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Vânia Rita Elias Pinheiro Bittencourt - One of the best experts on this subject based on the ideXlab platform.

  • Effects of fluazuron on the biological parameters of engorged females of Rhipicephalus microplus
    2020
    Co-Authors: Fabrício Nascimento Gaudêncio, Vânia Rita Elias Pinheiro Bittencourt, Isabele Da Costa Angelo, Matheus Dias Cordeiro, Adivaldo Henrique Da Fonseca, Jaqueline De Almeida Valim Rodrigues, Bruna De Azevedo Baêta, Jairo Pinheiro
    Abstract:

    The objective of this study was to evaluate the biological parameters of Rhipicephalus microplus engorged females exposed to the arthropod growth regulator fluazuron. A commercial formulation based on fluazuron (Acatak®, Novartis) was administered topically to stabled cattle artificially infested with R. microplus larvae. The infestations occurred on four alternate days (days -21, -17, -13 and -6) taking as day 0 (zero) the day of treatment with a single dose of fluazuron for the treated group. Fifteen engorged females from each group were collected from the floor of the stalls at the end of the engorgement period (21 days) on pre-established days: before (day 0) and after treatment (days 4, 8 and 15), respectively. After cleaning and preparation of the engorged females in the laboratory, the following biological parameters were analyzed: weight of the engorged female, weight of the female after laying (spent female), laying period, weight of the posture, egg production index, reproductive efficiency index, hatching percentage, and nutritional index. The average weight of engorged females showed a significant reduction on all days after treatment in the exposed group. Aside from the weight after laying, all other biological parameters showed a significant reduction on the eighth post-treatment day due to exposure to fluazuron. Knowledge of the effects of an active principle on biological parameters in a population of ticks is essential for appropriate implementation of integrated management practices for parasite control.

  • In vitro pathogenicity of different Metarhizium anisopliae s.l. isolates in oil formulations against Rhipicephalus microplus
    Biocontrol Science and Technology, 2017
    Co-Authors: Wendell Marcelo De Souza Perinotto, Mariana Guedes Camargo, Caio Junior Balduino Coutinho Rodrigues, Isabele Da Costa Angelo, Patrícia Silva Gôlo, Simone Quinelato, Allan Felipe Marciano, Caio Márcio De Oliveira Monteiro, Vânia Rita Elias Pinheiro Bittencourt
    Abstract:

    ABSTRACTThe present study aimed to evaluate the in vitro pathogenicity of the Metarhizium anisopliae s.l. CG 112, CG 347, CG 32, CG 148 and CG 629 isolates formulated in vegetable or mineral oil against Rhipicephalus microplus. The bioassays were performed with R. microplus engorged females. The ticks were immersed for three minutes in oil-based formulations containing 10% oil (mineral or vegetable). The effects of the different fungal isolates were evaluated analyzing the females’ reproductive parameters (the total weight of the egg mass, hatching percentage, egg production index and nutritional index). The present study showed that all of the tested isolates and both oil formulations (vegetable or mineral oil) changed the biological parameters of the R. microplus females. However, the mineral oil formulation was more effective than the vegetable oil formulation, as the former showed a higher tick control percentage. It was concluded that there was variation in the virulence among the different M. anisop...

  • Receptores Toll-like em corpo gorduroso e glândula salivar do carrapato bovino Rhipicephalus microplus
    2016
    Co-Authors: Sabrina Rita Da Fonseca Rezende, Marcio Fontenele, Claudio Akio Masuda, Pedro L. Oliveira, Helena Araujo, Vânia Rita Elias Pinheiro Bittencourt, Milane De Souza Leite
    Abstract:

