Participation of genes involved in the process of anaerobic respiration of infection in chickens by salmonella typhimurium

Intestinal pathogens are exposed to various stress conditions during their infectious cycle. Anaerobiosis, one of such hostile condition, is offered by the host within gut and intestinal lumen, where survival, multiplication and entry into intestinal epithelial cells are priority for the invasion of the pathogen. The fumarate reductase (frdABCD), dimethyl sulfoxide (DMSO)-trimethylamine N-oxide (TMAO) reductase (dmsABC), and nitrate reductase (narGHIJ) operons in Salmonella Typhimurium (STM) encode enzymes involved in anaerobic respiration to the electron acceptors fumarate, DMSO, TMAO, and nitrate, respectively. They are regulated in response to nitrate and oxygen availability and changes in cell growth rate. Vitamin B12 (cobalamin) is synthesized by Salmonella Typhimurium only under anaerobic growth conditions used as a cofactor in four known reactions. The deletion of cobS and cbiA genes prevent any form of cobalamin production. In the present study we evaluate the infection of birds by mutants of STM, with the anaerobic respiratory system committed by mutations in the genes: narG, napA, cobS, cbiA, frdA, dmsA, and torC. Virulence was assessed by oral inoculation of groups of one-day-old broilers with 0.1 mL of culture contained 10 8 colony forming units (CFU)/mL or diluted at 10 -3 and 10 -2 of strains mutants of Salmonella Typhimurium. Clinical signs and mortality were recorded over a period of 21 days. In general, the symptoms of chickens infected with the mutant strains were similar to those presenting by control birds. Except for STMNalr cbiA, all showed reduced capacity to cause mortality in comparison with the original strain. The mortality of group of chickens infected with STMNal r △narG, STMNal r △frdA, STMNal r △dmsA and STMNal r △cobS△cbiA showed significant decrease in mortality compared to control group (p<0.05).

Serological evidence of Infection by Leishmania (Leishmania) infantum (Synonym: Leishmania (Leishmania) chagasi) in free-ranging wild mammals in a nonendemic region of the state of São Paulo, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Preferential infection sites of Cysticercus bovis in cattle experimentally infected with Taenia saginata eggs

The preferential sites of infection of Cysticercus bovis were evaluated in the skeletal muscle and entrails of 25 cattle that were experimentally infected with Taenia saginata (2 x 10(4) eggs). Two other animals were not inoculated (control). Ninety days after inoculation, all the cattle were euthanized. The carcasses were deboned and dissected into 26 anatomical sections (masseter muscles, brain, tongue, esophagus, heart, diaphragm, lungs, liver, kidneys, spleen, top sirloin butt, bottom sirloin butt, outside round, top (inside) round, transversus abdominus, top sirloin cap, strip loin, full tenderloin, eye of round, knuckle, shoulder clod, foreshank, shank, chuck, back ribs, and tail muscles). The dissected tissues were sliced into 5 mm sections. From the 25 cattle, 9258 C. bovis (cysticerci) were recovered; 75.02% (6946) of these were recovered from skeletal muscles and 24.98% (2312) from the entrails. A high parasitism level was found in the shoulder clod (12.55%), heart (11.02%), liver (9.48%), masseter muscles (8.51%), chuck (8.25%), strip loin and full tenderloin (7.26%), knuckle (6.63%), and back ribs (5.53%), totaling 69.23% (5738) of all of the detected cysticerci. on the other hand, there was a low C. bovis parasitism level in the brain, spleen, tail muscles, kidneys, esophagus, and diaphragm, representing just 3.9% of the total number of cysticerci. Given these results, we conclude that specific skeletal musculature regions, such as the shoulder blade, chuck, strip loin and full tenderloin, knuckle, back ribs and top round, which are not officially examined in many countries, are effective sites to efficiently screen C. bovis infection. To date, these regions have not been considered as preferential sites of C. bovis infection. Based on our work, however, these regions deserve greater attention from health inspectors because they contained a greater number of Cysticercus than the other regions of carcasses that are parasitized by T. saginata larvae. (c) 2010 Elsevier Ltd. All rights reserved.

