Search

Cystic echinococcosis is a worldwide zoonosis caused by the cestode Echinococcus granulosus. Two types of hydatid cysts occur in intermediate hosts: fertile cysts that generate protoscoleces from the germinal layer of the cyst, and infertile cysts that do not produce protoscoleces and are unable to continue the life cycle of the parasite. The adventitial layer, a host-derived fibrous capsule surrounding the hydatid cyst, is suggested to play an important role in local immune regulation during infection and in fertility of the cysts. Fasciola hepatica, another important parasite of cattle, induces a characteristic Th2-like immune response that could modulate the immune response against E. granulosus. Natural co-infection of both parasites is common in cattle, but no reports describe the local immune response against E. granulosus with F. hepatica infection in the same host. This study analyzed the number and distribution of T and B cells in the adventitial layer of liver and lung cysts and the relationship with cyst fertility and F. hepatica co-infection. T lymphocytes were the predominant cell type in the adventitial layer of infertile hydatid cysts and were more numerous in infertile hydatid cysts. B lymphocyte numbers were not associated with hydatid cyst fertility. Mast cells were infrequent in the adventitial layer. The number of T and B cells was not associated with F. hepatica co-infection. The present study contributes to the understanding of local immune responses in bovine cystic echinococcosis. [ABSTRACT FROM AUTHOR]

Animals infected with Mycobacterium avium subspecies paratuberculosis show a variety of granulomatous lesions that range from focal forms, seen in the subclinical stages, to diffuse lesions associated with clinical signs. The aim of this study was to phenotypically characterize the macrophages present in the different lesion types using immunohistochemical methods. Lesions from a total of 23 animals with bovine paratuberculosis, natural and experimental, were examined by immunohistochemistry. Antibodies against inducible nitric oxide synthase (iNOS), tumor necrosis factor α (TNF-α), CD163, interleukin 10 (IL-10), transforming growth factor β (TGF-β), major histocompatibility complex (MHC) class II, natural resistance-associated macrophage protein 1 (Nramp-1), calprotectin, Ki-67, CD68, lysozyme, and ionized calcium-binding adaptor molecule 1 (Iba-1) molecules were employed. Samples were scored semiquantitatively using a complete histological score (H-score), reflecting the staining intensity and the percentage of immunolabeled macrophages. Differences in the H-score were seen depending on the lesion type. In focal lesions, with none or few acid-fast bacilli (AFB), macrophages were polarized toward M1 phenotype, with high H-scores for iNOS and TNF-α. Diffuse multibacillary lesions showed M2 differentiation, with high expression of CD163, IL-10, and TGF-β as well as Nramp-1 and MHC class II antigens. Macrophages in diffuse paucibacillary forms showed high H-scores for iNOS but low ones for TNF-α. Diffuse lesions, either multibacillary or paucibacillary, showed high calprotectin and low Ki-67 expression, suggesting a progressive character, while focal forms, with low H-scores for these antigens, would be consistent with latency. Lysozyme and CD68 expression were related to the amount of AFB. H-score for Iba-1 antibody was similar among all types. The findings of this study provide insights into the polarization status of macrophages and lesion development in bovine paratuberculosis. [ABSTRACT FROM AUTHOR]

