Abstract. Cattle in western Uruguay that were eating Solanum bonariense developed periodic episodes of ataxia, hypermetria, hyperesthesia, head and thoracic limb extension, opisthotonus, nystagmus, and falling to the side or backward. Similar clinical signs were experimentally reproduced in cattle by administration of S. bonariense via rumen cannula at a dose of 1,024 g/kg body mass. No significant gross lesions were observed in field cases or experimentally induced cases. Spontaneous and induced histologic lesions were similar and included vacuolation, degeneration, and loss of Purkinje cells. Axonal spheroids, microcavitations, and other changes of wallerian-type degeneration in cerebellar white matter were also observed. Ultrastructural changes included increased number of electron-dense residual storage bodies in membrane-bound vesicles in affected Purkinje cells, and similar vesicles and mitochondria in axonal spheroids. No histologic lesions were detected in the other examined tissues. The Purkinje-cell swelling and vacuolation with subsequent cerebellar degeneration are suggestive of Purkinje-cell specific toxin that produces abnormal lysosome function and cell specific axonal transport. This is the first report of S. bonariense toxicity.

We examined the ability of pseudorabies virus (PRV) to induce and suppress apoptosis in the trigeminal ganglion during acute infection of its natural host. Eight pigs were intranasally inoculated with a virulent field strain of PRV, and at various early times after inoculation, the trigeminal ganglia were assessed histologically. PRV-infected cells were detected by use of immunohistochemistry and in situ hybridization, and apoptosis was identified by in situ terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling. Light and electron microscopy was also used for morphological studies. Apoptosis was readily detected among infiltrating immune cells that were located surrounding PRV-infected neurons. The majority of PRV-infected neurons did not show morphological or histochemical evidence of apoptosis, even including those neurons that were surrounded by numerous inflammatory cells and exhibited profound pathological changes. However, neuronal virus-induced apoptosis also occurred but at a sporadic low level. These findings suggest that PRV is able to block apoptosis of infected trigeminal ganglionic neurons during acute infection of swine. Furthermore, our results also suggest that apoptosis of infiltrating inflammatory cells may represent an important viral mechanism of immune evasion.

Different tissue culture cell lines infected with a number of alphaherpesviruses produce, in addition to virions, light particles (L particles). L particles are composed of the envelope and tegument components of the virion but totally lack the proteins of the capsid and the virus genome; therefore, they are noninfectious. In this electron microscopy report, we show that L particles are produced during primary replication of the alphaherpesvirus pseudorabies virus (PRV) in the nasal mucosa of experimentally infected swine, its natural host. Although PRV infected different types of cells of the respiratory and olfactory mucosae, PRV L particles were found to be produced exclusively by epithelial cells and fibroblasts. We observed that formation of noninfectious particles occurred by budding of condensed tegument at the inner nuclear membrane and at membranes of cytoplasmic vesicles, resulting in intracisternal and intravesicular L particles, respectively. Both forms of capsidless particles were clearly distinguishable by the presence of prominent surface projections on the envelope and the higher electron density of the tegument, morphological features which were only observed in intravesicular L particles. Moreover, intravesicular but not intracisternal L particles were found to be released by exocytosis and were also identified extracellularly. Comparative analysis between PRV virion and L-particle morphogenesis indicates that both types of virus particles share a common intracellular pathway of assembly and egress but that they show different production patterns during the replication cycle of PRV.The only purpose of a virus is to perpetuate its genome, and this objective is achieved through parasitization of a host cell and subsequent production of infectious progeny. In the case of alphaherpesviruses, virions released from infected cells are the sole product of virus replication with the capacity to infect new cells and thus to maintain the virus in nature. Alphaherpesvirus virions consist of four distinct morphological components, each of them playing an important role in the infectious process: (i) an external lipid bilayer envelope that contains virus-encoded proteins essential for the attachment and fusion of the virus envelope with the plasma membrane of target cells (11,25,36); (ii) a characteristic layer (known as the tegument) consisting of proteins that are transferred into the cytosol immediately after virus entry and that enhance the ability of virions to initiate the process of infection (7,8,32); and (iii) an icosahedral capsid (consisting of 162 capsomers) that contains and transports (iv) a double-stranded linear DNA molecule up to the nuclear envelope, where the capsid interacts with the nuclear pore complexes to release the virus genome into the nucleus (15, 27, 32). After virus gene expression and DNA replication, progeny nucleocapsids assemble in the nucleus and reach the cytoplasm by envelopment followed by deenvelopment at the nuclear membranes. Recent data indicate that the definitive v...

