106 research outputs found
Biological and Biochemical Bases of Pesticides Resistance in Rhipicephalus (Boophilus) microplus
Several arthropod species are important vectors of pathogens that cause disease in humans, animals, and plants, including protozoa, nematodes, bacteria, and viruses. Arthropods are also pests competing with humans for food and parasitize farm animals, decreasing their productivity. Historically, arthropod pests and disease vectors affecting public health, crop yields, and livestock production have been managed through the intensive use of pesticides. The widespread use of pesticides is a major problem because most of the economically important arthropod species have developed resistance to currently used pesticides. The impact of pesticide resistance is multifactorial and involves losses due to the heavy use of pesticides, environmental pollution, decreased profitability, food contamination, and public health problems due to pesticide exposure. An indirect consequence of pesticide resistance is the mortality caused by arthropod-borne diseases such as dengue and malaria in humans and babesiosis and anaplasmosis in cattle. The understanding of molecular mechanisms and adaptations to resistance in arthropods is an important issue. However, the molecular mechanisms of pesticide resistance remain to be fully understood. Understanding of resistance mechanisms will contribute significantly to improve integrated managements programs and to discover new targets for vaccine development to mitigate the effects of pesticide-resistant arthropods on agriculture and public health
Integrated Management of the Cattle Tick <em>Rhipicephalus (Boophilus) microplus</em> (Acari: Ixodidae) and the Acaricide Resistance Mitigation
Resistance to insecticides is one of the major obstacles to the control of agricultural pests, as well as species important to human and veterinary health. The World Health Organization has called insecticide resistance âthe great little obstacle against vector-borne diseasesâ. Rhipicephalus (Boophilus) microplus is one of the most important vector, transmitting diseases to cattle such as anaplasmosis and babesiosis. These diseases cause great economic losses that significantly increased because of the appearance of tick populations resistant to acaricides, as a result of the intensive use of pesticides. Resistance to ixodicides in Latin America is a growing problem, since control of disease-transmitting ticks, depends heavily on the use of pesticides. In Mexico, the resistance of R. microplus to organophosphate compounds, pyrethroids, and recently amidines, has been detected in some areas, affected by multiple acaricide resistance to the three families of ixodicides. The cattle tick R. microplus in addition to the great ecological impact represents the most expensive pest for livestock in Mexico, since the producers are directly affected by this tick, due to the decrease in the production of meat, milk and damage to the skin, as well as the indirect damage, such as the transmission of diseases, including Anaplasmosis and Babesiosis, which, in turn, represents a serious limitation for the introduction of specialized cattle in endemic areas. Therefore, the use of integrated management programs is a mandatory issue that should be implemented in all those areas affected by this parasite
Frecuencia e identificaciĂłn molecular de Cryptosporidium spp en becerras lactantes mantenidas en confinamiento en Aguascalientes, MĂ©xico
In order to determine the frequency of Cryptosporidium spp and to identify the species or genotype of oocysts found in confined, suckling lactating calves in Aguascalientes, Mexico dairies, fecal samples were collected from 8-14-d old-calves in eight different dairies. Samples were smeared, Kinyoun-stained and subjected to nested PCR in order to amplify parasite's 18S rRNA region (830 bp). Positive samples were cloned on a pGEM-T vector then sequenced. Frequency of animals positive to Cryptosporidium spp by microscopy was 75 % (95/126), with a 25 to 100 % range among dairies, even though, using molecular techniques the frequency of positive animals was 67 % (85/126), with a 20 to 100 % range among dairies. All other samples were negative to both tests. All samples sequenced had a 100 % homology with the 18S rRNA region of C. parvum. Results