Publications by authors named "Guilherme Rocha Lino de Souza"

8 Publications

  • Page 1 of 1

Larvicidal potential of cell wall degrading enzymes from Trichoderma asperellum against Aedes aegypti (Diptera: Culicidae).

Biotechnol Prog 2021 Jun 11:e3182. Epub 2021 Jun 11.

Laboratório de Química de Polímeros (LQP) - ICB2, Universidade Federal de Goiás, Goiânia, Brazil.

Aedes aegypti is a mosquito vector of arboviruses such as dengue, chikungunya, zika and yellow fever that cause important public health diseases. The incidence and gravity of these diseases justifies the search for effective measures to reduce the presence of this vector in the environment. Bioinsecticides are an effective alternative method for insect control, with added ecological benefits such as biodegradability. The current study demonstrates that a chitinolytic enzyme complex produced by the fungus Trichoderma asperellum can disrupt cuticle formation in the L3 larvae phase of A. aegypti, suggesting such biolarvicidal action could be used for mosquito control. T. asperellum was exposed to chitin from different sources. This induction of cell wall degrading enzymes, including chitinase, N-acetylglucosaminidase and β-1,3-glucanase. Groups of 20 L3 larvae of A. aegypti were exposed to varying concentrations of chitinolytic enzymes induced with commercial chitin (CWDE) and larvae cell wall degrading enzymes (L-CWDE). After 72 h of exposure to the CWDE, 100% of larvae were killed. The same percent mortality was observed after 48 h of exposure to L-CWDE at half the CWDE enzyme mixture concentration. Exoskeleton deterioration was further observed by scanning and electron microscopy. Our findings indicate that L-CWDE produced by T. asperellum reflect chitinolytic enzymes with greater specificity for L3 larval biomolecules. This specificity is characterized by the high percentage of mortality compared with CWDE treatments and also by abrupt changes in patterns of the cellular structures visualized by scanning and transmission electron microscopy. These mixtures of chitinolytic enzymes could be candidates, as adjuvant or synergistic molecules, to replace conventional chemical insecticides currently in use.
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http://dx.doi.org/10.1002/btpr.3182DOI Listing
June 2021

An update on amitraz efficacy against Rhipicephalus microplus after 15 years of disuse.

Parasitol Res 2021 Mar 25;120(3):1103-1108. Epub 2021 Jan 25.

Escola de Veterinária e Zootecnia, Universidade Federal de Goiás, Goiânia, Goiás, Brazil.

Amitraz is an acaricide that is widely used in veterinary medicine to control the cattle tick Rhipicephalus microplus. However, controversy exists in the literature regarding the resistance of R. microplus to this product. The present work provides an update on the acaricidal efficacy of amitraz (Triatox®, 12.5 % amitraz) after 15 years without its use on a property. Two in vivo (bovines treated with amitraz and submitted to tick counts, n = 20 animals) and one in vitro (adult immersion test, n = 40 ticks) assays were performed to determine product efficacy. The efficacy of the commercial formulation tested in the first in vivo trial ranged from 14.1 to 47.0%, and in the second from 3.6 to 35.1%, for the 28 days of the experiments. Efficacy for the in vitro trial was 47.38%. The dose recommended by the manufacturer of the product did not cause mortality to most of the ticks of this strain, and efficacy/resistance was not reverted or modified after 15 years (estimated 60 tick generations).
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http://dx.doi.org/10.1007/s00436-021-07063-5DOI Listing
March 2021

Immunoconjugates to increase photoinactivation of bovine alphaherpesvirus 1 in semen.

Vet Microbiol 2020 Aug 1;247:108780. Epub 2020 Jul 1.

