Papers by Renato L Santos
Veterinary Parasitology, 2008
Visceral leishmaniasis (VL) is endemic in Belo Horizonte (State of Minas Gerais, Brazil). Leishma... more Visceral leishmaniasis (VL) is endemic in Belo Horizonte (State of Minas Gerais, Brazil). Leishmania sp. can naturally infect several species of mammals, and the domestic dog is the most important reservoir of the disease in South America. This report describes five cases of visceral leishmaniasis in Brazilian canids. Among 15 animals kept in captivity in a zoo in Belo Horizonte (State of Minas Gerais, Brazil), two animals, a bush dog (Spheotos venaticos) and a hoary zorro (Lycalopex vetulus) were serologically positive and developed clinical signs of VL, whereas three other canids, including a crab-eating fox (Cerdocyon thous), a maned wolf (Chrysocyon brachyurus), and a hoary zorro (Lycalopex vetulus) had positive serological results without clinical signs. #
Emerging Infectious Diseases, 2009
Veterinary Microbiology, 2003
Salmonella enterica serovar Typhimurium is an important cause of enteric infections in farm anima... more Salmonella enterica serovar Typhimurium is an important cause of enteric infections in farm animals and it is one of the most frequent food borne infections worldwide. Serovar Typhimurium lacking the sopB gene is attenuated for induction of host inflammatory response and fluid accumulation into the intestinal lumen, which correlates with clinical diarrhea. SopB is an inositol phosphate phosphatase, but its exact role in the pathogenesis of salmonellosis is still unclear. We employed the bovine ileal ligated loop model to compare the tissue distribution of a sopB mutant and its wild type parent serovar Typhimurium. Sections of the Peyer's patches were histologically processed and immuno-stained for detection of serovar Typhimurium. In addition, samples were processed for transmission electron microscopy, and the profile of expression of host chemokine and cytokine responses was assessed. Ultrastructurally both strains had the same ability to invade intestinal epithelial cells. No differences were detected in the tissue distribution of the sopB mutant and the wild type organism and both strains elicited the same profile of chemokines and pro-inflammatory cytokines. In conclusion, our results indicate that the attenuation of the sopB mutant is associated with pathogenic mechanisms other than invasion and distribution in host intestinal tissues.
The Veterinary Journal, 2010
Brucellosis is one of the most important zoonotic diseases worldwide, resulting in serious econom... more Brucellosis is one of the most important zoonotic diseases worldwide, resulting in serious economic losses and public health issues. It is caused by intracellular Gram-negative bacteria of the genus Brucella, which are responsible for a debilitating disease in humans and a chronic infection in domestic animals. The present article considers the pathogenesis of Brucella spp., with the goal to cover clinical aspects of the disease in the different mammalian species along with the target cells used by this pathogen to survive inside the host. Additionally, important molecular mechanisms used by Brucella to invade and persist inside the hosts target cells are also discussed.
Arquivo Brasileiro de Medicina Veterinária e Zootecnia, 2004
Avaliou-se a influência do fechamento parcial do anel inguinal externo (AIE) na morfologia testic... more Avaliou-se a influência do fechamento parcial do anel inguinal externo (AIE) na morfologia testicular e caracterizaram-se as alterações pós-operatórias decorrentes de sua utilização em seis eqüinos machos. Sob anestesia geral, criou-se um acesso à cavidade vaginal que foi seguido de síntese da túnica vaginal parietal e sutura do AIE ipsilateral em aproximadamente 75% de seu diâmetro (antímero suturado). No antímero contralateral foi realizado procedimento cirúrgico semelhante, mas a sutura do anel inguinal foi removida imediatamente após sua aplicação (antímero controle). No pós-operatório, os animais foram examinados diariamente por quatro semanas. O trauma cirúrgico acarretou degeneração testicular no período pós-operatório e o acesso à cavidade vaginal predispôs à formação de aderências testiculares. O grau de degeneração testicular foi equivalente nos dois antímeros, suturado e controle, e nenhum dos testículos apresentou degeneração. O procedimento mostrou ser uma alternativa viável para o tratamento de hérnias inguinais quando se deseja evitar a orquiectomia.