confirm the relevance of C. parvum as a major etiology of cryptosporidiosis in suckling dairy calves and show its broad distribution in the area. Given that C. parvum is a zoonotic species, calf managers should be considered as broadly exposed to the infection.Con el objeto de determinar la frecuencia de Cryptosporidium spp, y realizar la identificaciĂłn de especie o genotipo de los ooquistes encontrados, en becerras lactantes mantenidas en confinamiento en establos lecheros de Aguascalientes, MĂ©xico, se tomaron muestras de excremento de 126 becerras de 8 a 14 dĂas de edad provenientes de ocho establos, las cuales fueron procesadas mediante frotis fecal teñido con Kinyoun y por PCR anidada para amplificar la regiĂłn 18S rARN del parĂĄsito (830 pb), las muestras positivas fueron clonadas en un vector pGEM-T y secuenciadas. La frecuencia de animales positivos a Cryptosporidium spp por microscopĂa fue de 75 % (95/126), con una escala entre establos de 25 a 100 %, en tanto que por tĂ©cnicas moleculares fue de 67 % (85/126), con escala entre establos de 20 a 100 %, el resto de las muestras fueron negativas en ambas pruebas. Todas las muestras secuenciadas tuvieron una homologĂa del 100 % con la regiĂłn 18S rARN de C. parvum. Estos resultados confirman la importancia de C. parvum como principal agente de la criptosporidiosis en becerras lactantes y demuestra su amplia distribuciĂłn en la zona, debido a que C. parvum es una especie zoonĂłtica, debe de considerarse que las personas que manejan a las becerras se encuentran ampliamente expuestas a la infecciĂłn
Variants in toll-like receptor 9 gene influence susceptibility to tuberculosis in a Mexican population
Background: The control of Mycobacterium tuberculosis (Mtb) infection begins with the recognition of mycobacterial structural components by toll like receptors (TLRs) and other pattern recognition receptors. Our objective was to determine the influence of TLRs polymorphisms in the susceptibility to develop tuberculosis (TB) in Amerindian individuals from a rural area of Oaxaca, Mexico with high TB incidence. Methods: We carried out a caseâcontrol association community based study, genotyping 12 polymorphisms of TLR2, TLR4, TLR6 and TLR9 genes in 90 patients with confirmed pulmonary TB and 90 unrelated exposed but asymptomatic household contacts. Results: We found a significant increase in the frequency of the allele A of the TLR9 gene polymorphism rs352139 (A>G) in the group of TB patients (g.f. = 0.522) when compared with controls (g.f. = 0.383), (Pcorr = 0.01, OR = 1.75). Under the recessive model (A/G + A/A vs G/G) this polymorphism was also significantly associated with TB (Pcorr = 0.01, OR= 2.37). The association of the SNP rs352139 was statistically significant after adjustment by age, gender and comorbidities by regression logistic analysis (Dominant model: p value = 0.016, OR = 2.31; Additive model: p value = 0.023, OR = 1.68). The haplotype GAA of TLR9 SNPs was also associated with TB susceptibility (Pcorr = 0.02). Differences in the genotype or allele frequencies of TLR2, TLR4 and TLR6 polymorphisms between TB patients and healthy contacts were not detected. Conclusions: Our study suggests that the allele A of the intronic polymorphism rs352139 on TLR9 gene might contribute to the risk of developing TB in Mexican Amerindians
Molecular survey of pyrethroid resistance mechanisms in Mexican field populations of Rhipicephalus (Boophilus) microplus
Susceptibility to synthetic pyrethroids (SPÂŽs) and the role of two major resistance mechanisms were evaluated in Mexican Rhipicephalus microplus tick populations. Larval packet test (LPT), knock-down (kdr) PCR allele-specific assay (PASA) and esterase activity assays were conducted in tick populations for cypermethrin, flumethrin and deltamethrin. Esterase activity did not have a significant correlation with SPÂŽs resistance. However a significant correlation (pâ<â0.01) was found between the presence of the sodium channel mutation, and resistance to SPÂŽs as measured by PASA and LPT respectively. Just over half the populations (16/28) were cross-resistant to flumethrin, deltamethrin and cypermethrine, 21.4% of the samples (6/28) were susceptible to all of the three pyrethroids 10.7 of the samples (3/28) were resistant to flumethrin, 3.4 of the samples (1/28) were resistant to deltamethrin only and 7.1% (2/28) were resistant to flumethrin and deltamethrin. The presence of the kdr mutation correlates with resistance to the SPÂŽs as a class. Target site insensitivity is the major mechanism of resistance to SPÂŽs in Mexican R. microplus field strains, involving the presence of a sodium channel mutation, however, esterase-based, other mutations or combination of mechanisms can also occur
