independently in different areas of the world affecting chemical control programs.

Insecticide resistance levels and associated mechanisms in three Aedes aegypti populations from Venezuela

BACKGROUND The massive use of insecticides in public health has exerted selective pressure resulting in the development of resistance in Aedes aegypti to different insecticides in Venezuela. Between 2010 and 2020, the only insecticides available for vector control were the organophosphates (Ops) fenitrothion and temephos which were focally applied. OBJECTIVES To determine the state of insecticide resistance and to identify the possible biochemical and molecular mechanisms involved in three populations of Ae. aegypti from Venezuela. METHODS CDC bottle bioassays were conducted on Ae. aegypti collected between October 2019 and February 2020 in two hyperendemic localities for dengue in Aragua State and in a malaria endemic area in Bolívar State. Insecticide resistance mechanisms were studied using biochemical assays and polymerase chain reaction (PCR) to detect kdr mutations. FINDINGS Bioassays showed contrasting results among populations; Las Brisas was resistant to malathion, permethrin and deltamethrin, Urbanización 19 de Abril was resistant to permethrin and Nacupay to malathion. All populations showed significantly higher activity of mixed function oxidases and glutathione-S-transferases (GSTs) in comparison with the susceptible strain. The kdr mutations V410L, F1534C, and V1016I were detected in all populations, with F1534C at higher frequencies. MAIN CONCLUSION Insecticide resistance persists in three Ae. aegypti populations from Venezuela even in the relative absence of insecticide application.

Genetic diversity and Kdr mutations of natural Aedes (Stegomyia) aegypti (Diptera: Culicidae) populations of Brazil

ABSTRACT Aedes (Stegomyia) aegypti is an important vector of dengue, yellow fever, chikungunya and Zika virus. It is well known that resistance monitoring and genetic diversity data help designing the vector control programs. This study aimed to evaluate resistance to pyrethroids (PYs) through the frequency of kdr mutations Val1016IIe and F1534C, and the genetic variation of the mitochondrial gene ND4 in six natural populations of A. aegypti from Paraná - Brazil. Adults were obtained from eggs collected from Alvorada do Sul, Marilena, Maringá, Nova Londrina, Paranavaí and São Carlos do Ivaí. From these adults, 345 were used to identify the 1016 and 1534 sites, and 120 were used to perform the ND4 gene analysis. The studied populations from Paraná showed PYs resistance, low gene flow and genetic diversity. Additionally, a relationship was observed among the haplotypes of populations from the Amazon and Southeastern Brazil, Peru, Mexico, and North America.

The Association of Biochemical and Genetic Biomarkers in VEGF Pathway with Depression.

VEGF is an important neurotrophic and vascular factor involved in mental disorders. The objective of this study was to verify the effect of genetic polymorphisms in the VEGF pathway on the risk for depression, symptom intensity, and suicide attempts. To examine the association between the VEGF pathway and depression, we genotyped polymorphisms and measured the plasma concentrations of VEGF, KDR, and FLT1 proteins. The participants were 160 patients with depression and 114 healthy controls. The questionnaires that assessed the clinical profile of the patients were the MINI-International Neuropsychiatric Interview, GRID-HAMD21, CTQ, BSI, and the number of suicide attempts. Genotyping of participants was performed using the real-time PCR and protein measurements were performed using the enzyme-linked immunosorbent assay (ELISA). VEGF and its inhibitors were reduced in depression. Individuals with depression and displaying the homozygous AA of the rs699947 polymorphism had higher plasma concentrations of VEGF (p-value = 0.006) and were associated with a greater number of suicide attempts (p-value = 0.041). Individuals with depression that were homozygous for the G allele of the FLT1 polymorphism rs7993418 were associated with lower symptom severity (p-value = 0.040). Our results suggest that VEGF pathway polymorphisms are associated with the number of suicide attempts and the severity of depressive symptoms.

Determination of Knockdown Resistance (kdr) Allele Frequencies (T929I mutation) in Head Louse Populations from Mexico, Canada, and Peru.

The head louse Pediculus humanus capitis (De Geer) is a hematophagous ectoparasite that inhabits the human scalp. The infestations are asymptomatic; however, skin irritation from scratching occasionally may cause secondary bacterial infections. The present study determined the presence and frequency of the knockdown resistance (kdr) mutation T929I in 245 head lice collected from Mexico, Peru, and Canada. Head lice were collected manually using a comb in the private head lice control clinic. Allele mutation at T9291 was present in 100% of the total sampled populations (245 lice) examined. In addition, 4.89% of the lice were homozygous susceptible, whereas 6.93% heterozygous and 88.16% homozygous were resistant, respectively. This represents the second report in Mexico and Quebec and fist in Lima.