American journal of veterinary research, 2002
To evaluate hematologic and serum biochemical changes in Salmonella ser Typhimurium-infected calv... more To evaluate hematologic and serum biochemical changes in Salmonella ser Typhimurium-infected calves. 16 male 3- to 4-week-old dairy calves. 13 calves were experimentally infected with S Typhimurium (strains IR715 and CS401, which are derivatives of ATCC 14028), and 3 calves were uninfected controls. Several hematologic and serum biochemical parameters were measured. Hematologic changes included increases in PCV, RBC count, and hemoglobin concentration, associated with a transitory leukopenia characterized by neutropenia and lymphopenia. Biochemical findings included hypoglycemia, increased BUN, creatinine, and fibrinogen concentrations, and decreased sodium, total CO2, calcium, total protein, and albumin concentrations. Increased total bilirubin concentration associated with decreased conjugated bilirubin concentration was also observed. No significant changes in aspartate aminotransferase, gamma-glutamyltranspeptidase, alkaline phosphatase, and creatinine kinase activities were det...
Molecular Medical Microbiology, 2015
Frontiers in Immunology, 2014
Arquivo Brasileiro De Medicina Veterinaria E Zootecnia, 2000
ABSTRACT
Memorias Do Instituto Oswaldo Cruz, 2005
The yield as well as phenotypic and functional parameters of canine peripheral blood monocyte-der... more The yield as well as phenotypic and functional parameters of canine peripheral blood monocyte-derived macrophages were analyzed. The cells that remained adherent to Teflon after 10 days of culture had high phagocytic activity when inoculated with Leishmania chagasi. Flow cytometric analysis demonstrated that more than 80% of cultured cells were positive for the monocyte/macrophage marker CD14.
PLoS pathogens, 2014
Delivery of microbial products into the mammalian cell cytosol by bacterial secretion systems is ... more Delivery of microbial products into the mammalian cell cytosol by bacterial secretion systems is a strong stimulus for triggering pro-inflammatory host responses. Here we show that Salmonella enterica serovar Typhi (S. Typhi), the causative agent of typhoid fever, tightly regulates expression of the invasion-associated type III secretion system (T3SS-1) and thus fails to activate these innate immune signaling pathways. The S. Typhi regulatory protein TviA rapidly repressed T3SS-1 expression, thereby preventing RAC1-dependent, RIP2-dependent activation of NF-κB in epithelial cells. Heterologous expression of TviA in S. enterica serovar Typhimurium (S. Typhimurium) suppressed T3SS-1-dependent inflammatory responses generated early after infection in animal models of gastroenteritis. These results suggest that S. Typhi reduces intestinal inflammation by limiting the induction of pathogen-induced processes through regulation of virulence gene expression.
Comparative Immunology, Microbiology and Infectious Diseases, 2014
Brucellosis, a worldwide zoonosis, is linked to reproductive problems in primary hosts. A high pr... more Brucellosis, a worldwide zoonosis, is linked to reproductive problems in primary hosts. A high proportion of Brucella-positive hooded seals (Cystophora cristata) have been detected in the declined Northeast Atlantic stock. High concentrations of polychlorinated biphenyls (PCBs) have also been discovered in top predators in the Arctic, including the hooded seal, PCB 153 being most abundant. The aim of this study was to assess the pathogenicity of Brucella pinnipedialis hooded seal strain in the mouse model and to evaluate the outcome of Brucella spp. infection after exposure of mice to PCB 153. BALB/c mice were infected with B. pinnipedialis hooded seal strain or Brucella suis 1330, and half from each group was exposed to PCB 153 through the diet. B. pinnipedialis showed a reduced pathogenicity in the mouse model as compared to B. suis 1330. Exposure to PCB 153 affected neither the immunological parameters, nor the outcome of the infection. Altogether this indicates that it is unlikely that B. pinnipedialis contribute to the decline of hooded seals in the Northeast Atlantic.