The immunogenetic diversity of the HLA system in Mexico correlates with underlying population genetic structure
We studied HLA class I (HLA-A, -B) and class II (HLA-DRB1, -DQB1) allele groups and alleles by PCR-SSP based typing in a total of 15,318 mixed ancestry Mexicans from all the states of the country divided into 78 sample sets, providing information regarding allelic and haplotypic frequencies and their linkage disequilibrium, as well as admixture estimates and genetic substructure. We identified the presence of 4268 unique HLA extended haplotypes across Mexico and find that the ten most frequent (HF > 1%) HLA haplotypes with significant linkage disequilibrium (Îââ„0.1) in Mexico (accounting for 20% of the haplotypic diversity of the country) are of primarily Native American ancestry (A*02~B*39~DRB1*04~DQB1*03:02, A*02~B*35~DRB1*08~DQB1*04, A*68~B*39~DRB1*04~DQB1*03:02, A*02~B*35~DRB1*04~DQB1*03:02, A*24~B*39~DRB1*14~DQB1*03:01, A*24~B*35~DRB1*04~DQB1*03:02, A*24~B*39~DRB1*04~DQB1*03:02, A*02~B*40:02~DRB1*04~DQB1*03:02, A*68~B*35~DRB1*04~DQB1*03:02, A*02~B*15:01~DRB1*04~DQB1*03:02). Admixture estimates obtained by a maximum likelihood method using HLA-A/-B/-DRB1 as genetic estimators revealed that the main genetic components in Mexico as a whole are Native American (ranging from 37.8% in the northern part of the country to 81.5% in the southeastern region) and European (ranging from 11.5% in the southeast to 62.6% in northern Mexico). African admixture ranged from 0.0 to 12.7% not following any specific pattern. We were able to detect three major immunogenetic clusters correlating with genetic diversity and differential admixture within Mexico: North, Central and Southeast, which is in accordance with previous reports using genome-wide data. Our findings provide insights into the population immunogenetic substructure of the whole country and add to the knowledge of mixed ancestry Latin American population genetics, important for disease association studies, detection of demographic signatures on population variation and improved allocation of public health resources.Fil: Barquera, Rodrigo. Max Planck Institute For The Science Of Human History; Alemania. Instituto Nacional de AntropologĂa E Historia. Escuela Nacional de AntropologĂa E Historia; MĂ©xicoFil: HernĂĄndez Zaragoza, Diana IraĂz. TĂ©cnicas GenĂ©ticas Aplicadas A la ClĂnica (tgac); MĂ©xico. Instituto Nacional de AntropologĂa E Historia. Escuela Nacional de AntropologĂa E Historia; MĂ©xicoFil: Bravo Acevedo, Alicia. Instituto Mexicano del Seguro Social; MĂ©xicoFil: Arrieta Bolaños, Esteban. Universitat Essen; AlemaniaFil: Clayton, Stephen. Max Planck Institute For The Science Of Human History; AlemaniaFil: Acuña Alonzo, VĂctor. Instituto Nacional de AntropologĂa E Historia, Mexico; MĂ©xicoFil: MartĂnez Ălvarez, Julio CĂ©sar. Instituto Mexicano del Seguro Social; MĂ©xicoFil: LĂłpez Gil, ConcepciĂłn. Instituto Mexicano del Seguro Social; MĂ©xicoFil: Adalid SĂĄinz, Carmen. Instituto Mexicano del Seguro Social; MĂ©xicoFil: Vega MartĂnez, MarĂa del Rosario. Hospital Central Sur de Alta Especialidad; MĂ©xicoFil: Escobedo RuĂz, Araceli. Instituto Mexicano del Seguro Social; MĂ©xicoFil: JuĂĄrez CortĂ©s, Eva Dolores. Instituto Mexicano del Seguro Social; MĂ©xicoFil: Immel, Alexander. Max Planck Institute For The Science Of Human History; Alemania. Christian Albrechts Universitat Zu Kiel; AlemaniaFil: Pacheco Ubaldo, Hanna. Instituto Nacional de AntropologĂa E Historia. Escuela Nacional de AntropologĂa E Historia; MĂ©xicoFil: GonzĂĄlez Medina, Liliana. Instituto Nacional de AntropologĂa E Historia. Escuela Nacional de AntropologĂa E Historia; MĂ©xicoFil: Lona SĂĄnchez, Abraham. Instituto Nacional de AntropologĂa E Historia. Escuela Nacional de AntropologĂa E Historia; MĂ©xicoFil: Lara Riegos, Julio. Universidad AutĂłnoma de YucatĂĄn; MĂ©xicoFil: SĂĄnchez FernĂĄndez, MarĂa Guadalupe de JesĂșs. Instituto Mexicano del