Chicken anaemia virus (CAV) causes chicken infectious anaemia, a severe disease characterized by anaemia and immunosuppression and leading to serious economic losses in the poultry industry worldwide. Although CAV infection has been investigated under experimental conditions, information regarding natural infection is scarce. This report describes an outbreak of CAV infection in 18-day-old broiler chickens and investigates virus tropism in affected birds. Thymic atrophy, pale bone marrow, swelling of the legs and foot ulcers (gangrenous dermatitis) were the most common gross lesions. Severe lymphoid cell depletion in the thymic cortex and presence of intranuclear acidophilic inclusion bodies, depletion of haemopoietic cells in bone marrow and presence of lymphoid infiltrates in several organs were also observed. Immunohistochemical labelling demonstrated the CAV antigens VP1 and VP3 in several organs. The expression of both proteins was similar in the thymic cortex and in the bone marrow, the main target organs of CAV; however, VP3 expression was more abundant in the other organs. Labelling of serial sections showed that CD3 + T lymphocytes might be responsible for the dissemination of the virus from the thymus and bone marrow to other organs and that virus-induced apoptosis, mediated through caspase-3, occurred mainly in the thymus and bone marrow., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Natural killer (NK) cells are a population of innate type I lymphoid cells essential for early anti-viral responses and are known to modulate the course of humoral and cellular-mediated T cell responses. We assessed the role of NK cells in allogeneic CD8 T cell-mediated responses in an immunocompetent mouse model across an MHC class I histocompatibility barrier to determine its impact in therapeutic clinical interventions with polyclonal or monoclonal antibodies (mAbs) targeting lymphoid cells in transplantation. The administration of an NK cell depleting antibody to either CD8 T cell replete or CD8 T cell-depleted naïve C57BL/6 immunocompetent mice accelerated graft rejection. This accelerated rejection response was associated with an in vivo increased cytotoxic activity of CD8 T cells against bm1 allogeneic hematopoietic cells and bm1 skin allografts. These findings show that NK cells were implicated in the control host anti-donor cytotoxic responses, likely by competing for common cell growth factors in both CD8 T cell replete and CD8 T cell-depleted mice, the latter reconstituting in response to lymphopenia. Our data calls for precaution in solid organ transplantation under tolerogenic protocols involving extensive depletion of lymphocytes. These pharmacological biologics with depleting properties over NK cells may accelerate graft rejection and promote aggressive CD8 T cell cytotoxic alloresponses refractory to current immunosuppression.

Conditions causing reproductive failure are a significant concern in the livestock industry, and amongst these, ovine toxoplasmosis is one of the most important. Despite decades of research, there remain gaps in knowledge about this disease, especially regarding the pathogenesis of abortion in sheep. As for other diseases causing ovine abortion, such as chlamydial abortion or border disease, the consequences of infection with Toxoplasma gondii depend largely on the stage of gestation, but the mechanisms involved are not well understood. Immunological modulation occurring during gestation has been proposed as the main mechanism accounting for this clinical variation. However, the extent and effect of such modulation has not yet been identified clearly in sheep and the involvement of other unknown factors has been proposed. Recent experimental studies have defined an unacknowledged clinical presentation of ovine toxoplasmosis, where abortions occur during the acute phase of infection, resulting in as high as 100% fetal loss in susceptible sheep. The pathogenesis of this clinical form differs from that of classically described ovine toxoplasmosis, and its pathological features resemble those of the perinatal syndrome known as cerebral palsy in man. A range of variables, including individual susceptibility, isolate virulence and infective dose, have been proposed as key factors in the development of one or the other of these clinical forms and warrants further investigation in this important disease., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Between 2005 and 2007, the presence of Onchocerca flexuosa (Wedl, 1856) was discovered and investigated in 110 red deer (Cervus elaphus) shot in the Riaño Regional Hunting Reserve, in the province of León (north-western Spain). Nodules containing O. flexuosa were located in the dorsal region and flanks of the deer. These were collected and measured, and some adult parasites were extracted from the nodules and identified by morphology and by obtaining mitochondrial 12S rDNA sequences, which were identical to those of previously published sequences for O. flexuosa. Some nodules were prepared for histology, embedded in paraffin, sectioned and stained with haematoxylin-eosin. Histologically, the worms were found in several compartments separated by an infiltrated fibrous tissue. These compartments were inhabited by several females and males, surrounded by a fibrous capsule. A total of 85.45% (95% confidence interval (CI): 78.86-92.04%) of red deer were parasitized, with a mean intensity of 9.53 ± 12.27 nodules/host, ranging between 1 and 74 nodules/deer. Significant differences in prevalence and intensity of infection were found between young and adult red deer, and also between seasons. However, no significant differences between males and females were observed. Five hundred and ninety-seven nodules were measured (15.81 ± 3.94 mm) and classified by sizes into small ( < 10 mm), medium (10-20 mm) and large (>20 mm). No relation was found between the size of the nodules and the time of infection. The high values found in the studied parameters show that northern Spain is an area of high-intensity infection for deer.