Spatial Distribution of Pyrethroid Resistance and kdr Mutations in Aedes aegypti from La Guajira, Colombia.

Dengue, chikungunya, and Zika are of great concern to the public health of Colombia. One of the main control strategies for these diseases is the application of insecticides directed at the Aedes aegypti vector. However, insecticide resistance has been increasingly recorded in the country, making control measures difficult. Here, we evaluated the resistance profiles for pyrethroids in populations of Ae. aegypti from La Guajira, Colombia. The frequency (diagnostic dose, DD) and intensity (2×, 5×, and 10× DD) of resistance to permethrin, deltamethrin, and lambda-cyhalothrin were determined in 15 populations of Ae. aegypti from La Guajira, Colombia, using the bottle bioassay. The kdr mutations V1016I, F1534C, and V410L, were identified, and their allele and genotype frequencies were calculated. Finally, the mortality values for the analyzed pyrethroids were interpolated following the IDW method for predicting pyrethroid resistance. The populations of Ae. aegypti showed a high frequency of resistance to permethrin with a low to moderate intensity, which was associated with the triple-resistant haplotype LL410/II1016/CC1534. They remain susceptible to deltamethrin and, in some populations, expressed the risk of developing resistance to lambda-cyhalothrin.

Estudo de associação entre polimorfismos genéticos e níveis plasmáticos do VEGF, FLT1, KDR e o risco para depressão / Study of association between genetic polymorphisms and plasma levels of VEGF, FLT1, KDR and the risk for depression

Introdução: a depressão é um transtorno mental comum, grave e incapacitante que afeta mais de 350 milhões de pessoas em todo o mundo. A depressão é caracterizada principalmente por sintomas como tristeza, perda de interesse, diminuição da energia, perda de confiança e autoestima, culpa inadequada, distúrbios do sono e do apetite, pensamentos de morte e suicídio. Além disso, essa patologia também tem um forte impacto na qualidade de vida dos indivíduos afetados e de suas famílias. Sabe-se que fatores genéticos interagem com as condições socioambientais de modo a influenciar a predisposição das pessoas ao adoecimento. Estudos identificaram polimorfismos de nucleotídeos simples (SNPs) que podem ser marcadores genéticos apropriados para prever inflamação sistêmica, por exemplo, e a atual tese teve como foco o efeito de SNPs na via do fator de crescimento endotelial vascular (VEGF). Esta proteína é uma potente molécula angiogênica e está envolvida na neurogênese do hipocampo, uma das principais estruturas límbicas afetadas em pessoas com depressão. O VEGF está implicado em uma das principais teorias que tentam explicar a fisiopatologia deste transtorno mental grave, a teoria neurotrófica, a qual diz que a diminuição ou desregulação da sinalização de neurotrofinas pode contribuir para a manifestação do transtorno depressivo (TD). Objetivo: avaliar se polimorfismos do VEGF e seus receptores, KDR e FLT1, estão associados à depressão e à gravidade dos sintomas, à ideação e tentativas de suicídio, independentemente tanto de um tratamento otimizado quanto da presença de estresse precoce (do inglês, early-life stress, ELS), também verificar se há efeito destes polimorfismos nas concentrações plasmáticas de proteínas expressas pelos seus respectivos genes e observar se existe correlação entre VEGF e seus inibidores, VEGF e s100ß. Metodologia: participaram do presente estudo 160 pacientes com depressão e 114 controles saudáveis. Foram aplicados durante entrevista questionários que avaliaram o perfil clínico dos pacientes como o MINI-International Neuropsychiatric Interview, GRID-HAMD21, CTQ, BSI e foi registrado o número de tentativas de suicídio. Os controles passaram por uma entrevista para serem avaliados quanto aos critérios de inclusão e exclusão do grupo. A genotipagem dos participantes foi realizada através da técnica de Real Time PCR e as mensurações de proteínas por meio do ensaio ensaio imunoenzimático (ELISA). Resultados: indivíduos com depressão, homozigotos AA do polimorfismo rs699947, apresentaram maiores concentrações plasmáticas de VEGF (P-valor= 0.006) e se associaram a um maior número de tentativas de suicídio na análise direta (P-valor= 0.041) e na análise corrigida foi observada uma tendência para a confirmação deste resultado (P-valor= 0.076). O genótipo homozigoto GG do polimorfismo rs7993418 do FLT1 se associou à severidade de sintomas (P-valor= 0.040), bem como uma tendência de associação com um aumento nas tentativas de suicídio e uma maior pontuação na escala que avaliou ideação suicida. Entre os pacientes quanto maior foram as concentrações plasmáticas de VEGF, maior foram as de KDR, FLT1 e s100ß. Conclusão: os resultados sugerem que os polimorfismos da via VEGF estão associados ao número de tentativas de suicídio e severidade dos sintomas depressivos.