    ABSTRACT. Rezende S.deF., Fontenele M.R., Masuda C.A., de Oliveira P.L., Araujo H.M.M., Bittencourt V.R.E.P. & Leite M.de S. Toll-like receptors in fat body and salivary gland tissues in the cattle tick Rhipicephalus microplus. [Receptores Toll-like em corpo gorduroso e glândula salivar do carrapato bovino Rhipicephalus microplus]. Revista Brasileira de Medicina Veterinaria, 38(supl. 3):47-53, 2016. Programa de Pos-Graduacao em Ciencias Veterinarias, Anexo 1, Instituto de Veterinaria, Universidade Federal Rural do Estado do Rio de Janeiro, BR 465, KM 47, Seropedica, RJ 23890-000, Brasil. E-mail: milaneleite@ufrrj.br Toll-like receptors (TLRs) play an important role in the recognition of pathogen components and subsequent activation of the innate immune response, which then leads to development of immune responses. In arthropods the fat body and salivary glands are important organs in the defense system against invading pathogens. In this study, we identified for the first time the presence of TLRs in fat body and salivary gland tissues of cattle tick Rhipicephalus microplus. Our results show that the expression of TLRs in fat body tissue are not found in all cells, but is specific to some cell types, in salivary glands TLRs protein expression occur in acini structure. We suggest that immune pathways are active in both fat body and salivary glands in the tick. The potential use of TLRs as a target for vaccine formulations against is discussed.

  • Estudo morfológico de isolados de Beauveria bassiana antes e após reisolamento em Rhipicephalus microplus
    2016
    Co-Authors: Caio Junior Balduino Coutinho Rodrigues, Mariana Guedes Camargo, Wendell Marcelo De Souza Perinotto, Isabele Da Costa Angelo, Simone Quinelato, Maria Clemente De Freitas, Fernanda Da Silva Santos, Jéssica Fiorotti De Paulo, Vânia Rita Elias Pinheiro Bittencourt
    Abstract:

    ABSTRACT. Coutinho-Rodrigues C.J.B., de Freitas M.C., Perinotto W.M.deS., Santos F.S., de Paulo J.F., Quinelato S., Camargo M.G., Angelo I.daC. & Bittencourt V.R.E.P. [Morphological study and conidia production of Beauveria bassiana isolates before and after reisolation in Rhipicephalus microplus]. Estudo morfologico de isolados de Beauveria bassiana antes e apos reisolamento em Rhipicephalus microplus Revista Brasileira de Medicina Veterinaria, 38(supl. 3):54-65, 2016. Departamento de Parasitologia Animal, Anexo 1, Instituto de Veterinaria, Universidade Federal Rural do Rio de Janeiro, BR 465, KM 47, Seropedica, RJ 23890-000, Brasil. E-mail: vaniabit@ufrrj.br Beauveria bassiana is a cosmopolitan arthropod pathogenic fungus that possesses the cattle tick Rhipicephalus microplus as host. In this context, studies involving morphology and production of conidia on culture medium may indicate isolates that have potential for using in wide-scale. The present study evaluated the macro and the micromorphology, in addition to the conidia production of ten B. bassiana isolates before and after one passage (development cycle) on R. microplus. Macroscopically, variations in diameter, surface, texture, exudation and reverse coloration were observed after reisolation. On the other hand, the process did not alter the development of conidiophores, the shape and size of conidia. Regarding the conidiation, six isolates increased the number of conidia counted per area. Highlighting, the isolate Bb 02, which has the tick as the original host, presented an increase of the powdery and conidia production posteriorly of a single passage. Thus, it is believed that for future commercial evaluations, studies involving more passages in potential hosts, as well as their association to pathogenicity and enzymatic activity analyzes, may express more relevant results for biological control.