Polyarteritis nodosa (PAN) is a systemic vasculitis of unknown aetiology affecting small- and medium-sized arteries of multiple organ systems without involvement of pulmonary arteries. This report describes four cases of PAN in sheep from different flocks. Three of these animals displayed clinical signs of locomotor disturbance. Gross necropsy findings included bilateral nodular thickening of vessels together with thromboses and aneurysms at several locations. Microscopically, small- to medium-sized arteries of the kidneys, ovary, uterus and skin were consistently involved and other locations were affected less frequently. Arteries within the lung were normal in all animals. Vascular lesions were characterized by focal fibrinoid necrosis, rupture of the internal elastic lamina and transmural infiltration of mononuclear inflammatory cells, extending into the perivascular tissue. In the kidney, many arteries showed narrowing or occlusion of the lumen and marked fibrosis. The distribution of arterial lesions was segmental, showing alternation of affected and microscopically normal areas. Immunohistochemical studies did not identify immune complex deposition. The inflammatory infiltrates were composed of T lymphocytes and macrophages, suggesting that a cell-mediated immune response may be involved in the pathogenesis of this disease., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

A flock of approximately 1,000 sheep were exposed intermittently to food contaminated with T-2 toxin (T-2), a potent type-A trichothecene mycotoxin produced primarily by Fusarium sporotrichioides and Fusarium poae. In the acute stage of the intoxication, affected sheep developed anorexia, decreased water consumption, ruminal atony, soft faeces and apathy. One hundred and ninety of the exposed sheep died. The main gross lesions observed in animals dying during the acute disease were rumenitis and ulcerative abomasitis, depletion of lymphocytes in lymphoid organs, necrosis of the exocrine pancreas, myocarditis and intense oedema of the skin and brain. Sheep developing the chronic stage of disease showed weight loss and reproductive inefficiency and the main pathological features observed in animals dying during this stage were gastrointestinal inflammation, myocardial fibrosis and necrotic and suppurative lesions in the oral cavity. Opportunistic infections (e.g. mycotic mastitis or parasitic pneumonia) were also identified in these animals. Increased serum concentrations of lactate dehydrogenase and creatine kinase were observed, most likely related to heart lesions. T-2 toxins were detected in all samples of the diet of these animals that were analyzed. The changes in the sheep reported here are similar to those described previously in experimental studies. Lesions observed in the present animals suggest an additional cardiotoxic effect of T-2 in sheep., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

This study investigates the nervous form of ovine maedi-visna by histological and immunohistochemical techniques. The aim was to study the lesion types and the local cellular immune response related to each lesion type, and the possible relationship between these parameters. Thirty-four Assaf ewes were studied, 29 of which had shown nervous signs. Microscopical lesion patterns were described according to location, extent and predominance of inflammatory cell type. Immunohistochemical labelling of T cells (CD3(+), CD4(+), CD8(+) and cells expressing the γδ form of the T-cell receptor), B cells and macrophages revealed clear differences between the lesion patterns. Two main lesion types were described. Lymphocytic lesions had areas of mild-moderate injury characterized by a predominance of infiltrating T cells. Histiocytic lesions were more severe and had extensive areas of malacia and dominant infiltration by macrophages and B cells. Each animal had a unique lesion pattern and these differences could be due to individual resistance to the progression of infection. The lymphocytic lesions appear to represent initial or latent phases of slow progression, in which the animal presents some natural resistance to the infection. The histiocytic pattern may reflect a poor immune response or a greater virulence of the viral strain., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Dystrophic epidermolysis bullosa (DEB) was diagnosed in five newborn Assaf lambs from a flock in which around 1-2% of the lambs were lame. Affected animals had marked erythema of the coronary band and subsequent detachment of the hooves. Blisters were present on the lips and in the oral and oesophageal mucosae. Erosions and crusts were noted in the axillary and inguinal areas. Microscopically, there was detachment of the epidermis from the dermis. The roof of these bullous spaces was formed by the intact epidermis with its basement membrane. The bullae were generally filled with pale eosinophilic proteinaceous fluid and erythrocytes. Immunohistochemical analysis revealed absence of collagen VII in the basement membrane zone. The disease in these lambs appears similar to the severe recessive form of human DEB., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Lesions were examined at different levels of the central nervous system (CNS) in 64 sheep with natural maedi-visna (MV) meningoencephalitis. All animals showed lesions in more than one of the CNS locations examined; the lesions in the cranial regions were periventricular, while those in the spinal cord affected the white matter funicles. Lesions were found particularly in the cerebellar peduncles (non-suppurative meningoencephalitis), followed by the corpus callosum, hippocampus and thoracic spinal cord. Vascular, infiltrative and malacic histopathological patterns were recognized. One pattern predominated in each section examined, although mixed forms occurred. Vascular lesions occurred with similar frequency at all CNS levels, but infiltrative and malacic lesions predominated at rostral and caudal levels, respectively. Cells consistent with macrophages and shown immunohistochemically to be associated with MV virus were seen in malacic and infiltrative lesions, at the periphery of damaged areas.