Introduction: Depression is a common, serious, and disabling mental disorder that affects more than 350 million people worldwide. Depression is mainly characterized by symptoms such as sadness, loss of interest, decreased energy, loss of confidence and self-esteem, inadequate guilt, sleep and appetite disturbances, thoughts of death and suicide. Furthermore, this pathology also has a strong impact on the quality of life of those affected and their families. It is known that genetic factors interact with social and environmental conditions to influence people's predisposition to illness. Studies have identified single nucleotide polymorphisms (SNPs) that may be appropriate genetic markers to predict systemic inflammation, for example, and the current thesis focused on the effect of SNPs on the vascular endothelial growth factor (VEGF) pathway. This protein is a potent angiogenic molecule and is involved in hippocampal neurogenesis, one of the main limbic structures affected in people with depression. VEGF is implicated in one of the main theories that try to explain the pathophysiology of this severe mental disorder, the neurotrophic theory, which says that the decrease or dysregulation of neurotrophin signaling can contribute to the manifestation of depressive disorder (DT). Objective: to assess whether polymorphisms of VEGF and its receptors, KDR and FLT1, are associated with depression and severity of symptoms, suicide ideation and attempts, regardless of both optimal treatment and the presence of early-life stress (ELS) in these associations. also check whether there is an effect of these polymorphisms on the plasma concentrations of proteins expressed by their respective genes and observe whether there is a correlation between VEGF and its inhibitors, VEGF and s100ß. Methodology: 160 patients with depression and 114 healthy controls participated in this study. Questionnaires that assessed the clinical profile of patients, such as the MINI-International Neuropsychiatric Interview, GRID-HAMD21, CTQ, BSI, were applied during interviews, and the number of suicide attempts was recorded. The controls underwent an interview to be evaluated regarding the inclusion and exclusion criteria. The genotyping of the participants was performed using the Real Time PCR technique and protein measurements were performed using the enzyme-linked immunosorbent assay (ELISA). Results: individuals with depression, homozygous AA of the rs699947 polymorphism, had higher plasma concentrations of VEGF (P-value = 0.006) and a greater number of suicide attempts in the direct analysis (P-value = 0.041) and in the corrected analysis a trend towards confirmation of this result was observed (P-value = 0.076). The GG genotype of the FLT1 polymorphism rs7993418 was associated with symptom severity (P-value = 0.040), as well as with a trend for association with increase in suicide attempts and a higher score on the scale that evaluated suicidal ideation. The bigger the plasma concentrations of VEGF, the higher were those of KDR, FLT1 and s100ß. Conclusion: the results indicate that VEGF pathway polymorphisms are associated with the number of suicides and severity of depressive symptoms.

Estudo de associação entre polimorfismos genéticos e níveis plasmáticos do VEGF, FLT1, KDR e o risco para depressão / Study of association between genetic polymorphisms and plasma levels of VEGF, FLT1, KDR and the risk for depression

