Pathogenesis of Equid Alphaherpesvirus 1 Infection in the Central Nervous System of Mice.

Equid alphaherpesvirus 1 (EHV-1) causes myeloencephalopathy in horses and occasionally in non-equid species. Although mouse models have been developed to understand EHV-1 pathogenesis, few EHV-1 strains have been identified as highly neurovirulent to mice. The aim of this study was to evaluate the pathogenesis of 2 neurovirulent EHV-1 strains in mice, and to characterize the inflammatory cells and expression of chemokines and the apoptosis marker caspase-3 in the brain of infected mice. C57BL/6J mice were inoculated intranasally with EHV-1 strains A4/72 or A9/92 and evaluated on 1, 2, and 3 days post inoculation (DPI). EHV-1-infected mice showed severe neurological signs at 3 DPI. Ultrastructural analysis revealed numerous viral nucleocapsids and fewer enveloped virions within degenerated and necrotic neurons and in the surrounding neuropil. Histologically, at 3 DPI, there was severe diffuse neuronal degeneration and liquefactive necrosis, prominent microgliosis, and perivascular cuffing composed of CD3+ cells (T cells) and Iba-1+ cells (macrophages), mainly in the olfactory bulb and ventral portions of the brain. In these areas, moderate numbers of neuroglial cells expressed CCL5 and CCL2 chemokines. Numerous neurons, including those in less affected areas, were immunolabeled for cleaved caspase-3. In conclusion, neurovirulent EHV-1 strains induced a fulminant necrotizing lymphohistiocytic meningoencephalitis in mice, with microgliosis and expression of chemokines and caspase-3. This model will be useful for understanding the mechanisms underlying the extensive neuropathology induced by these viral infections.

Equine herpesvirus 1 elicits a strong pro-inflammatory response in the brain of mice.

Equine herpesvirus type 1 (EHV-1) is an emerging pathogen that causes encephalomyelitis in horses and non-equid species. Several aspects of the immune response in the central nervous system (CNS), mainly regarding the role of inflammatory mediators during EHV-1 encephalitis, remain unknown. Moreover, understanding the mechanisms underlying extensive neuropathology induced by viruses would be helpful to establish therapeutic strategies. Therefore, we aimed to evaluate some aspects of the innate immune response during highly neurovirulent EHV-1 infection. C57BL/6 mice infected intranasally with A4/72 and A9/92 EHV-1 strains developed a fulminant neurological disease at 3 days post-inoculation with high viral titres in the brain. These mice developed severe encephalitis with infiltration of monocytes and CD8+ T cells to the brain. The inflammatory infiltrate followed the detection of the chemokines CCL2, CCL3, CCL4, CCL5, CXCL2, CXCL9 and CXCL-10 in the brain. Notably, the levels of CCL3, CCL4, CCL5 and CXCL9 were higher in A4/72-infected mice, which presented higher numbers of inflammatory cells within the CNS. Pro-inflammatory cytokines, such as interleukins (ILs) IL-1α, IL-1ß, IL-6, IL-12ß, and tumour necrosis factor (TNF), were also detected in the CNS, and Toll-like receptor (TLR) TLR2, TLR3 and TLR9 genes were also upregulated within the brain of EHV-1-infected mice. However, no expression of interferon-γ (IFN-γ) and IL-12α, which are important for controlling the replication of other herpesviruses, was detected in EHV-1-infected mice. The results show that the activated innate immune mechanisms could not prevent EHV-1 replication within the CNS, but most likely contributed to the extensive neuropathology. The mouse model of viral encephalitis proposed here will also be useful to study the mechanisms underlying extensive neuropathology.

Heterogenous deposition of ß-amyloid in the brain of aged dogs.