Seguro Social; MĂ©xicoFil: DĂaz LĂłpez, Rosario. Hospital Central Militar, Mexico City; MĂ©xicoFil: Guizar LĂłpez, Gregorio Ulises. Hospital Central Militar, Mexico City; MĂ©xicoFil: Medina Escobedo, Carolina Elizabeth. Instituto Mexicano del Seguro Social; MĂ©xicoFil: Arrazola GarcĂa, MarĂa Araceli. Instituto Mexicano del Seguro Social; MĂ©xicoFil: Montiel HernĂĄndez, Gustavo Daniel. Instituto Nacional de AntropologĂa E Historia. Escuela Nacional de AntropologĂa E Historia; MĂ©xicoFil: HernĂĄndez HernĂĄndez, Ofelia. TĂ©cnicas GenĂ©ticas Aplicadas a la ClĂnica ; MĂ©xicoFil: Ramos de la Cruz, Flor del RocĂo. Instituto Mexicano del Seguro Social; MĂ©xicoFil: JuĂĄrez NicolĂĄs, Francisco. Instituto Nacional de PediatrĂa; MĂ©xicoFil: Pantoja Torres, Jorge Arturo. Instituto Mexicano del Seguro Social; MĂ©xicoFil: RodrĂguez MunguĂa, Tirzo JesĂșs. Hospital General Norberto Treviño Zapata; MĂ©xicoFil: JuĂĄrez Barreto, Vicencio. Hospital Infantil de Mexico Federico Gomez; MĂ©xicoFil: Gonzalez-Jose, Rolando. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Centro Nacional PatagĂłnico. Instituto PatagĂłnico de Ciencias Sociales y Humanas; Argentin
From colorectal cancer pattern to the characterization of individuals at risk: Picture for genetic research in Latin America
Colorectal cancer (CRC) is one of the most common cancers in Latin America and the Caribbean, with the highest rates reported for Uruguay, Brazil and Argentina. We provide a global snapshot of the CRC patterns, how screening is performed, and compared/contrasted to the genetic profile of Lynch syndrome (LS) in the region. From the literature, we find that only nine (20%) of the Latin America and the Caribbean countries have developed guidelines for early detection of CRC, and also with a low adherence. We describe a genetic profile of LS, including a total of 2,685 suspected families, where confirmed LS ranged from 8% in Uruguay and Argentina to 60% in Peru. Among confirmed LS, path_MLH1 variants were most commonly identified in Peru (82%), Mexico (80%), Chile (60%), and path_MSH2/EPCAM variants were most frequently identified in Colombia (80%) and Argentina (47%). Path_MSH6 and path_PMS2 variants were less common, but they showed important presence in Brazil (15%) and Chile (10%), respectively. Important differences exist at identifying LS families in Latin American countries, where the spectrum of path_MLH1 and path_MSH2 variants are those most frequently identified. Our findings have an impact on the evaluation of the patients and their relatives at risk for LS, derived from the gene affected. Although the awareness of hereditary cancer and genetic testing has improved in the last decade, it is remains deficient, with 39%â80% of the families not being identified for LS among those who actually met both the clinical criteria for LS and showed MMR deficiency.Fil: Vaccaro, Carlos Alberto. Hospital Italiano; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: LĂłpez Kostner, Francisco. No especifĂca;Fil: Adriana, Della Valle. Hospital Fuerzas Armadas; UruguayFil: Inez Palmero, Edenir. Hospital de cĂĄncer de Barretos, FACISB; BrasilFil: Rossi, Benedito Mauro. Hospital Sirio Libanes; BrasilFil: Antelo, Marina. Gobierno de la Ciudad de Buenos Aires. Hospital de GastroenterologĂa "Dr. Carlos B. Udaondo"; Argentina. Universidad Nacional de LanĂșs; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Solano, Angela Rosario. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay. Instituto de Investigaciones BiomĂ©dicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones BiomĂ©dicas; ArgentinaFil: Carraro, Dirce Maria. No especifĂca;Fil: Forones, Nora Manoukian. Universidade Federal de Sao Paulo; BrasilFil: Bohorquez, Mabel. Universidad del Tolima; ColombiaFil: Lino Silva, Leonardo S.. Instituto Nacional de Cancerologia; MĂ©xicoFil: Buleje, Jose. Universidad de San MartĂn de Porres; PerĂșFil: Spirandelli, Florencia. No especifĂca;Fil: Abe Sandes, Kiyoko. Universidade Federal da Bahia; BrasilFil: Nascimento, Ivana. No especifĂca;Fil: Sullcahuaman, Yasser. Universidad Peruana de Ciencias Aplicadas; PerĂș. Instituto de InvestigaciĂłn Genomica; PerĂșFil: Sarroca, Carlos. Hospital Fuerzas Armadas; UruguayFil: Gonzalez, Maria Laura. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay. Instituto de Medicina Traslacional e IngenierĂa BiomĂ©dica - Hospital Italiano. Instituto de Medicina Traslacional e IngenierĂa BiomĂ©dica.