Introdução: a depressão é um transtorno mental comum, grave e incapacitante que afeta mais de 350 milhões de pessoas em todo o mundo. A depressão é caracterizada principalmente por sintomas como tristeza, perda de interesse, diminuição da energia, perda de confiança e autoestima, culpa inadequada, distúrbios do sono e do apetite, pensamentos de morte e suicídio. Além disso, essa patologia também tem um forte impacto na qualidade de vida dos indivíduos afetados e de suas famílias. Sabe-se que fatores genéticos interagem com as condições socioambientais de modo a influenciar a predisposição das pessoas ao adoecimento. Estudos identificaram polimorfismos de nucleotídeos simples (SNPs) que podem ser marcadores genéticos apropriados para prever inflamação sistêmica, por exemplo, e a atual tese teve como foco o efeito de SNPs na via do fator de crescimento endotelial vascular (VEGF). Esta proteína é uma potente molécula angiogênica e está envolvida na neurogênese do hipocampo, uma das principais estruturas límbicas afetadas em pessoas com depressão. O VEGF está implicado em uma das principais teorias que tentam explicar a fisiopatologia deste transtorno mental grave, a teoria neurotrófica, a qual diz que a diminuição ou desregulação da sinalização de neurotrofinas pode contribuir para a manifestação do transtorno depressivo (TD). Objetivo: avaliar se polimorfismos do VEGF e seus receptores, KDR e FLT1, estão associados à depressão e à gravidade dos sintomas, à ideação e tentativas de suicídio, independentemente tanto de um tratamento otimizado quanto da presença de estresse precoce (do inglês, early-life stress, ELS), também verificar se há efeito destes polimorfismos nas concentrações plasmáticas de proteínas expressas pelos seus respectivos genes e observar se existe correlação entre VEGF e seus inibidores, VEGF e s100ß. Metodologia: participaram do presente estudo 160 pacientes com depressão e 114 controles saudáveis. Foram aplicados durante entrevista questionários que avaliaram o perfil clínico dos pacientes como o MINI-International Neuropsychiatric Interview, GRID-HAMD21, CTQ, BSI e foi registrado o número de tentativas de suicídio. Os controles passaram por uma entrevista para serem avaliados quanto aos critérios de inclusão e exclusão do grupo. A genotipagem dos participantes foi realizada através da técnica de Real Time PCR e as mensurações de proteínas por meio do ensaio ensaio imunoenzimático (ELISA). Resultados: indivíduos com depressão, homozigotos AA do polimorfismo rs699947, apresentaram maiores concentrações plasmáticas de VEGF (P-valor= 0.006) e se associaram a um maior número de tentativas de suicídio na análise direta (P-valor= 0.041) e na análise corrigida foi observada uma tendência para a confirmação deste resultado (P-valor= 0.076). O genótipo homozigoto GG do polimorfismo rs7993418 do FLT1 se associou à severidade de sintomas (P-valor= 0.040), bem como uma tendência de associação com um aumento nas tentativas de suicídio e uma maior pontuação na escala que avaliou ideação suicida. Entre os pacientes quanto maior foram as concentrações plasmáticas de VEGF, maior foram as de KDR, FLT1 e s100ß. Conclusão: os resultados sugerem que os polimorfismos da via VEGF estão associados ao número de tentativas de suicídio e severidade dos sintomas depressivos

Introduction: Depression is a common, serious, and disabling mental disorder that affects more than 350 million people worldwide. Depression is mainly characterized by symptoms such as sadness, loss of interest, decreased energy, loss of confidence and self-esteem, inadequate guilt, sleep and appetite disturbances, thoughts of death and suicide. Furthermore, this pathology also has a strong impact on the quality of life of those affected and their families. It is known that genetic factors interact with social and environmental conditions to influence people's predisposition to illness. Studies have identified single nucleotide polymorphisms (SNPs) that may be appropriate genetic markers to predict systemic inflammation, for example, and the current thesis focused on the effect of SNPs on the vascular endothelial growth factor (VEGF) pathway. This protein is a potent angiogenic molecule and is involved in hippocampal neurogenesis, one of the main limbic structures affected in people with depression. VEGF is implicated in one of the main theories that try to explain the pathophysiology of this severe mental disorder, the neurotrophic theory, which says that the decrease or dysregulation of neurotrophin signaling can contribute to the manifestation of depressive disorder (DT). Objective: to assess whether polymorphisms of VEGF and its receptors, KDR and FLT1, are associated with depression and severity of symptoms, suicide ideation and attempts, regardless of both optimal treatment and the presence of early-life stress (ELS) in these associations. also check whether there is an effect of these polymorphisms on the plasma concentrations of proteins expressed by their respective genes and observe whether there is a correlation between VEGF and its inhibitors, VEGF and s100ß. Methodology: 160 patients with depression and 114 healthy controls participated in this study. Questionnaires that assessed the clinical profile of patients, such as the MINI-International Neuropsychiatric Interview, GRID-HAMD21, CTQ, BSI, were applied during interviews, and the number of suicide attempts was recorded. The controls underwent an interview to be evaluated regarding the inclusion and exclusion criteria. The genotyping of the participants was performed using the Real Time PCR technique and protein measurements were performed using the enzyme-linked immunosorbent assay (ELISA). Results: individuals with depression, homozygous AA of the rs699947 polymorphism, had higher plasma concentrations of VEGF (P-value = 0.006) and a greater number of suicide attempts in the direct analysis (P-value = 0.041) and in the corrected analysis a trend towards confirmation of this result was observed (P-value = 0.076). The GG genotype of the FLT1 polymorphism rs7993418 was associated with symptom severity (P-value = 0.040), as well as with a trend for association with increase in suicide attempts and a higher score on the scale that evaluated suicidal ideation. The bigger the plasma concentrations of VEGF, the higher were those of KDR, FLT1 and s100ß. Conclusion: the results indicate that VEGF pathway polymorphisms are associated with the number of suicides and severity of depressive symptoms

First report of the L1014F kdr mutation in wild populations of Anopheles arabiensis in Cabo Verde, West Africa.