  • Formulações oleosas contendo fungos artropodopatogênicos para o controle de Rhipicephalus microplus
    2015
    Co-Authors: Isabele Da Costa Angelo, Mariana Guedes Camargo, Wendell Marcelo De Souza Perinotto, Patrícia Silva Gôlo, Simone Quinelato, Hilton Carmo Diniz Neto, Samilla V. Santos, Huarrisson Azevedo Santos, Allan Felipe Marciano, Vânia Rita Elias Pinheiro Bittencourt
    Abstract:

    ABSTRACT. Angelo I.C., Diniz-Neto H.C., Santos S.V., Perinotto W.M.S., Quinelato S., Santos H.A., Golo P.S., Camargo M.G., Marciano A.F. & Bittencourt V.R.E.P. [Oil-based formulations containing arthropodpathogenic fungi to control Rhipicephalus microplus.] Formulacoes oleosas contendo fungos artropodopatogenicos para o controle de Rhipicephalus microplus. Revista Brasileira de Medicina Veterinaria, 37(Supl.1):18-24, 2015. Departamento de Epidemiologia e Saude Publica, Universidade Federal Rural do Estado do Rio de Janeiro, BR 465, Km 7, Seropedica, RJ 23897-970, Brasil. E-mail: isabeleangelo@yahoo.com.br Rhipicephalus microplus ticks are responsible for economical losses estimated in U$ 3.24 billions per year in Brazil. Arthropodpathogenic fungi are an important alternative to the chemical control of this arthropod; however to be efficient in the field, formulations must be developed to protect conidia against environmental stresses. The present study compared the efficacy of mineral or vegetal oil-based formulations containing Metarhizium anisopliae s.l. or Beauveria bassiana s.l. as well as their association to control R. microplus engorged females. M. anisopliae and B. bassiana isolates were cultivated in Potato Dextrose Agar medium and maintained under optimal conditions. Single fungus oil-based formulations were prepared with the following proportions: 84% aqueous fungal suspension; 15% sterile oil; 1% Tween 80. Associated fungal formulations were prepared as follows: 42% aqueous M. anisopliae suspension; 42% aqueous B. bassiana suspension; 15% sterile oil and 1% Tween. Engorged females were immersed in 1 mL oil formulations. The following biological parameters were evaluated: initial weigh of engorged female; weight of egg mass; egg production index; nutritional index and percentage of tick control. There was no difference in the percentage of tick control when M. anisopliae s.l. and/or B. bassiana s.l. were tested in mineral oil. Although, when vegetable oil-based formulations were tested, only M. anisopliae s.l. formulations (both single and associated) had satisfactory control percentage (41.97% and 40. 13%) while single fungus B. bassiana s.l. formulation yield a very low percentage of tick control (10.88%). Accordingly, the use of different oils (mineral or vegetable oils) may affect in different ways the arthropodpathogenic fungi efficacy to control R. microplus. Therefore, different oils should be tested in formulations to control ticks, as well as their interactions with different fungal isolates what will contribute to the development of a promising alternative to control this important parasite.

John R Yates - One of the best experts on this subject based on the ideXlab platform.

  • blood anticlotting activity of a Rhipicephalus microplus cathepsin l like enzyme
    Biochimie, 2019
    Co-Authors: Marina Amaral Xavier, Ricardo J.s. Torquato, Adriana Seixas, Itabajara Da Silva Vaz, Antônio F.m. Pinto, Lucas Tirloni, John R Yates, Aparecida Tanaka, Jolene K Diedrich, Carlos Termignoni
    Abstract:

    Abstract In parasites, cathepsins are implicated in mechanisms related to organism surveillance and host evasion. Some parasite cathepsins have fibrinogenolytic and fibrinolytic activity, suggesting that they may contribute to maintain blood meal fluidity for extended feeding periods. Here, it is shown that BmGTI (Rhipicephalus [Boophilus] microplus Gut Thrombin Inhibitor), a protein previously described as an inhibitor of fibrinogen hydrolysis and platelet aggregation by thrombin, and BmCL1 (Rhipicephalus [Boophilus] microplus Cathepsin-L like 1) are the same protein, hereinafter referred to using the earliest name (BmCL1). To further characterize BmCL1, Rhipicephalus microplus native and recombinant (rBmCL1) proteins were obtained. Native BmCL1 was isolated using thrombin-affinity chromatography, and it displays thrombin inhibition activity. We subsequently investigated rBmCL1 interaction with thrombin. We show that rBmCL1 and thrombin have a dissociation constant (ΚD) of 130.2 ± 11.2 nM, and this interaction likely occurs due to a more electronegative surface of BmCL1 at pH 7.5 than at pH 5.0, which may favor an electrostatic binding to positively charged thrombin exosites. During BmCL1-thrombin interaction, thrombin is not degraded or inhibited. rBmCL1 impairs thrombin-induced fibrinogen clotting via a fibrinogenolytic activity. Fibrinogen degradation by BmCL1 occurs by the hydrolysis of Aα- and Bβ-chains, generating products similar to those produced by fibrinogenolytic cathepsins from other organisms. In conclusion, BmCL1 likely has an additional role in R. microplus blood digestion, besides its role in hemoglobin degradation at acid pH. BmCL1 fibrinogenolytic activity indicates a proteolytic activity in the neutral lumen of tick midgut, contributing to maintain the fluidity of the ingested blood, which remains to be confirmed in vivo.

  • Secretomic analysis of Beauveria bassiana related to cattle tick, Rhipicephalus microplus, infection
    Folia Microbiologica, 2019
    Co-Authors: Lucélia Santi, John R Yates, Wendell M.s. Perinotto, Caio J. B. Coutinho-rodrigues, Markus Berger, Lisete A. S. Klein, Eduardo M. Souza, Rafael L. Rosa, Jorge A. Guimarães, Vânia R. E. P. Bittencourt
    Abstract:

    Beauveria bassiana is widely studied as an alternative to chemical acaricides in controlling the cattle tick Rhipicephalus microplus. Although its biocontrol efficiency has been proved in laboratory and field scales, there is a need to a better understanding of host interaction process at molecular level related to biocontrol activity. In this work, applying a proteomic technique multidimensional protein identification technology (MudPIT), the differential secretome of B. bassiana induced by the host R. microplus cuticle was evaluated. The use of the host cuticle in a culture medium, mimicking an infection condition, is an established experimental model that triggers the secretion of inducible enzymes. From a total of 236 proteins, 50 proteins were identified exclusively in infection condition, assigned to different aspects of infection like host adhesion, cuticle penetration and fungal defense, and stress. Other 32 proteins were considered up- or down-regulated. In order to get a meaningful global view of the secretome, several bioinformatic analyses were performed. Regarding molecular function classification, the highest number of proteins in the differential secretome was assigned in to hydrolase activity, enzyme class of all cuticle-degrading enzymes like lipases and proteases. These activities were also further validated through enzymatic assays. The results presented here reveal dozens of specific proteins and different processes potentially implicated in cattle tick infection improving the understanding of molecular basis of biocontrol of B. bassiana against R. microplus.

  • expression profile of Rhipicephalus microplus vitellogenin receptor during oogenesis
    Ticks and Tick-borne Diseases, 2018
    Co-Authors: Adriana Seixas, Antônio F.m. Pinto, Mara Fernanda A Alzugaray, Lucas Tirloni, Luis Fernando Parizi, Naftaly Wangâombe Githaka, Satoru Konnai, Kazuhiko Ohashi, John R Yates
    Abstract:

    The vitellogenin receptor (VgR), which belongs to the low-density lipoprotein receptors (LDLR) family, regulates the absorption of yolk protein accumulated in developing oocytes during oogenesis. In the present study, the full sequence of Rhipicephalus microplus VgR (RmVgR) and the partial sequence of Rhipicephalus appendiculatus VgR (RaVgR) ORF were determined and cloned. The RmVgR amino acid sequence contains the five highly conserved structural motifs characteristic of LDLR superfamily members, the same overall structure as observed in other species. Phylogenetic analysis separated VgRs in two major groups, corresponding to receptors from acarines and insects. Consistent with observations from other arthropods, RmVgR was specifically expressed in the ovarian tissue and its peak of expression occurs in females that are detaching from the host. Silencing with RmVgR dsRNA reduced VgR expression, which resulted in reduced fertility, evidenced by a decrease in the number of larvae. The present study confirms RmVgR is a specific receptor involved in yolk protein uptake and oocyte maturation in R. microplus, playing an important role in tick reproduction.