- Instituto Universitario Hospital Italiano de Buenos Aires. Instituto de Medicina Traslacional e IngenierĂa BiomĂ©dica; ArgentinaFil: Herrando, Alberto Ignacio. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay. Instituto de Medicina Traslacional e IngenierĂa BiomĂ©dica - Hospital Italiano. Instituto de Medicina Traslacional e IngenierĂa BiomĂ©dica.- Instituto Universitario Hospital Italiano de Buenos Aires. Instituto de Medicina Traslacional e IngenierĂa BiomĂ©dica; ArgentinaFil: Alvarez, Karin. No especifĂca;Fil: Neffa, Florencia. Hospital Fuerzas Armadas; UruguayFil: GalvĂŁo, Henrique Camposreis. Barretos Cancer Hospital; BrasilFil: Esperon, Patricia. Hospital Fuerzas Armadas; UruguayFil: Golubicki, Mariano. Gobierno de la Ciudad de Buenos Aires. Hospital de GastroenterologĂa "Dr. Carlos B. Udaondo"; ArgentinaFil: Cisterna, Daniel. Gobierno de la Ciudad de Buenos Aires. Hospital de GastroenterologĂa "Dr. Carlos B. Udaondo"; ArgentinaFil: Cardoso, Florencia C.. Centro de EducaciĂłn Medica E Invest.clinicas; ArgentinaFil: Tardin Torrezan, Giovana. No especifĂca;Fil: Aguiar Junior, Samuel. No especifĂca;Fil: Aparecida Marques Pimenta, CĂ©lia. Universidade Federal de Sao Paulo; BrasilFil: Nirvana da Cruz Formiga, MarĂa. No especifĂca;Fil: Santos, Erika. Hospital Sirio Libanes; BrasilFil: SĂĄ, Caroline U.. Hospital Sirio Libanes; BrasilFil: Oliveira, Edite P.. Hospital Sirio Libanes; BrasilFil: Fujita, Ricardo. Universidad de San MartĂn de Porres; PerĂșFil: Spirandelli, Enrique. No especifĂca;Fil: Jimenez, Geiner. No especifĂca;Fil: Santa Cruz Guindalini, Rodrigo. Universidade de Sao Paulo; BrasilFil: Gondim Meira Velame de Azevedo, Renata. No especifĂca;Fil: Souza Mario Bueno, Larissa. Universidade Federal da Bahia; BrasilFil: dos Santos Nogueira, Sonia Tereza. No especifĂca;Fil: Piñero, Tamara Alejandra. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Houssay. Instituto de Medicina Traslacional e IngenierĂa BiomĂ©dica - Hospital Italiano. Instituto de Medicina Traslacional e IngenierĂa BiomĂ©dica.- Instituto Universitario Hospital Italiano de Buenos Aires. Instituto de Medicina Traslacional e IngenierĂa BiomĂ©dica; Argentin
Identification and characterization of Rhipicephalus (Boophilus) microplus candidate protective antigens for the control of cattle tick infestations
The cattle ticks, Rhipicephalus (Boophilus) spp., affect cattle production in tropical and subtropical regions of the world. Tick vaccines constitute a cost-effective and environmentally friendly alternative to tick control. The recombinant Rhipicephalus microplus Bm86 antigen has been shown to protect cattle against tick infestations. However, variable efficacy of Bm86-based vaccines against geographic tick strains has encouraged the research for additional tick-protective antigens. Herein, we describe the analysis of R. microplus glutathione-S transferase, ubiquitin (UBQ), selenoprotein W, elongation factor-1 alpha, and subolesin (SUB) complementary DNAs (cDNAs) by RNA interference (RNAi) in R. microplus and Rhipicephalus annulatus. Candidate protective antigens were selected for vaccination experiments based on the effect of gene knockdown on tick mortality, feeding, and fertility. Two cDNA clones encoding for UBQ and SUB were used for cattle vaccination and infestation with R. microplus and R. annulatus. Control groups were immunized with recombinant Bm86 or adjuvant/saline. The highest vaccine efficacy for the control of tick infestations was obtained for Bm86. Although with low immunogenic response, the results with the SUB vaccine encourage further investigations on the use of recombinant subolesin alone or in combination with other antigens for the control of cattle tick infestations. The UBQ peptide showed low immunogenicity, and the results of the vaccination trial were inconclusive to assess the protective efficacy of this antigen. These experiments showed that RNAi could be used for the selection of candidate tick-protective antigens. However, vaccination trials are necessary to evaluate the effect of recombinant antigens in the control of tick infestations, a process that requires efficient recombinant protein production and formulation systems
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