Dogs have been used as animal models for human diseases in which there is beta-amyloid (Aß) deposition in the central nervous system (CNS), such as Alzheimer's and cerebral amyloid angiopathy (CAA). However, many aspects of Aß deposition in the CNS of dogs still remain unknown. This study aimed to evaluate the deposition of Aß in different areas of the CNS of aged dogs from different breeds. Aß was detected in the brains of aged dogs, forming either senile plaques in the neuropil of cortical gray matter or within the walls of parenchymal or leptomeningeal blood vessels. There was a positive correlation between aging and senile plaques or CAA. In dogs older than 8 years, there was no correlation between the area of Aß plaques and age, with frontal, temporal, and occipital cortices being affected with approximately equal frequency. There was a positive correlation between Aß deposition in vessel walls and age. Importantly, CAA was associated with the occurrence of microperivascular hemorrhages in the brains of aged dogs. In conclusion, this study demonstrated that Aß deposition as plaques or within vessel walls are extremely heterogenous in dogs from different breeds and sizes. Although many features of this disease in dogs are similar to those observed in humans, the choice of dog breed and size as a model for human disease will substantially affect the pattern of Aß deposition.

Placental lesions associated with abortion and stillbirth in goats naturally infected by Neospora caninum / Lesões placentárias associadas a abortos e natimortos em cabras naturalmente infectadas pelo Neospora caninum

Neospora caninum has been described as a parasite that sporadically causes reproductive problems in goats. Several aspects of the pathogenesis of neosporosis in naturally infected goats remain to be established. The aims of the present study were to characterize the placental lesions in goats naturally infected by N. caninum and to evaluate several diagnostic techniques for effective detection of this protozoan in the goat placenta. Some placentas in this study originated from abortion and stillbirth in which there were severe lesions. The lesions were characterized mainly by necrosis involving the mesenchyme of the chorionic villi and trophoblast cells often alongside mononuclear inflammation and in some cases with neutrophilic infiltration. N. caninum DNA was detected in these placentas, but parasite structures were not visualized through immunohistochemistry (IHC). However, five of 11 placentas from N. caninum-infected goats that gave birth to healthy kids had histological lesions characterized by mononuclear inflammation. Of these 11 placentas, N. caninum DNA was detected in seven, and N. caninum tachyzoites were detected in only one of these seven placentas using IHC. The present study demonstrates that severe lesions in the placenta are associated with abortion and stillbirth in caprine neosporosis and the placental alterations are likely involved in abortion pathogenesis. Moreover, the results highlight the importance of using more than one diagnostic technique for the detection of the protozoan in placentas because N. caninum cannot be reliably detected by histological and immunohistochemical tests.(AU)

Neospora caninum é descrito como um parasito que causa problemas reprodutivos esporádicos em cabras. Muitos aspectos da patogênese da neosporose em cabras naturalmente infectadas ainda precisam ser estabelecidos. Os objetivos deste trabalho foram caracterizar as lesões placentárias em cabras naturalmente infectadas por N. caninum e avaliar as técnicas diagnósticas para a detecção efetiva do protozoário na placenta. Algumas placentas deste estudo são originárias de abortos e natimortos, nas quais havia lesões graves. As lesões foram classificadas principalmente por necrose envolvendo o mesênquima das vilosidades coriônicas e células trofoblásticas, geralmente associadas a infiltrado inflamatório mononuclear e em alguns casos infiltrado neutrofílico. O DNA do N. caninum foi detectado nestas placentas, porém estruturas parasitárias não foram visualizadas na imuno-histoquímica (IHQ). Entretanto, cinco das onze placentas de cabras infectadas, que deram à luz a conceptos saudáveis, apresentaram lesões histológicas caracterizadas por infiltrado inflamatório mononuclear. Destas 11 placentas, foi detectado DNA de N. caninum em sete e taquizoítos foram encontrados em apenas uma por meio de imuno-histoquímica. O presente estudo demonstra que abortos e natimortos na espécie caprina, causados pelo N. caninum estão associados a lesões acentuadas nas placentas, sendo que as mesmas estão envolvidas na patogênese do aborto. Os resultados também ressaltam a importância do uso de mais de uma técnica diagnóstica para a detecção do protozoário em placentas, pois o N. caninum não pode ser confiavelmente detectado somente pelos exames de histopatologia e imuno-histoquímica.(AU)

Glial response in the central nervous system of cats with feline infectious peritonitis.