Antônio F.m. Pinto - One of the best experts on this subject based on the ideXlab platform.

  • blood anticlotting activity of a Rhipicephalus microplus cathepsin l like enzyme
    Biochimie, 2019
    Co-Authors: Marina Amaral Xavier, Ricardo J.s. Torquato, Adriana Seixas, Itabajara Da Silva Vaz, Antônio F.m. Pinto, Lucas Tirloni, John R Yates, Aparecida Tanaka, Jolene K Diedrich, Carlos Termignoni
    Abstract:

    Abstract In parasites, cathepsins are implicated in mechanisms related to organism surveillance and host evasion. Some parasite cathepsins have fibrinogenolytic and fibrinolytic activity, suggesting that they may contribute to maintain blood meal fluidity for extended feeding periods. Here, it is shown that BmGTI (Rhipicephalus [Boophilus] microplus Gut Thrombin Inhibitor), a protein previously described as an inhibitor of fibrinogen hydrolysis and platelet aggregation by thrombin, and BmCL1 (Rhipicephalus [Boophilus] microplus Cathepsin-L like 1) are the same protein, hereinafter referred to using the earliest name (BmCL1). To further characterize BmCL1, Rhipicephalus microplus native and recombinant (rBmCL1) proteins were obtained. Native BmCL1 was isolated using thrombin-affinity chromatography, and it displays thrombin inhibition activity. We subsequently investigated rBmCL1 interaction with thrombin. We show that rBmCL1 and thrombin have a dissociation constant (ΚD) of 130.2 ± 11.2 nM, and this interaction likely occurs due to a more electronegative surface of BmCL1 at pH 7.5 than at pH 5.0, which may favor an electrostatic binding to positively charged thrombin exosites. During BmCL1-thrombin interaction, thrombin is not degraded or inhibited. rBmCL1 impairs thrombin-induced fibrinogen clotting via a fibrinogenolytic activity. Fibrinogen degradation by BmCL1 occurs by the hydrolysis of Aα- and Bβ-chains, generating products similar to those produced by fibrinogenolytic cathepsins from other organisms. In conclusion, BmCL1 likely has an additional role in R. microplus blood digestion, besides its role in hemoglobin degradation at acid pH. BmCL1 fibrinogenolytic activity indicates a proteolytic activity in the neutral lumen of tick midgut, contributing to maintain the fluidity of the ingested blood, which remains to be confirmed in vivo.

  • expression profile of Rhipicephalus microplus vitellogenin receptor during oogenesis
    Ticks and Tick-borne Diseases, 2018
    Co-Authors: Adriana Seixas, Antônio F.m. Pinto, Mara Fernanda A Alzugaray, Lucas Tirloni, Luis Fernando Parizi, Naftaly Wangâombe Githaka, Satoru Konnai, Kazuhiko Ohashi, John R Yates
    Abstract:

    The vitellogenin receptor (VgR), which belongs to the low-density lipoprotein receptors (LDLR) family, regulates the absorption of yolk protein accumulated in developing oocytes during oogenesis. In the present study, the full sequence of Rhipicephalus microplus VgR (RmVgR) and the partial sequence of Rhipicephalus appendiculatus VgR (RaVgR) ORF were determined and cloned. The RmVgR amino acid sequence contains the five highly conserved structural motifs characteristic of LDLR superfamily members, the same overall structure as observed in other species. Phylogenetic analysis separated VgRs in two major groups, corresponding to receptors from acarines and insects. Consistent with observations from other arthropods, RmVgR was specifically expressed in the ovarian tissue and its peak of expression occurs in females that are detaching from the host. Silencing with RmVgR dsRNA reduced VgR expression, which resulted in reduced fertility, evidenced by a decrease in the number of larvae. The present study confirms RmVgR is a specific receptor involved in yolk protein uptake and oocyte maturation in R. microplus, playing an important role in tick reproduction.