Of 118 sheep with visna, 12 showed myelitis as the only nervous lesion. They were ovine lentivirus (OvLV)-seropositive and provirus DNA was demonstrated by LTR-PCR in all the samples with lesions. Clinically, all showed hindlimb paralysis and some were completely recumbent. Grossly, a swollen and discoloured area was identified in the white matter in 10 sheep. Microscopical changes consisted of a wedge-shaped area of non-suppurative leucomyelitis with mononuclear perivascular cuffing, demyelination and white matter degeneration. Except for two samples, grey matter was affected adjacent to severe white matter lesions. Three different microscopical patterns of lesion were identified, all having in common the presence of perivascular inflammation: the so-called vascular pattern was characterized by perivascular cuffs with minimal lesions in the adjacent neuroparenchyma; the malacic pattern, which was the commonest type, was characterized by severe white matter destruction and small numbers of macrophages; and the infiltrative pattern was characterized by a severe infiltrate of histiocytes in the parenchyma. Maedi-visna virus antigen was detected immunohistochemically only in areas with lesions, and the degree of immunolabelling was unrelated to the severity of the damage. Diagnosticians should bear in mind that a considerable number of visna cases show only spinal cord lesions. Examination of paraffin wax-embedded samples by LTR-PCR and immunohistochemistry would seem useful in confirming a histopathological diagnosis of visna from spinal cord samples.

Paratuberculosis-associated lesions in 116 naturally infected adult cows, with or without clinical signs, were classified histopathologically. Tissue samples obtained focused on gut-associated lymphoid tissue. Lesions were divided into five categories. Focal lesions (n=68 cases), consisted of small granulomas in the ileal and jejunal lymph nodes or the ileocaecal lymphoid tissue. In the multifocal type (n=13 cases), small granulomas or scattered giant cells appeared in some intestinal villi, as well as in the lymph nodes. Diffuse multibacillary lesions (n=15 cases), associated with severe granulomatous enteritis affecting different intestinal locations and lymph nodes, were formed by macrophages containing large numbers of acid-fast bacilli. In diffuse lymphocytic lesions (n=3 cases), lymphocytes were the main inflammatory cells, with some macrophages or giant cells containing few if any mycobacteria. In diffuse intermediate forms (n=17 cases), the infiltrate was formed by abundant lymphocytes and macrophages, and mycobacteria were present to varying degrees related to the number of macrophages. Clinical signs and gross lesions were mainly associated with diffuse forms. Thickening of the intestinal wall, which was the most common macroscopical finding, was related to the degree of submucosal change. Mycobacterium avium subsp. paratuberculosis was identified by culture or PCR in all cows with diffuse lesions, and in 55.5 and 37% of those with multifocal or focal forms, respectively. The importance of sampling the ileal and caudal jejunal lymph nodes to find histological lesions of paratuberculosis in cattle is emphasized.