Effect of Fusarium graminearum and infection index on germination and vigor of maize seeds

Patógenos em sementes de milho (Zea mays) causam sérios problemas, como a perda de sua capacidade germinativa. O objetivo do trabalho foi determinar qual o melhor tempo para infecção das sementes de milho com Fusarium graminearum, para posterior avaliação dos danos causados pelo fungo na germinação e vigor das mesmas. As sementes foram colocadas sobre meio de BDA contendo o patógeno e incubadas por 4, 8, 16 e 32 h. Após os respectivos períodos de incubação, estas foram submetidas ao teste de sanidade (papel de filtro), com duas variações, sem e com assepsia superficial, usando hipoclorito de sódio a 1% de cloro ativo, por 3 min. Determinado o melhor tempo para infecção, outras sementes foram infetadas com o patógeno, para realização dos testes de germinação e vigor (envelhecimento acelerado e teste de frio) com uma mistura de sementes sadias (colocadas sobre o meio BDA) e sementes inoculadas, resultando em 0, 20, 40, 60, 80 e 100% de sementes infetadas com o fungo em estudo. Os resultados obtidos mostraram que o período de incubação de 32 h foi suficiente para se obter sementes infetadas. Com relação à germinação, não houve diferenças significativas entre os diferentes níveis de infecção, provavelmente devido ao alto vigor das sementes de milho testadas. Quanto aos testes de vigor, os níveis de infecção diferiram significativamente da testemunha, apesar de não terem diferido entre si.

Natural infection of gastrointestinal nematodes in long-nosed armadillos Dasypus novemcinctus Linnaeus, 1758 from Pantanal wetlands, Aquidauana sub-region, Mato Grosso do Sul State, with the description of Hadrostrongylus speciosum n. gen. et n. sp (Molineidae : Anoplostrongylinae)

This study evaluated the gastrointestinal helminth fauna of long-nosed armadillos, Dasypus novemcinctus, from the Pantanal wetlands, Aquidauana sub-region, Aquidauana County, Mato Grosso do Sul State, Brazil. Thirteen species of nematodes, comprising seven genera and four families, were recovered from their gastrointestinal tracts. The following descriptors of infection were determined: prevalence, variation of intensity, average intensity and abundance. Hadrostrongylus speciosum n. gen. et n. sp. is first described here. (c) 2006 Published by Elsevier B.V.

Interaction between breeding habitat and elevation affects prevalence but not infection intensity of Batrachochytrium dendrobatidis in Brazilian anuran assemblages

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Clinical, parasitological and immunological aspects of experimental infection with Trypanosoma evansi in dogs

This research investigated the pattern of antibody response by means of enzyme linked immunosorbent assay (Elisa) and indirect fluorescent antibody test (IFAT) through the course of experimental Trypanosoma evansi infection in dogs. Clinical and parasitological features were also studied. The average prepatent period was 11.2 days and parasitaemia showed an undulating course. Biometrical study of parasites revealed a mean total length of 21.68mm. The disease was characterized by intermittent fever closely related to the degree of parasitaemia and main clinical signs consisted of pallor of mucous membrane, edema, progressive emaciation and enlargement of palpable lymph nodes. Diagnostic antibody was detected within 12 to 15 days and 15 to 19 days of infection by IFAT and Elisa, respectively. High and persistent antibody levels were detected by both tests and appeared not to correlate with control of parasitaemia

Susceptibility to Yersinia pseudotuberculosis Infection is Linked to the Pattern of Macrophage Activation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ileal mucosal mast cell, eosinophil, and goblet cell populations during Hymenolepis diminuta infection of the rat

The population dynamics in the enteric connective tissues of eosinophils, mucosal mast cells (MMC), and in the mucosal epithelium of goblet cells were examined morphometrically in fixed ileal tissue of outbred Sprague Dawley rats during the first 32 days of infection with the tapeworm Hymenolepis diminuta. MMC and eosinophils were present in the lamina propria and submucosa; however, only eosinophils were also present in the muscularis externa. Eosinophilic infiltrate was first observed in the lamina propria at 15 days postinfection (dpi) and the numbers of eosinophils remained elevated through 32 dpi. Initial mucosal mastocytosis was detected on 6 dpi and MC numbers continued to rise over the study period without reaching a plateau. Goblet cell hyperplasia occurred only at 32 dpi. In contrast to some intestinal nematode infections where these same 3 cell types are associated with the host's expulsion responses, H. diminuta is not lost by a rapid host response in the outbred Sprague Dawley rat strain used in these experiments. We suggest that either the induction of hyperplasia of these host effector cells in ileum tissue during H. diminuta infection is not capable of triggering parasite rejection mechanisms, or the function of the induced hyperplasia is necessary for some as yet unassociated physiological or tissue architecture change in the host's intestine.