OBJECTIVES: The aim of the study was to evaluate central nervous system (CNS) lesions in non-effusive and effusive cases of feline infectious peritonitis (FIP) regarding aspects related to astrocytic and microglial reactions. METHODS: Five necropsied cats that were naturally infected with FIP virus, confirmed by reverse transcriptase polymerase chain reaction and immunohistochemistry, with different intensities of CNS lesions, were studied. Brain and cerebellum were evaluated by light microscopy and immunohistochemistry for glial fibrillary acidic protein (GFAP) and vimentin to assess astrocytic morphology, and lectin histochemistry for Ricinus communis agglutinin-I (RCA-I) to detect microglia was performed to evaluate the glial response in the CNS of cats with FIP. RESULTS: An important astrocytic response in many areas of the CNS of all cats, including the periventricular areas of lateral ventricles and fourth ventricle, the molecular layer of the cerebellum and cerebral cortex, was visualized. This astrocytic reactivity was associated with areas of granulomatous or pyogranulomatous vasculitis/perivasculitis in most cases, and it was characterized by multifocal to coalescing astrocytosis and astrogliosis with an increase in the expression of intermediate filaments, such as GFAP. However, astrocytes exhibited strong vimentin expression in neuroparenchyma with severe inflammatory and necrotic changes, but GFAP expression was mild or absent in these cases. A microglial response was present only in severe lesions, and RCA-I expression was detected primarily in gitter cells and resting microglia. CONCLUSIONS AND RELEVANCE: The present study indicates a strong astrocytic response, including the presence of many less differentiated vimentin-positive astrocytes and gitter cells positive for RCA-1 in severe lesions in the CNS of cats with FIP.

Aspectos histopatológicos das lesões renais em gatos experimentalmente infectados pelo vírus da imunodeficiência felina / Histopathological aspects of renal lesions in cats experimentally infected with feline immunodeficiency virus

A infecção pelo vírus da imunodeficiência felina (FIV) em gatos domésticos é caracterizada por distúrbios imunológicos, que geralmente se manifestam tardiamente na doença. Semelhante à infecção pelo vírus da imunodeficiência humana (HIV) em humanos, a infecção pelo FIV geralmente está associada a infecções oportunistas e ao desenvolvimento progressivo de nefropatia. Portanto, o objetivo do presente estudo foi avaliar as alterações histopatológicas em rins de 10 gatos experimentalmente infectados pelo FIV submetidos a eutanásia 60 meses após a inoculação viral. Nos rins de 100% dos gatos infectados pelo FIV foram visualizadas lesões glomerulares e tubulointersticiais. As lesões glomerulares eram caracterizadas principalmente por espessamento global ou segmentar da membrana basal glomerular (glomerulonefrite membranosa). Glomeruloesclerose e, em dois casos, proliferação de células epiteliais intraglomerulares (crescente glomerular), também foram observados. Nefrite intersticial linfoplasmocítica foi a alteração tubulointersticial mais frequente, visualizada em diferentes intensidades nos rins de 100% dos gatos. Os resultados do presente estudo demonstram que o tempo prolongado entre a infecção e a avaliação histopatológica pode ter sido decisivo para o surgimento das lesões renais em todos os gatos infectados pelo FIV e para o agravamento dessas lesões em alguns gatos...