The beneficial effects of anionic salts on calcium metabolism have been shown by supplementing rations with such salts during the last 3 weeks of pre-partum. However, there are few reports on the effects of anionic salts supplementation for periods of 4 weeks or longer on acid-base status, mineral metabolism and bone morphology. This study was conducted to evaluate the effects of the long-term dietary supplementation of anionic salts on the acid-base status, plasma minerals concentrations and bone morphology in sheep. Twenty-seven twin-bearing sheep were assigned to two experimental groups and a control group, depending on dietary cation-anion difference (DCAD) (+272.6, -88.9 and + 164.5 mEq/kg DM, respectively). Sheep assigned to each dietary treatment received their respective rations beginning 6 weeks prepartum and continuing until 12 days post-partum. Diets containing anionic salts induced a mild metabolic hyperchloraemic acidosis from 1 week pre-partum to 2 days post-partum that was completely compensated by non-respiratory mechanisms. These changes on acid-base status were accompanied by an increase of plasma ionized calcium levels. Plasma total calcium, phosphorus and magnesium concentrations were not affected by dietary treatment. Parathyroid hormone concentrations were related to the concentration of ionized calcium of plasma and were higher in sheep fed the cationic diet. Plasma osteocalcin levels were increased in sheep fed the anionic diet and cortical bone remodelling occurred in all the animals during late pregnancy in light and electron microscopy observation, but was particularly evident in the sheep fed the anionic diet. Bone turnover might be stimulated because of the role of the bone in buffering systemic acidosis. The data suggest that anionic salts ameliorated calcium metabolism around parturition by increasing bone resorption and the concentration of ionised calcium in plasma, possibly mediated by a mild hyperchloraemic metabolic acidosis induced by the salts.

Whether bovine haemal nodes are involved in turnover of red blood cells has been a subject of some controversy. In this study, fluorescent and conventional optical microscopy of conventionally or immunohistochemically stained node sections, together with transmission electron microscopy, showed the presence of erythrocyte precursors and megakaryocytes, and evidence of active involvement in the destruction and replacement of old or degenerate red cells and the platelets.

Copolymer I (Cop I) is being tested as a treatment for MS because it protects animals against experimental allergic encephalomyelitis, and because there is immunologic cross-reactivity reported between Cop I and myelin basic protein (MBP). From the peripheral blood mononuclear cells of four normal individuals, we isolated helper-phenotype T-cell lines that reacted in vitro with Cop I or MBP. Cop I-reactive cell lines did not respond to MBP, nor did MBP-reactive T-cell lines respond to Cop I. Antigen-specific immune tolerance was induced in MBP-reactive cell lines by exposure to MBP in vitro, but similar exposure to Cop I did not induce tolerance in the MBP-reactive cell lines. We found no evidence of immunologic cross-reactivity between Cop I and MBP.

Solanum bonariense intoxication is characterized by cerebellar neuronal vacuolation, degeneration, and necrosis. Cerebellar Purkinje cells seem especially susceptible, but more research is needed to determine the pathogenesis of neuronal necrosis and the mechanism of Purkinje cell susceptibility. Calbindin D28k (CbD28k) is highly expressed in Purkinje cells and has been used as a marker for normal and degenerative Purkinje cells. The goal of this study was to describe S bonariense-induced disease by ascertaining Purkinje cell-specific degenerative changes using CbD28k expression and to correlate this with apoptosis in Purkinje cells, as determined using TUNEL (transferase-mediated dUTP-biotin nick end-labeling) and ultrastructural changes. In all cases, an increase in both dose and duration of S bonariense intoxication resulted in a decrease in the number of Purkinje cells. CbD28k immunohistochemistry was an excellent marker for Purkinje cells because immunoreactivity did not change in normal or degenerative tissues. This finding suggests that excessive calcium excitatory stimulation does not induce rapid neuronal degeneration and death. As found in previous studies, TUNEL tests and electron microscopy suggest that Purkinje cell degeneration and death are not occurring via an apoptotic process. These findings suggest that S bonariense poisoning induces progressive Purkinje cell death that is not mediated by excitotoxicity or apoptotic activation.

The bovine haemal nodes are lymphatic organs located in the haemal circulation. Their parenchyma is represented by plasma cells, macrophages and B and T lymphocytes. The T helper type 2 (Th2) CD4 lymphocyte can be found within the T lymphocytes. The activated Th2 CD4 lymphocyte produces interleukin-4 (IL-4), a peptidic hormone involved in the acute-phase immune response. This interleukin can promote either B-lymphocyte differentiation and T-lymphocyte proliferation or it can promote the type of immunoglobulin that can be liberated. Our results have shown, by immunostaining with anti-IL-4, not only the presence and localization of these lymphocytes in bovine haemal nodes but also the participation of polymorphonuclear cells (neutrophils) in the storage of IL-4. These results give value to the humoral and cellular immunological importance of haemal nodes in bovines and they can serve as a contribution to determine the cross-reactivity of bovine IL-4 with the human anti-serum used in this work.