Escola de Veterinária e Zootecnia, Universidade Federal de Goiás, Campus Samambaia, Avenida Esperança, s/n, Campus Universitário, 74690-900, Goiânia, GO, Brazil; Departamento de Bioquímica e Biologia Molecular, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Campus Samambaia, Avenida Esperança, s/n, Campus Universitário, 74690-900, Goiânia, GO, Brazil. Electronic address:

Artificial insemination and in vitro embryo production are increasingly used to improve the reproductive efficiency of herds, however success of these techniques depends on the sanitary quality of the semen. Insemination centers commonly use antibiotics in their routine procedure, but they are not able against viruses. In this paper, we demonstrate a new approach for disinfecting virus in bovine semen using photoimmunoinactivation, an adaptation of the photodynamic inactivation (PDI) methodology. The photosensitizers (PSs), hematoporphyrin (HP) and zinc tetracarboxy-phthalocyanine (ZnPc) were conjugated to Immunoglobulin Y (IgY) anti-bovine alphaherpesvirus 1 (BoHV-1) and used for PDI against the BoHV-1 viruses in cell culture and compared to the unconjugated PSs. Both treatments proved to be efficient, but a significant decrease in the irradiation time required to completely eliminate the virus was observed in the samples treated with the immunoconjugates. Photophysical measurements help us to understand the coupling between PSs and IgY and the evaluated production of singlet oxygen. Following the cell culture test, the same approach was applied in semen artificially infected with BoHV-1. The immunoconjugates were also efficient for complete virus inactivation up to 5 min of irradiation and proved to be safe using several parameters of sperm viability, demonstrating the feasibility of our strategy for disinfection viruses in semen.
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http://dx.doi.org/10.1016/j.vetmic.2020.108780DOI Listing
August 2020

Development of a nanogold slot blot inhibition assay for the detection of antibodies against bovine herpesvirus type 1.

Arch Virol 2018 Jun 21;163(6):1549-1557. Epub 2018 Feb 21.

Programa de Pós-graduação em Ciência Animal, Escola de Veterinária e Zootecnia (PPGCA/EVZ), Universidade Federal de Goiás, Goiânia, GO, Brazil.

Bovine herpesvirus type 1 (BoHV-1) is recognized as an important pathogen causing respiratory, reproductive, and neurological disorders in cattle and is associated with economic losses to animal industry. Accurate diagnostic methods are needed for prevention of disease transmission. While the virus neutralization test is considered the gold standard method, it requires maintenance of the virus and cell cultures, which is time consuming and expensive. Serological techniques such as enzyme-linked immunosorbent assay (ELISA) are widely applied, as these are easy to perform and provide quick results. In the present study, a nanogold slot blot inhibition assay was developed for the serological diagnosis of BoHV-1 and compared with standard ELISA and horseradish peroxidase (HRP) slot blot assays. Of 42 serum samples tested by ELISA, 32 (76.2%) were positive and 10 (23.8%), were negative. The sensitivity and specificity of the nanogold slot blot inhibition assay was similar to that observed for ELISA and HRP slot blot assays, and a strong correlation was observed between the tests. Thus, the nanogold slot blot inhibition assay may serve as an efficient and rapid alternative to ELISA in settings, where plate-reading equipment is lacking.
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http://dx.doi.org/10.1007/s00705-018-3763-4DOI Listing
June 2018

Cutaneous hypersensitivity test to evaluate phage display anti-tick borne vaccine antigen candidates.

Exp Parasitol 2011 Dec 12;129(4):388-92. Epub 2011 Sep 12.

Laboratório de Nanobiotecnologia, Instituto de Genética e Bioquímica, Universidade Federal de Uberlândia-UFU, Campus Umuarama 2E-248, 38400-902 Uberlândia, MG, Brazil.

Early experiments performed by our group with the phage display technique revealed the potential for using epitope-displaying phages (mimotopes) as a tool for tick antigen discovery. Thus, as a preliminary study, inflammatory reactions induced by phage display tick-borne candidates were investigated by using the cutaneous hypersensitivity test. The profile of selected Rhipicephalus microplus mimotopes was assessed on tick field-exposed cattle and our data indicated a pattern similar to immediate hypersensitivity reaction and not a delayed immune response as expected. However, the wild-type phage inoculation surprisingly induced a strong immediate response on its own. Such reactions indicate that the wild-type phage may have hidden many of the potential reactions raised by the mimotopes. The study of the inflammatory reactions to these phage mimotopes in tick-infested hosts may provide basic information about the immune reaction. Finally, this work is of relevance for when considering research alternatives for finding and characterization of antigens by the phage display technique.
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http://dx.doi.org/10.1016/j.exppara.2011.08.017DOI Listing
December 2011

In silico analysis for identification of tick phagotopes selected by phage-displayed libraries.