Organ tropism during the acute and chronic phases of Trypanosoma cruzi infection in BALB/c mice

The aim of the present study was to investigate the presence of Trypanosoma cruzi in the heart, liver, lung, and kidneys, using hemoculture and PCR analysis, of mice infected with different parasite strains during the acute and chronic phases of infection. Parasitemia curves revealed strain-specific biological behaviors. For the Y and JLP strains, the acute phase of infection started at days six and ten post-infection, parasitemia peaked at days seven and 15 post-infection, the chronic phase started at days nine and 28 post-infection, and animals started dying at days 19 and 120 post-infection, respectively. When the two strains were compared, the JLP strain exhibited reduced and slower replication rates associated with a delayed peak of parasitism and reduced parasite burdens. However, parasites were detected in all studied organs using PCR analysis. The capacity of both strains to infect different organs likely influences disease pathogenesis.

Experimental infection of Leishmania chagasi in immunosuppressed balb/c mice: cellular immune response and parasite burden

The immune response to leishmaniasis can result in a polarization of a subpopulation of T lymphocytes, which leads to a different cell phenotype and results in immune protection or exacerbation of the disease. Leishmanias persist in the body both in asymptomatic infections and after treatment, representing risks in terms of immunosuppression. The objective of this study was to evaluate the effects of infection and immunosuppression by dexamethasone associated with pentoxifylline on animal weight, spleen weight, the parasitic load in the spleen and liver, as well as the production of IFN-gamma and IL-10 in spleen cell culture of Balb/c mice infected with Leishmania chagasi. The infection did not alter animal weight gain, but spleen weight and size increased. The immunosuppression, induced by dexamethasone associated with pentoxifylline, affected animal weight gain and weight and size of the spleen (in infected and not infected animals). The immunosuppression did not significantly alter the course of the parasite burden in the spleen and liver. Dexamethasone and pentoxifylline affected the studied cytokine production, but not influenced on Th1/Th2 response in infected animals.

Analysis of the expression of toll-like receptors 2 and 4 and cytokine production during experimental Leishmania chagasi infection

Toll-like receptors (TLRs) recognise pathogen-derived molecules and influence immunity to control parasite infections. This study aimed to evaluate the mRNA expression of TLRs 2 and 4, the expression and production of the cytokines interleukin (IL)-12, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, IL-17, IL-10 and transforming growth factor (TGF)-β and the production of nitric oxide (NO) in the spleen of mice infected with Leishmania chagasi. It also aimed to evaluate any correlations between mRNA expression TLR2 and 4 and cytokines and NO production. Infection resulted in increased TLR2-4, IL-17, TNF-α and TGF-β mRNA expression during early infection, with decreased expression during late infection correlating with parasite load. IFN-γ and IL-12 mRNA expression decreased at the peak of parasitism. IL-10 mRNA expression increased throughout the entire time period analysed. Although TGF-β, TNF-α and IL-17 were highly produced during the initial phase of infection, IFN-γ and IL-12 exhibited high production during the final phase of infection. IL-10 and NO showed increased production throughout the evaluated time period. In the acute phase of infection, there was a positive correlation between TLR2-4, TNF-α, IL-17, NO, IL-10 and TGF-β expression and parasite load. During the chronic phase of infection, there was a positive correlation between TLR2-4, TNF-α, IL-17 and TGF-β expression and parasite load. Our data suggest that infection by L. chagasi resulted in modulation of TLRs 2 and 4 and cytokines.

Cell-mediated immune response to Leishmania chagasi experimental infection of BALB/c immunosuppressed mice

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cryptosporidium spp. infection in mares and foals of the northwest region of São Paulo State, Brazil

O presente estudo teve como objetivo analisar a ocorrência da infecção por Cryptosporidium spp. em éguas e seus respectivos potros. Este estudo foi realizado em 11 fazendas localizadas nos municípios de Araçatuba, Birigui, Guararapes e Santo Antônio do Aracangua, na região Noroeste do Estado de São Paulo, de novembro de 2010 a março de 2011. Um total de 98 éguas e 98 potros de diversas raças foram analisados, sendo que, entre os filhotes, 59 eram machos e 39 fêmeas, cujas idades variavam de três até 330 dias. Fezes foram colhidas diretamente da ampola retal, purificadas e processadas pela técnica de Kinyoun modificada. A ocorrência de Cryptosporidium spp. observada foi de 21,4% (21/98) para potros e 18,4% (18/98) para éguas. A ocorrência de Cryptosporidium spp. teve uma associação significativa com a raça e a idade dos animais. A partir dos resultados obtidos, conclui-se neste estudo que potros com idade superior a dois meses e animais da raça Mangalarga foram menos susceptíveis à ocorrência de Cryptosporidium spp.