  • Differential immunoproteomics enables identification of Metarhizium anisopliae proteins related to Rhipicephalus microplus infection
    Research in Microbiology, 2009
    Co-Authors: Lucélia Santi, Augusto Schrank, Walter Orlando Beys Da Silva, Antônio F.m. Pinto, Marilene Henning Vainstein
    Abstract:

    Abstract Differential immunoproteomics was applied to identify proteins secreted by Metarhizium anisopliae induced by the Rhipicephalus microplus cuticle. In addition, IgG anti-spore surface proteins were used for searching for proteins possibly involved in early stages of fungus versus tick infection. LC-MS/MS of differentially secreted proteins led to the identification of proteases (carboxypeptidase and Pr1A), chitinase, carboxylic acid transport and proline-rich protein. Differential immunoproteomics strategy facilitated the detection and the identification of new proteins related to M. anisopliae host–pathogen interaction and could be used in further works to identify novel proteins related to other microbial infection systems.

Adriana Seixas - One of the best experts on this subject based on the ideXlab platform.

  • blood anticlotting activity of a Rhipicephalus microplus cathepsin l like enzyme
    Biochimie, 2019
    Co-Authors: Marina Amaral Xavier, Ricardo J.s. Torquato, Adriana Seixas, Itabajara Da Silva Vaz, Antônio F.m. Pinto, Lucas Tirloni, John R Yates, Aparecida Tanaka, Jolene K Diedrich, Carlos Termignoni
    Abstract:

    Abstract In parasites, cathepsins are implicated in mechanisms related to organism surveillance and host evasion. Some parasite cathepsins have fibrinogenolytic and fibrinolytic activity, suggesting that they may contribute to maintain blood meal fluidity for extended feeding periods. Here, it is shown that BmGTI (Rhipicephalus [Boophilus] microplus Gut Thrombin Inhibitor), a protein previously described as an inhibitor of fibrinogen hydrolysis and platelet aggregation by thrombin, and BmCL1 (Rhipicephalus [Boophilus] microplus Cathepsin-L like 1) are the same protein, hereinafter referred to using the earliest name (BmCL1). To further characterize BmCL1, Rhipicephalus microplus native and recombinant (rBmCL1) proteins were obtained. Native BmCL1 was isolated using thrombin-affinity chromatography, and it displays thrombin inhibition activity. We subsequently investigated rBmCL1 interaction with thrombin. We show that rBmCL1 and thrombin have a dissociation constant (ΚD) of 130.2 ± 11.2 nM, and this interaction likely occurs due to a more electronegative surface of BmCL1 at pH 7.5 than at pH 5.0, which may favor an electrostatic binding to positively charged thrombin exosites. During BmCL1-thrombin interaction, thrombin is not degraded or inhibited. rBmCL1 impairs thrombin-induced fibrinogen clotting via a fibrinogenolytic activity. Fibrinogen degradation by BmCL1 occurs by the hydrolysis of Aα- and Bβ-chains, generating products similar to those produced by fibrinogenolytic cathepsins from other organisms. In conclusion, BmCL1 likely has an additional role in R. microplus blood digestion, besides its role in hemoglobin degradation at acid pH. BmCL1 fibrinogenolytic activity indicates a proteolytic activity in the neutral lumen of tick midgut, contributing to maintain the fluidity of the ingested blood, which remains to be confirmed in vivo.