Rev Bras Parasitol Vet 2009 Jan-Mar;18(1):39-41

Laboratório de Bionanotecnologia, Instituto de Genética e Bioquímica, Universidade Federal de Uberlândia--UFU, Brazil.

Phage display techniques have been widely employed to map epitope structures which have served as the basis for developing molecular vaccines. We have applied this technique to map specific epitopes of Rhipicephalus (Boophilus) microplus. In the present study, we have identified the potential immunogens using a process in which the selected phage clones were analyzed through bioinformatics, prior to final field tests. The present study demonstrates the feasibility of identifying important R. (B.) microplus phagotopes for vaccine development through screening of phage-displayed random peptide libraries and bioinformatics tools.
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October 2009

Esterase enzymes involved in pyrethroid and organophosphate resistance in a Brazilian population of Riphicephallus (Boophilus) microplus (Acari, Ixodidae).

Mol Biochem Parasitol 2008 Jul 7;160(1):70-3. Epub 2008 Apr 7.

Universidade Federal de Uberlândia, Instituto de Genética e Bioquímica, Laboratório de Genética, Campus Umuarama, Uberlândia, MG, Brazil.

Esterases are a group of enzymes that are reportedly associated with acaricide resistance in Riphicephallus (Boophilus) microplus. A comparative analysis was made of the esterase patterns in malathion and deltamethrin-sensitive, tolerant and resistant tick groups, using non-denaturing polyacrylamide gel electrophoresis. Electrophoretical profiles revealed four bands of esterase activity against alpha-naphthyl acetate; which were dubbed EST-1 to EST-4. The EST-3 and EST-4 were detected in all strains and were classified as carboxylesterases (CaEs). The EST-2, classified as an acetylcholinesterase (AChE), was detected in all groups, but its staining intensity increased from susceptible to resistant groups, indicating an altered production according to the degree of resistance. EST-1, which was also classified as an AChE, was detected exclusively in tolerant and resistant groups to both acaricides, but displayed greater activity in the malathion-resistant group. These data suggest that these AChEs may represent an important detoxification strategy developed to overcome the effects of acaricides.
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http://dx.doi.org/10.1016/j.molbiopara.2008.03.009DOI Listing
July 2008

Identification of point mutations in a putative carboxylesterase and their association with acaricide resistance in Rhipicephalus (Boophilus) microplus (Acari: Ixodidae).

Vet Parasitol 2007 Sep 23;148(3-4):301-9. Epub 2007 Jul 23.

Universidade Estadual de Londrina, Departamento de Biologia Geral, Laboratório de Genética Molecular, Rodovia Celso Garcia Cid (PR445), Km 380, CEP 86051-990, Caixa Postal 6001, Londrina, PR, Brazil.

Chemical control based on the use of pyrethroid and organophosphate compounds has selected resistant genotypes in populations of Rhipicephalus (Boophilus) microplus. Point mutations in esterase-encoding genes represent one of the main resistance mechanisms in this species. In this study, the PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) technique was used to investigate the presence of mutations in a fragment of a putative carboxylesterase in a population of ticks with a history of resistance. The digestion of a fragment of 372 pb with EcoRI revealed three genotypes: W, H and M, observed in different frequencies. The homozygous wild-type genotype (W) was detected only in sensitive strains, with high frequency. The heterozygous genotype (H) was observed in all the strains, albeit with higher frequency in the strains with a moderate resistance, while the homozygous mutant genotype (M) was found only in the moderate resistant strain and resistant strains, with higher frequency in the resistant strains. A comparison of the sequences indicated the presence of other mutations, besides EcoRI polymorphism in the moderate resistant and resistant strains. Also found was the presence of stop codons generating truncated proteins in the sensitive and moderate resistant strains. A domain analysis revealed the presence of additional domains in the resistant strain. These findings suggest that different point mutations, as well as the influence of post-translational modification mechanisms, are altering the activity of the translated proteins and may be associated with resistance.
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http://dx.doi.org/10.1016/j.vetpar.2007.06.016DOI Listing
September 2007
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