The feline immunodeficiency virus (FIV) infection in domestic cats is characterized by immunological disorders that commonly manifest in a later stage of the disease. Similarly to the human immunodeficiency virus (HIV) infection in humans, FIV infection is commonly associated with opportunistic infections and progressive development of nephropathies. Therefore, the aim of the present study was to perform histological evaluation of the kidneys of 10 cats experimentally infected with FIV and euthanized at 60 months after viral inoculation. In the kidneys of 100% of the cats infected with FIV, glomerular and tubulointerstitial lesions were seen. The glomerular lesions were mainly characterized by global or segmental thickening of the glomerular basement membrane (membranous glomerulonephritis). Glomerulosclerosis, and in two cases, proliferation of intraglomerular epithelial cells (glomerular crescent) were also observed. The intersticial lymphoplasmacytic nephritis was the tubulointerstitial alteration most frequent and was observed in different intensity levels in 100% of the cats. The results of the present study demonstrate that the prolonged time between infection and histopathological evaluation may have been decisive for the arising of renal lesions in all cats infected with FIV and for the increase of these lesions in some cats...

Histopathology and immunohistochemistry of tissues outside central nervous system in bovine rabies.

We performed a histopathological and immunohistochemical study of tissues outside the central nervous system in 48 cases of bovine rabies confirmed by direct immunofluorescence and/or immunohistochemistry (IHC) of the central nervous system. In the bovines of this study, mononuclear inflammation in all ganglia (trigeminal, spinal, stellate, and celiac) and adrenal medulla was observed. This injury also occurred in 85 % of neuro-pituitaries in 55 % of pars intermediate and 15 % of the pars distalis of pituitary evaluated. IHC was positive in 92.31 % of lumbar spinal ganglia, 90.9 % of trigeminal ganglia, stellate ganglia of 41.67 and 16.67 % of the celiac ganglia. One of the evaluated adrenal (1/17) showed strong immunohistochemical labeling in the cytoplasm of pheochromocytes. The pituitary IHC was positive in one case in the neurohypophysis (1/20) and in one case in the pars intermedia of the adenohypophysis (1/20). Data from this study indicate that in suspected cases of rabies, besides the complex pituitary rete mirabile and trigeminal ganglion, the evaluation of other ganglia, particularly the lumbar spinal, and adrenal may also contribute to the diagnosis and understanding of the clinical presentation and pathogenesis of the disease in bovines.

Antibody kinetics in goats and conceptuses naturally infected with Neospora caninum.

Neospora caninum is a protozoan which can cause abortions in caprines. However, information regarding the humoral immune response and the occurrence of reproductive disorders is scarce. This is the first study in which the kinetics of antibodies is studied in pregnant goats naturally infected by N. caninum, as well as their respective conceptuses. The subclasses of IgG (IgG1 and IgG2) were also evaluated in pregnant goats. Reproductive problems related to neosporosis (abortion and stillbirth) occurred in 15.38% of the goats. There was a statistically significant association between the increased titres of maternal IgG in the second half of the gestational period with the occurrence of endogenous transplacental transmission. The rate of congenital transmission was 77%. During the gestational period of the seropositive goats, there was mainly a predominance of the subclass IgG2, although mixed patterns of IgG2-IgG1 and the IgG1 pattern were also observed. These results indicate that N. caninum is responsible for the occurrence of important alterations in the humoral immune response of naturally infected goats, and is also a potential causative agent for reproductive disorders in goats. The high proportion of infected conceptuses reinforces the suggestion that congenital infection is one of the main routes of parasite transmission in goats.

Prevalência e aspectos anatomopatológicos das neoplasias primárias do coração, de tecidos da base do coração e metastáticas, em cães do Sul de Minas Gerais (1994-2009) / Prevalence and anatomopathological findings of primary cardiac neoplasms of the heart base tissues and metastases in dogs from southern Minas Gerais, Brazil (1994-2009)

Este estudo teve como objetivo determinar a prevalência e achados anatomopatológicos de tumores primários e metastáticos do coração ou de tecidos da base do coração, diagnosticados em caninos do Sul de Minas Gerais. O diagnóstico foi realizado mediante análise histopatológica e imuno-histoquímica das neoplasias. Durante os anos de 1994-2009, foram realizadas 2397 necropsias em caninos. Neoplasias no coração foram detectadas em 31 cães (1,29%), onde, sete (22,58%) eram primárias e 24 (77,42%) metastáticas. As neoplasias diagnosticadas como primárias do coração foram o hemangiossarcoma (1/7) e o mixoma (1/7); e como primárias da base do coração o quimiodectoma (3/7) e o carcinoma de tireoide ectópica (2/7). A frequência foi maior em cães machos (5/7), da raça Boxer (3/7) e com idade média de 9,7±1,88 anos. Nas neoplasias metastáticas, a frequência foi maior em fêmeas (15/24), em cães da raça Rottweiler (7/24) e a idade média foi de 7,5±3,23 anos, sendo o linfoma de células T a neoplasia metastática de maior ocorrência (7/27).