  • expression profile of Rhipicephalus microplus vitellogenin receptor during oogenesis
    Ticks and Tick-borne Diseases, 2018
    Co-Authors: Adriana Seixas, Antônio F.m. Pinto, Mara Fernanda A Alzugaray, Lucas Tirloni, Luis Fernando Parizi, Naftaly Wangâombe Githaka, Satoru Konnai, Kazuhiko Ohashi, John R Yates
    Abstract:

    The vitellogenin receptor (VgR), which belongs to the low-density lipoprotein receptors (LDLR) family, regulates the absorption of yolk protein accumulated in developing oocytes during oogenesis. In the present study, the full sequence of Rhipicephalus microplus VgR (RmVgR) and the partial sequence of Rhipicephalus appendiculatus VgR (RaVgR) ORF were determined and cloned. The RmVgR amino acid sequence contains the five highly conserved structural motifs characteristic of LDLR superfamily members, the same overall structure as observed in other species. Phylogenetic analysis separated VgRs in two major groups, corresponding to receptors from acarines and insects. Consistent with observations from other arthropods, RmVgR was specifically expressed in the ovarian tissue and its peak of expression occurs in females that are detaching from the host. Silencing with RmVgR dsRNA reduced VgR expression, which resulted in reduced fertility, evidenced by a decrease in the number of larvae. The present study confirms RmVgR is a specific receptor involved in yolk protein uptake and oocyte maturation in R. microplus, playing an important role in tick reproduction.

  • Molecular and functional characterization of Bm05br antigen from Rhipicephalus microplus
    Ticks and Tick-borne Diseases, 2016
    Co-Authors: Maria Fernanda Alzugaray, Adriana Seixas, Luis Fernando Parizi, Uruguaysito Benavides, Itabajara Da Silva Vaz
    Abstract:

    Abstract Rhipicephalus microplus is a cattle-specific tick, causing considerable losses in the livestock industry. The identification of molecules responsible for modulation of host defenses during different parasite stages can help in the development of alternative methods, such as vaccination, to control tick infestations. Hq05, a protein of unknown function identified in the tick Haemaphysalis qinghaiensis, induced a significant protective immune response when used as a vaccine in sheep. In the present study, we investigated Bm05br, the Hq05 homologous gene from R. microplus . Besides H. qinghaiensis , Bm05br homologous found in other tick species such as Rhipicephalus annulatus , Rhipicephalus sanguineus sensu lato, Haemaphysalis longicornis and Ixodes scapularis were comparatively analyzed. Bm05br expression profile in different R. microplus tissues and life-stages was determined by qRT-PCR and Western blot. Bm05br was detected in ovaries, salivary glands and the fat body of both partially and fully engorged females. The highest transcription levels were observed in partially engorged females fat body and salivary glands. Gene knockdown by RNAi reduced egg hatching rate and the weight of tick larvae obtained from treated group, when compared to controls. These results indicate that Bm05br may be involved in R. microplus reproduction. Together with its distribution and high sequence conservation across different tick species, our data suggest Bm05br as a potential antigen for development of a multispecies anti-tick vaccine.

  • Rhipicephalus microplus and Ixodes ovatus cystatins in tick blood digestion and evasion of host immune response
    Parasites & Vectors, 2015
    Co-Authors: Luis Fernando Parizi, Aoi Masuda, Adriana Seixas, Satoru Konnai, Kazuhiko Ohashi, Gabriela Alves Sabadin, Maria Fernanda Alzugaray, Carlos Logullo, Itabajara Da Silva Vaz
    Abstract:

    Background Cystatins are a group of cysteine protease inhibitors responsible for physiological proteolysis regulation and present in a wide range of organisms. Studies about this class of inhibitors in parasites have contributed to clarify their roles in important physiological processes, like blood digestion and modulation of host immune response during blood feeding. Thus, cystatins are a subject of research on the development of new parasite control methods. Additionally, the characterization of proteins shared by different parasite species represents a valuable strategy to find potential targets in multi-species control methods. However, cystatin functions in ticks remain undetermined, especially in Rhipicephalus microplus and Ixodes ovatus, two species that affect livestock and human health, respectively.