BACKGROUND: Due to the lack of vaccines, malaria control mainly involves the control of anopheline vectors (Anopheles spp.) using chemical insecticides. However, the prolonged and indiscriminate use of these compounds has led to the emergence of resistance in Anopheles populations in Africa. Insecticide resistance surveillance programs are less frequent in Cabo Verde than in other African countries. This study aimed to investigate the circulation of the L1014F and L1014S alleles in natural populations of Anopheles arabiensis collected from two sampling sites in the city of Praia, Cabo Verde. METHODS: Anopheles larvae were collected from the two sampling sites and reared in the laboratory until the adult stage. Mosquitoes were first morphologically identified by classical taxonomy and then by molecular species identification using molecular markers. All Anopheles arabiensis were subjected to PCR analysis to screen for mutations associated to resistance in the Nav gene. RESULTS: A total of 105 mosquitoes, all belonging to the Anopheles gambiae complex, were identified by classical taxonomy as well as by molecular taxonomy. Molecular identification showed that 100% of the An. gambiae senso lato specimens analyzed corresponded to An. arabiensis. Analysis of the Nav gene revealed the presence of L1014S and L1014F alleles with frequencies of 0.10 and 0.19, respectively. CONCLUSIONS: Our data demonstrated, for the first time, the presence of the L1014F allele in the An. arabiensis population from Cabo Verde, as well as an increase in the frequency of the kdr L1014S allele reported in a previous study. The results of this study demonstrate the need to establish new approaches in vector control programs in Cabo Verde.

Impact of selection regime and introgression on deltamethrin resistance in the arbovirus vector Aedes aegypti - a comparative study between contrasted situations in New Caledonia and French Guiana.

BACKGROUND: Pyrethroid insecticides such as deltamethrin have been massively used against Aedes aegypti leading to the spread of resistance alleles worldwide. In an insecticide resistance management context, we evaluated the temporal dynamics of deltamethrin resistance using two distinct populations carrying resistant alleles at different frequencies. Three different scenarios were followed: a continuous selection, a full release of selection, or a repeated introgression with susceptible individuals. The responses of each population to these selection regimes were measured across five generations by bioassays and by monitoring the frequency of knockdown resistance (kdr) mutations and the transcription levels and copy number variations of key detoxification enzymes. RESULTS: Knockdown resistance mutations, overexpression and copy number variations of detoxification enzymes as a mechanism of metabolic resistance to deltamethrin was found and maintained under selection across generations. On comparison, the release of insecticide pressure for five generations did not affect resistance levels and resistance marker frequencies. However, introgressing susceptible alleles drastically reduced deltamethrin resistance in only three generations. CONCLUSION: The present study confirmed that strategies consisting to stop deltamethrin spraying are likely to fail when the frequencies of resistant alleles are too high and the fitness cost associated to resistance is low. In dead-end situations like in French Guiana where alternative insecticides are not available, alternative control strategies may provide a high benefit for vector control, particularly if they favor the introgression of susceptible alleles in natural populations. © 2021 Society of Chemical Industry.

Field-evolved resistance to beta-cyfluthrin in the boll weevil: Detection and characterization.

BACKGROUND: Insecticide resistance in arthropods is an inherited trait that has become a major cause of insect pest control failure. Monitoring the level of susceptibility and characterization of the type of resistance of key pest species aims to determine the risk of resistance selection in time to take action to mitigate control failures. Seven populations of the boll weevil, Anthonomus grandis grandis, collected from cotton fields in the Semiarid and Cerrado areas of Brazil, were screened for their resistance to malathion and beta-cyfluthrin, insecticides widely recommended for control of boll weevil and other pests. RESULTS: The levels of adult mortality were variable for beta-cyfluthrin (0-82%) but invariant (100%) for malathion. Bioassays of concentration-mortality were used to determine lethal concentrations (LCs) for each insecticide. The LC-values corroborate the lack of resistance to field rates of malathion but high levels of resistance to beta-cyfluthrin from 62.7- to 439.7-fold. Weevils resistant to beta-cyfluthrin were found through genome sequencing to possess a kdr mutation through the L1014F substitution in the voltage gated-sodium channel gene. CONCLUSIONS: This study found boll weevil resistance to beta-cyfluthrin to be not mediated by carboxylesterases, but with cross-resistance to DDT and carbaryl, and kdr mutation as the major mechanism of the resistance in our samples. Caution is recommended in further use of beta-cyfluthrin against boll weevil due to potential resistance. Monitoring studies using other boll weevil populations are recommended to determine the geographic pattern and extent of pyrethroid resistance. © 2021 Society of Chemical Industry.