The purpose of this study was to determine the prevalence and anatomopathological findings of primary and metastatic heart tumors and from heart base tumors diagnosed in dogs from southern Minas Gerais, Brazil. The diagnosis was based on histological characteristics and immunophenotyping of the tumors cells. From 1994 to 2009, 2397 necropsies of dogs were performed. Cardiac neoplasms were diagnosed in 31 dogs (1.29%), where seven (22.58%) were primary and 24 (77.42%) were metastatic. Neoplasms of the heart diagnosed as primary were hemangiosarcoma (1/7) and myxoma (1/7), and, primary of heart base, the chemodectoma (3/7) and ectopic thyroid carcinoma (2/7). Frequency was higher in male dogs (5/7), of Boxer breed (3/7) with mean age of 9.7±1.88 years. In metastatic neoplasms, the frequency was higher in female dogs (15/24), of Rottweiler breed (7/24) with the mean age of 7.5±3.23 years. The T cell lymphoma (7/27) was the most frequent neoplasm, diagnosed as metastatic.

Domestic microwave processing for rapid immunohistochemical diagnosis of bovine rabies.

The present study describes the use of a microwave processing protocol for the rapid histopathological and immunohistochemical diagnosis of bovine rabies. Immunohistochemistry has been used for rabies diagnosis in formalin-fixed tissue with satisfactory results, although the time to diagnosis is considerably longer than that with direct immunofluorescence. The protocol provided a provisory histopathological rabies diagnosis in approximately three and half hours and the immunohistochemical diagnosis was available after six hours. The protocol achieved 100% correlation with direct immunofluorescence and is a promising method, particularly in situations in which only material in formalin is available for diagnosis or when the refrigeration or transportation of biological material is difficult.

Surto de compactação primária de abomaso em bovinos leiteiros associado ao consumo de silagem de girassol / Outbreak of primary abomasal impaction in dairy cattle associated with consumption of sunflower silage

Um surto de compactação primária de abomaso associada ao consumo de silagem de girassol ocorreu num rebanho bovino leiteiro do estado de Minas Gerais, do qual seis de 21 vacas secas em fase final de gestação e que recebiam silagem de girassol morreram. Os bovinos que adoeceram apresentaram distensão abdominal, fezes ressecadas e escassas e, nos bovinos que morreram, eram pastosas, escuras e fétidas; nesses havia também desidratação acentuada e palidez de mucosas. Três bovinos foram necropsiados e os achados patológicos eram constituídos principalmente por distensão acentuada do abomaso associada a grande quantidade de conteúdo alimentar ressecado coberto por coágulos de sangue. No abomaso havia úlceras, com perfuração da parede em um dos bovinos. A alimentação de bovinos de maior exigência nutricional com silagem de girassol de características indesejáveis como única fonte de volumoso foi o principal fator para a compactação de abomaso nos casos apresentados.

An outbreak of primary abomasal impaction associated with consumption of sunflower silage occurred in a dairy cattle herd from the state of Minas Gerais. Six of 21 dry cows in late pregnancy fed with sunflower silage died. Cattle that became ill presented abdominal distension and scant and dried feces. In the animals that died, severe dehydration, pale mucous membranes, dark, sticky and stinking feces were seen. Three cows were necropsied and the main pathological findings consisted of severe abomasal distension associated with a large quantity of dried alimentary content covered by bloody clots. Ulcers were found in abomasum, with perforation in one cow. Feeding cattle with high nutritional needs, with sunflower silage of undesirable characteristics as unique source of roughage was the main cause for the abomasal impaction.