  • tissue expression and the host s immunological recognition of a Rhipicephalus microplus paramyosin
    Veterinary Parasitology, 2013
    Co-Authors: Bruna Ferreira Leal, Aoi Masuda, Adriana Seixas, Roberta T Mattos, Mariana Loner Coutinho, Itabajara Da Silva Vaz, Carlos Ferreira
    Abstract:

    Abstract Rhipicephalus microplus is a parasite that causes economic losses in cattle herds, and immunological control is the most promising alternative to replace chemical control. The muscular protein paramyosin has been additionally found in non-muscle tissues and characterized as presenting activities that enable the evasion of the host's immune system in various parasites. This report investigated the recognition level of paramyosin by sera of infested bovines, its expression in tissues, organs and different life stages of R. microplus. ELISA analyses showed that paramyosin and salivary gland extract were recognized by infested Bos taurus and B. indicus sera. Paramyosin gene expression was evaluated in egg, larvae, adult male, and several tissues of partially- and fully-engorged females by qRT-PCR, showing the highest expression levels in fat body. These results show that R. microplus paramyosin is immunologically recognized during the tick infestation and together with the high transcription rate found in organs that do not present a highly developed musculature, further suggests that it may possess additional, non-muscle functions in the tick-bovine relationship.

Teresinha Tizu Sato Schumaker - One of the best experts on this subject based on the ideXlab platform.

  • applicability of in vitro bioassays for the diagnosis of ivermectin resistance in Rhipicephalus microplus acari ixodidae
    Veterinary Parasitology, 2012
    Co-Authors: Guilherme Marcondes Klafke, Eleonor Adega Castrojaner, Marcia Cristina Mendes, A Namindome, Teresinha Tizu Sato Schumaker
    Abstract:

    Abstract The applicability of laboratory bioassays to diagnose ivermectin (IVM) resistance in Rhipicephalus microplus was evaluated. Adult immersion tests (AITs), larval immersion tests (LITs) and larval packet tests (LPTs) were performed to characterise the effects of ivermectin toxicity on adults and larvae of a susceptible reference strain. The AIT was determined to be a reasonable assay but requires a large number of individuals to attain interpretable results. The LIT and LPT were validated with an IVM resistant strain, revealing resistance ratios (RRs) of 6.73 and 1.49, respectively. In a field survey, nine different populations of cattle tick from the states of Sao Paulo and Mato Grosso do Sul, Brazil, were analysed with the LIT. Populations without previous exposure to ivermectin exhibited RRs between 0.87 and 1.01. Populations previously exposed to IVM showed RRs between 1.83 and 4.62. The LIT was more effective at discriminating between resistant and susceptible populations than the LPT. The use of the LIT is recommended for the diagnosis of ivermectin resistance in R. microplus.

  • Selection of an ivermectin-resistant strain of Rhipicephalus microplus (Acari: Ixodidae) in Brazil.
    Veterinary parasitology, 2009
    Co-Authors: Guilherme Marcondes Klafke, Thais Aguiar De Albuquerque, Robert John Miller, Teresinha Tizu Sato Schumaker
    Abstract:

    Resistance to ivermectin (IVM) in field populations of Rhipicephalus microplus of Brazil has been observed since 2001. In this work, four selection methods (infestations with: (1) IVM-treated larvae; (2) larvae from IVM-treated adult female ticks; (3) larvae from IVM-treated adult female ticks on an IVM-treated host; and (4) larvae obtained from IVM-treated females that produced eggs with a high eclosion rate) were used on a field population with an initial ivermectin (IVM) resistance ratio at LC50 (RR50) of 1.37 with the objective to obtain experimentally a highly-resistant strain. After ten generations, using these methods combined, the final RR50 was 8.06. This work shows for the first time that it was possible to increase IVM resistance in R. microplus in laboratory conditions. The establishment of a drug resistant R. microplus strain is a fundamental first step for further research into the mechanisms of ivermectin-resistance in R. microplus and potentially methods to control this resistance.