A meningioma with a significant component of granular cells is described in the left ocular orbit of a 5-year-old male Golden retriever dog that presented with exophthalmos. The neoplastic mass surrounded the optic nerve. Microscopically, the tumour was characterized by nests of large, round to polygonal cells, variable in size, with eccentric nuclei and abundant eosinophilic cytoplasm, containing PAS-positive granules. In focal areas, cells were smaller and occasionally formed whorl-like structures. Immunohistochemical analysis revealed that neoplastic cells reacted positively for vimentin and, with less intensity, for neuron specific enolase and S-100, whereas they were negative for glial fibrillary acidic protein and cytokeratins. Metastatic growths, formed by similar cells, were seen in the lung and heart.

A case of giant cell tumour of bone (GCTb) in the lung and in a subcutaneous mass located in the right flank, with a probable primary origin in the mid-diaphysis of the right tibia, was described in a 8-year-old female cat. Numerous multinucleated giant cells were homogeneously distributed among a population of ovoid or spindle-shaped mononuclear cells. All of them were positive for vimentin suggesting a mesenchymal origin. Spindle-shaped tumour cells resemble fibroblastic cells, showing collagen fibres in their vicinity. Ovoid mononuclear cells are similar to macrophages, with a cytoplasm rich in electron-dense lysosomes. Multinucleated giant cells appear morphologically similar to osteoclasts. These findings are supported for the positive reaction to tartrate-resistant acid phosphatase (TRAP) and lysozyme, encountered only in ovoid and multinucleated giant cells. No immunoreactivity against human oestrogen receptors was observed in the nuclei of any neoplastic cells.

An osteoma located in the frontal bone and nasal cavity is described in a 4-year-old dairy sheep with respiratory difficulty and progressive emaciation. The mass was hard, formed by bone, and caused compression of the ethmoidal labyrinth. Microscopically, the tumour was characterized by trabeculae of woven bone, frequently coexisting with lamellar bone composed of fine fibres, lined by osteoblasts and surrounded by a fibrous stroma. A severe chronic inflammation was seen in the nasal mucosa. Differential diagnosis is discussed, particularly in relation to ossifying fibroma.

The aim of this study was to investigate the cross-resistance between Fasciola hepatica and Schistosoma bovis in lambs assessing parasitologic, gross pathologic, histopathologic and immunohistochemical changes in liver and small intestine. Thirty Castellana breed lambs were divided into five comparable groups and exposed to F. hepatical S. bovis (group F/S), S. bovis/F. hepatica (group S/F), S. bovis (group S) or F. hepatica (group F) and six unexposed lambs were used as non-infected controls (group C). Primary patent infection with F. hepatica induced a lower number of schistosome eggs and a higher number of lymphocytes in intestinal and liver schistosome egg-induced granulomas in group F/S than in the groups S/F and S, liver damage being mainly attributed to F. hepatica. S. bovis infection followed by challenge with F. hepatica particularly increased the severity of the most significant liver alterations (cholangiohepatitis by F. hepatica and mesoendophlebitis by S. bovis) and F. hepatica seemed not to have an influence on established S. bovis infection. In addition, immunohistochemical results suggested that the predominant local immune response in both double-infected groups was different, being mainly a cell-mediated immune response in group F/S and a mucosal response in group S/F.

The purpose of this investigation was to determine the effects of experimental dicrocoeliosis on the hepatic oxidative drug-metabolizing system in hamsters. Studies were carried out 80 and 120 days after infestation with an oral dose of 40 metacercariae of Dicrocoelium dendriticum. The parasitic pathology was ascertained by detection of the fluke eggs in faeces, increased serum alanine aminotransferase and aspartate aminotransferase activities, and postmortem and histological findings. Cytochrome P-450 concentration, aniline hydroxylase activity and ethoxycoumarin O-deethylase activity were significantly decreased in both groups of infected animals. Aminopyrine N-demethylase activity and erythromycin N-demethylase activity were only reduced 120 days after infection. Effects on drug metabolizing enzymes were unrelated to changes in the physical state of the microsomal membrane, as assessed by measurement of fluorescence polarization. The results of this study indicate that the capacity of the liver for handling drugs and xenobiotics may be impaired as a consequence of dicrocoeliosis.