Fatores associados a soroprevalência de neospora caninum e toxoplasma gondii em rebanhos caprinos na região sul de Minas Gerais / Factors associated to seroprevalence of neospora caninum and toxoplasma gondii in caprine herds in southern Minas Gerais state, Brazil

Este estudo estabelece a soroprevalência de Neospora caninum e Toxoplasma gondii em rebanhos caprinos no Sul de Minas Gerais e verifica a sua associação com o desempenho reprodutivo dos rebanhos analisados, uma vez que não há dados sobre neosporose em caprinos neste Estado. Amostras de soro de 401 caprinos provenientes de 11 propriedades foram submetidas à reação de imunofluorescência indireta anti-N. caninum e T. gondii. A prevalência média de animais positivos foi de 10,7% e 21,4%, respectivamente. Houve diferença significativa entre as faixas etárias. Neste quesito os maiores índices de positividade, para ambos os parasitas, foram observados nos caprinos acima de três anos de idade. Estes apresentaram uma probabilidade 2,6 e 4,8 maior, em relação aos animais de até um ano de idade, para N. caninum e T. gondii, respectivamente. No teste T não houve associação positiva entre as médias de prevalência de N. caninum (p=0,553) e T. gondii (p=0,098) com a ocorrência de problema reprodutivo nos rebanhos. Porém, propriedades com histórico de problemas reprodutivos apresentaram uma média de reagentes para N. caninum de 18,64%, se comparadas a 13,97% de criatórios que não relataram essas alterações. Quando os problemas reprodutivos foram separados em categorias a relação entre a ocorrência de aborto e a soroprevalência de N. caninum e de T. gondii foi significativa (p<0,05) por meio dos testes Exato de Fisher e Qui-quadrado. Não houve diferença (p>0,05) entre as médias de prevalência de T. gondii e o acesso de gatos ao rebanho no teste T. Entretanto, a média de prevalência nas propriedades em que os gatos tinham acesso foi de 31,01%, se comparada a 17,34% em criatórios onde não existiam gatos. Foi constatado o acesso de cães em 100% das propriedades. Os resultados obtidos neste estudo demonstram que N. caninum e T. gondii infectam caprinos no Sul de Minas Gerais e que estes parasitas podem estar associados à ocorrência de abortos nessa espécie animal.

This study determines the seroprevalences of Neospora caninum and Toxoplasma gondii in caprine herds in southern Minas Gerais state and investigates their association with the reproductive performance of the herds analyzed since no data concerning neosporosis in goats in this state are available. Serum samples from 401 goats from 11 farms were subjected to indirect immunofluorescence reaction for the detection of N. caninum and T. gondii. The mean prevalence rates of animals that tested positive were 10.7% and 21.4%, respectively. Significant differences between different age groups were observed. The highest frequencies of positive cases for both parasites were observed in goats over three years of age; in this group, the probability of seropositivity for N. caninum and T. gondii was 2.6 and 4.8 times higher, respectively, when compared to animals up to one year of age. No positive correlation was found between the mean prevalence rate of N. caninum (p-0,553) and T. gondii (p=0.098) and the occurrence of reproductive problems in the herds using T-test. However, farms with a history of reproductive problems exhibited an average of 18.64% animals reactive to N. caninum, compared to 13.97% from farms where those problems were not reported. When reproductive problems were separated in category, the relationship between occurrence of abortion and seroprevalence of N. caninum and T. gondii was significant (p<0.05) using Fisher’s exact test and chi-square test. No difference was seen (p>0.05) between the mean prevalence rate of T. gondii of herds to which cats had access as compared to herds that had no contact with cats using a Ttest. However, the mean prevalence rate in farms where cats had access to the herd was 31.01% as compared to 17.34% in farms where there were no cats. Access of dogs was observed in 100% of the farms...