Ciência Rural, 2007
A 22 year-old horse developed cholelithiasis with marked atrophy of the right lateral hepatic lob... more A 22 year-old horse developed cholelithiasis with marked atrophy of the right lateral hepatic lobe. The horse had a history of intermittent colic since three years of age, and one of the first episodes of colic was associated with icterus. The size of the right lateral hepatic lobe was extremely reduced. There was a large choledocholith in the common hepatic duct, and several hepatoliths and choleliths in the intra-and extra-hepatic billiary ducts. Microscopically, there was severe atrophy of the right lobe with diffuse proliferation of connective tissue and billiary ducts. The left lateral lobe had peri-portal fibrosis with proliferation of billiary ducts, and billiary stasis. Chemical analysis of the calculi detected amorphous and triple phosphate, bilirubin, calcium, and iron.
Ciência Rural, 2009
Arcanobacterium pyogenes, Bovine Herpesvirus 1, Brucella abortus, Campylobacter fetus subsp. vene... more Arcanobacterium pyogenes, Bovine Herpesvirus 1, Brucella abortus, Campylobacter fetus subsp. venerealis, Chlamydophila abortus, Leptospira sp., Listeria monocytogenes, Salmonella sp., Mycoplasma bovis, Mycoplasma bovigenitalium, Neospora caninum, and Tritrichomonas foetus. Tissue homogenates from 42 fetuses and paraffin-embedded tissues from 28 fetuses and 14 placentas/endometrium were included in this study. Brucella abortus was detected in 14.2% (12/84) of the samples. Salmonella sp. DNA was amplified from 2 fetuses, and there was one positive for Neospora caninum, and another for Listeria monocytogenes. This PCR-based approach resulted in identification of the etiology in 19% of samples, or 20% if considered fetal tissues only. RESUMO Aborto infeccioso é uma causa significativa de falhas reprodutivas e perdas econômicas na bovinocultura. O objetivo deste estudo foi detectar ácidos nucleicos de vários agentes infecciosos reconhecidos como causadores de aborto, incluindo-se Arcanobacterium pyogenes, Herpesvirus bovino tipo 1, Brucella abortus, Campylobacter fetus subsp. venerealis, Chlamydophila abortus, Leptospira sp., Listeria monocytogenes, Salmonella sp., Mycoplasma bovis, Mycoplasma bovigenitalium, Neospora caninum e Tritrichomonas foetus. Homogenados de tecidos de 42 fetos e tecidos incluídos em parafina de 28 fetos e 14 placentas/ endométrio foram incluídos neste estudo. Brucella abortus foi detectada em 14,2% (12/84) das amostras. DNA de Salmonella sp. foi amplificado de dois fetos e houve um feto positivo para Neospora caninum e outro para Listeria monocytogenes. Essa metodologia baseada em PCR resultou na identificação da etiologia em 19% das amostras ou 20% se considerados somente os tecidos fetais.
Infection with bacteria of the genus Brucella results in major economic and political impact by c... more Infection with bacteria of the genus Brucella results in major economic and political impact by causing reproductive diseases in a significant number of domestic animal species. Moreover, it has a great social significance, since many species are capable of causing human infection, with severe consequences. Dissemination of knowledge on a specific disease is an essential step for its control. Considering that brucellosis is still the most prevalent zoonosis in the world, information about taxonomy, clinical signs in domestic animals and humans are crucial for attempting to reduce the prevalence of this disease. The recent isolation and characterization of nonclassical species of Brucella indicates that a lot remains to be discovered about this genus. Nevertheless, due to the socialeconomic importance of brucellosis, this review aims to clarify points related to taxonomy of the genus and describe the clinical relevance of infection in humans and domestic animals. Key word: Brucellosis, Brucella, taxonomy. RESUMO A infecção por bactérias do gênero Brucella apresenta grande importância econômica e política por causar doenças com impacto reprodutivo em um número significativo de espécies de animais domésticos. Além disso, possui grande importância social, já que várias espécies são capazes de causar infecção humana, com graves consequências. A difusão do conhecimento em relação a uma determinada doença é um passo essencial para o seu controle. Considerando-se que a brucelose ainda é a zoonose mais prevalente no mundo, informações sobre a taxonomia, os principais sinais clínicos nas diferentes espécies domésticas e os diferentes aspectos da doença humana são de importância crucial para a tentativa de diminuir a prevalência dessa enfermidade. O recente isolamento e a caracterização de espécies não clássicas de Brucella demonstram que ainda há muito a ser descoberto sobre esse gênero. Tendo em vista a importância socioeconômica da infecção por Brucella spp., esta revisão tem como objetivos esclarecer pontos relacionados à taxonomia do gênero, bem como descrever aspectos clínicos relevantes na infecção humana e nas diferentes espécies domésticas. Palavras-chave: Brucelose, Brucella, taxonomia.
