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Infection by the acanthocephalan Neoechinorhynchus buttnerae is considered the most important obstacle in farmed tambaqui or cachama (Colossoma macropomum), the second most cultivated fish species in Brazil. This study describes the occurrence of N. buttnerae in farmed this fish based on parasitological and histopathological analysis in highly infected fish. A total of 102 fish were collected from fish farms located in Brazilian states in the northern region. All of the examined fish were heavily infected by N. buttnerae and showed no signs of anorexia, but heterogeneous growth and cachexia were frequently found. No cases of mortality were observed in fish farms. Macroscopically, the intestines showed hyperaemia, hardening, thickening of the intestinal wall, yellowish mucosal secretion and a bluetongue aspect. Histological sections showed different degrees of penetration of the acanthocephalan proboscis in the intestinal tissue, surpassing the mucosa, submucosa and muscular layer, provoking dilacerations due to their spines as well as an intense inflammatory reaction composed of macrophages, Langerhans cells and lymphocytes, and granuloma formation located mainly in the submucosa layer. Submucosal oedema, an increased number of goblet cells, metaplasia areas and a reduction of the intestinal villi were also observed. The results present an important register of N. buttnerae infection in C. macropomum and contribute to the comprehension of pathogeny caused by these worms. Statement of relevance: Characid fish farming has led to significantly increased fish production in Brazil. However, the most important obstacle is the acanthocephalan infection caused by Neoechinorhynchus buttnerae in the intestinal tract. The infection does not provoke death but cachexia and growth reduction are frequently observed as well as intense pathological conditions in histological sections.

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-The objective of this work was to evaluate the effect of food supplementation with vitamin C on macrophage and multinucleated giant cell (MGC) activities of pacus at two stocking densities. The experiment was carried out in a 2x2x3 split-plot factorial arrangement with: 0 and 500 mg kg -1 vitamin C; 5 and 20 kg m -3 stocking densities; and evaluation times at 3, 6, and 12 days after the subcutaneous implantation of glass coverslips (DPI). The number of macrophages and MGC, as well as cortisol and glucose plasma levels were determined. The number of macrophages and MGC with two to five nuclei was significantly greater in fish supplemented with vitamin C at 5 kg m -3 stocking density at 3 DPI in comparison to nonsupplemented ones. The macrophage and MGC counts were lower in fish with high-plasma cortisol concentration. Supplementation with 500 mg vitamin C benefits macrophage activity on foreign-body inflammation, and high-cortisol concentration has suppressive effects on this response.Index terms: Piaractus mesopotamicus, ascorbic acid, glucocorticoid, inflammation, Langhans cells, multinucleated giant cells. Vitamina C e cortisol endógeno em resposta inflamatória tipo corpo estranho em pacusResumo -O objetivo deste trabalho foi avaliar o efeito da suplementação com vitamina C no aumento da atividade de macrófagos e células gigantes multinucleadas (CGM), em pacus mantidos em duas densidades de estocagem. O experimento foi realizado em parcelas subdivididas, em arranjo fatorial 2x2x3 com: 0 e 500 mg kg -1 de vitamina C; densidade de estocagem de 5 e 20 kg m -3 ; e tempos de avaliação de 3, 6 e 12 dias após o implante subcutâneo (DPI) de lamínulas de vidro. Foram determinados o número de macrófagos e de CGM, bem como os níveis de cortisol e glicose no plasma. O número de macrófagos e de CGM com 2 a 5 núcleos foi significativamente maior nos peixes suplementados com vitamina C, à densidade 5 kg m -3 , aos 3 DPI, em relação aos não suplementados. Constatou-se menor quantidade de macrófagos e CGM em peixes com baixa concentração plasmática de cortisol. A suplementação com 500 mg de vitamina C por quilograma de ração beneficia a atividade de macrófagos em inflamações do tipo corpo estranho, e a elevada concentração de cortisol circulante tem efeito supressor nesta resposta.Termos para indexação: Piaractus mesopotamicus, ácido ascórbico, glicocorticoide, inflamação, células de Langhans, células gigantes multinucleadas.

Acute-phase protein (APPs) serum levels have been studied in many human diseases, and their components contribute to host defense during the evolution of infectious diseases by acting as part of the innate immune system. Based on the importance of establishing new experimental models, the present investigation evaluated the modulation of APPs following inflammatory stimulus by the inoculation of Aeromonas hydrophila in tilapias. Fish were sampled 6 and 24 hours post-infection. Tilapias presented increase of positive APPs such as ceruloplasmin, haptoglobin, alpha-2-macroglobulin and complement C3, as well as decrease of negative APPs such as albumin and transferrin. The protein response of tilapias during the course of bacterial infection showed correlation with the kinetics of cellular accumulation in the inflamed focus with significant increase of granulocytes, thrombocytes, lymphocytes and macrophages. However, granulocytes were the predominant cells, associated with increment in the reactive oxygen species (ROS) production. Showing responses similar to those observed in humans, the modulation of APPs and the kinetics of cellular accumulation in the exudate demonstrate the feasibility of this alternative experimental model for advances and studies to understand changes in pathophysiological mechanisms of acute inflammatory reaction due to bacterial infection.

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The present study aimed to describe and characterize the cellular components during the evolution of chronic granulomatous inflammation in the teleost fish pacus (P. mesopotamicus) induced by Bacillus Calmette-Guerin (BCG), using S-100, iNOS and cytokeratin antibodies. 50 fish (120±5.0 g) were anesthetized and 45 inoculated with 20 μL (40 mg/mL) (2.0 x 106 CFU/mg) and five inoculated with saline (0,65%) into muscle tissue in the laterodorsal region. To evaluate the inflammatory process, nine fish inoculated with BCG and one control were sampled in five periods: 3rd, 7th, 14th, 21st and 33rd days post-inoculation (DPI). Immunohistochemical examination showed that the marking with anti-S-100 protein and anti-iNOS antibodies was weak, with a diffuse pattern, between the third and seventh DPI. From the 14th to the 33rd day, the marking became stronger and marked the cytoplasm of the macrophages. Positivity for cytokeratin was initially observed in the 14th DPI, and the stronger immunostaining in the 33rd day, period in which the epithelioid cells were more evident and the granuloma was fully formed. Also after the 14th day, a certain degree of cellular organization was observed, due to the arrangement of the macrophages around the inoculated material, with little evidence of edema. The arrangement of the macrophages around the inoculum, the fibroblasts, the lymphocytes and, in most cases, the presence of melanomacrophages formed the granuloma and kept the inoculum isolated in the 33rd DPI. The present study suggested that the granulomatous experimental model using teleost fish P. mesopotamicus presented a similar response to those observed in mammals, confirming its importance for studies of chronic inflammatory reaction.

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