PloS one, 2014
Brucella ovis is a major cause of reproductive failure in rams and it is one of the few well-desc... more Brucella ovis is a major cause of reproductive failure in rams and it is one of the few well-described Brucella species that is not zoonotic. Previous work showed that a B. ovis mutant lacking a species-specific ABC transporter (ΔabcBA) was attenuated in mice and was unable to survive in macrophages. The aim of this study was to evaluate the role of this ABC transporter during intracellular survival of B. ovis. In HeLa cells, B. ovis WT was able to survive and replicate at later time point (48 hpi), whereas an ΔabcBA mutant was attenuated at 24 hpi. The reduced survival of the ΔabcBA mutant was associated with a decreased ability to exclude the lysosomal marker LAMP1 from its vacuolar membrane, suggesting a failure to establish a replicative niche. The ΔabcBA mutant showed a reduced abundance of the Type IV secretion system (T4SS) proteins VirB8 and VirB11 in both rich and acid media, when compared to WT B. ovis. However, mRNA levels of virB1, virB8, hutC, and vjbR were similar in b...
The Scientific World Journal, 2014
Infectious epididymitis is considered a major cause of economic losses for the sheep industry wor... more Infectious epididymitis is considered a major cause of economic losses for the sheep industry worldwide. This study aimed to investigate clinical and pathological changes associated with experimental infections with A. seminis and H. somni in rams. Twenty rams of age 18 to 24 months were infected by intraepididymal inoculation of A. seminis ( = 10) and H. somni ( = 10). Rams were weekly examined and biological samples were collected during six weeks. All rams inoculated with A. seminis and 80% inoculated with H. somni became infected. The recovery of bacteria was possible in semen and urine samples and tissues in both experimental groups. Clinically, there were a decrease in testicular consistency and an increase in measures of the left epididymis tails in both experimental groups. The main gross changes were observed in the reproductive tract. Microscopically, the main lesions were inflammatory changes in the genitourinary tract and testicular degeneration. A. seminis and H. somni were able to colonize several organs of the genitourinary tract in rams, being indistinguishable by clinical exam, necropsy or histopathology. For differential diagnosis, it is important to use diagnostic techniques for direct confirmation of the etiologic agent.
FEMS Microbiology Letters, 2002
Epidemiological evidence shows that the sopE1 gene is associated with Salmonella Typhimurium phag... more Epidemiological evidence shows that the sopE1 gene is associated with Salmonella Typhimurium phage types causing epidemics in cattle. In this study we demonstrate that horizontal transfer of the sopE1 gene by lysogenic conversion with the SopEx increased enteropathogenicity of S. Typhimurium in the bovine ligated ileal loop model. These data support the hypothesis that phage mediated horizontal transfer of the sopE1 gene contributes to the emergence of epidemic cattle-associated S. Typhimurium clones.
Infection and Immunity, 2008
Theriogenology, 2010
The objective was to determine the effectiveness of various antimicrobial agents added to semen e... more The objective was to determine the effectiveness of various antimicrobial agents added to semen extender for inactivation of B. ovis or A. seminis in ovine semen after cryopreservation. In Experiment 1, 20 ejaculates from a crossbred ram infected with B. ovis were cryopreserved in Tris-based extenders with various antimicrobial agents: (I) control without antibiotics, (II) with penicillin and streptomycin (1000 IU/mL and 1 mg/mL, respectively), (III) lincomycin (0.15 mg/mL), (IV) sulphadiazine (0.60 mg/mL), and (V) gentamicin sulphate (0.25 mg/mL). Semen was stored in 0.25 mL straws at a final concentration of 150 × 10(6) spermatozoa/mL. After thawing (37 °C for 30 s), sperm total motility (TM), sperm morphology, integrity of sperm membranes, and bacterial growth were assessed. In Experiment 2, six B. ovis isolates were separately inoculated into aliquots of a fresh ejaculate from a B. ovis-free ram. Mock inoculated semen was processed for cryopreservation using the five extenders d...
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Papers by Renato L Santos