Infection of ferrets with wild type-based recombinant canine distemper virus overwhelms the immune system and causes fatal systemic disease.

Canine distemper virus (CDV) causes systemic infection resulting in severe and often fatal disease in a large spectrum of animal host species. The virus is closely related to measles virus and targets myeloid, lymphoid, and epithelial cells, but CDV is more virulent and the infection spreads more rapidly within the infected host. Here, we aimed to study the pathogenesis of wild-type CDV infection by experimentally inoculating ferrets with recombinant CDV (rCDV) based on an isolate directly obtained from a naturally infected raccoon. The recombinant virus was engineered to express a fluorescent reporter protein, facilitating assessment of viral tropism and virulence. In ferrets, this wild type-based rCDV infected myeloid, lymphoid, and epithelial cells, and the infection resulted in systemic dissemination to multiple tissues and organs, especially those of the lymphatic system. High infection percentages in immune cells resulted in depletion of these cells both from circulation and from lymphoid tissues. The majority of CDV-infected ferrets reached their humane endpoints within 20 d and had to be euthanized. In that period, the virus also reached the central nervous system in several ferrets, but we did not observe the development of neurological complications during the study period of 23 d. Two out of 14 ferrets survived CDV infection and developed neutralizing antibodies. We show for the first time the pathogenesis of a non-adapted wild type-based rCDV in ferrets. IMPORTANCE Infection of ferrets with recombinant canine distemper virus (rCDV) expressing a fluorescent reporter protein has been used as proxy to understand measles pathogenesis and immune suppression in humans. CDV and measles virus use the same cellular receptors, but CDV is more virulent, and infection is often associated with neurological complications. rCDV strains in current use have complicated passage histories, which may have affected their pathogenesis. Here, we studied the pathogenesis of the first wild type-based rCDV in ferrets. We used macroscopic fluorescence to identify infected cells and tissues; multicolor flow cytometry to determine viral tropism in immune cells; and histopathology and immunohistochemistry to characterize infected cells and lesions in tissues. We conclude that CDV often overwhelmed the immune system, resulting in viral dissemination to multiple tissues in the absence of a detectable neutralizing antibody response. This virus is a promising tool to study the pathogenesis of morbillivirus infections.

Canine distemper virus and canine adenovirus type 1 co-infection in a free-living hoary fox (Lycalopex vetulus) from Brazil.

The present case is the first description of a co-infection with canine distemper virus (CDV) and canine adenovirus type 1 (CAdV-1) in a free-living hoary fox pup from Brazil. The animal was found and rescued with poor body condition, dehydration, incoordination, ataxia, excessive vocalization, and "blue eyes" phenomenon. Despite the efforts, euthanasia was elected due to worsening clinical signs and poor prognosis. Pathologic examination revealed a mild, acute, random, necrotizing hepatitis, acute bronchopneumonia, hydrocephalus, corneal edema with epithelium degeneration, and acidophilic intracytoplasmatic inclusion bodies in different epithelial cells types with rare syncytial. Through immunohistochemistry, CDV antigen was observed in the tongue, trachea, lungs, liver, spleen, stomach, intestine and urinary bladder. Adenovirus antigen was identified in the nucleus of scattered hepatocytes. Polymerase chain reaction and sequencing demonstrated high similarity with CAdV-1 and wild-type strain of CDV close related to Brazilian viral lineages isolated from domestic dogs. Disease surveillance in wildlife animals is essential to assess possible conservation threats and consider the implementation of mitigation or control measures.

Canine distemper virus and canine adenovirus type-2 infections in neotropical otters (Lontra longicaudis) from Southern Brazil.

All descriptions of infectious diseases affecting otters were published in the Northern Hemisphere, with no occurrence identified in neotropical otters (Lontra longicaudis). Consequently, a retrospective histopathological study using archival tissue samples from six free-living neotropical otters was done to investigate the possible occurrence of disease patterns associated with common viral infectious disease agents of the domestic dogs. Immunohistochemical (IHC) assays were designed to identify intralesional tissue antigens of canine distemper virus (CDV), and canine adenovirus-1 (CAdV-1) and canine adenovirus-2 (CAdV-2). The most frequent histopathological patterns diagnosed were interstitial pneumonia (83.33%; 6/5) and hepatocellular vacuolar degeneration (50%; 3/6). IHC identified intralesional intracytoplasmic immunoreactivity to CDV antigens in all otters evaluated, with positive immunolabeling occurring within epithelial cells of the lungs, stomach, kidneys, and liver, and skin. Intracytoplasmic CAdV-2 antigens were identified within epithelial cells of the peribronchial glands in four otters with interstitial pneumonia. These findings resulted in singular and simultaneous infections in these neotropical otters, represented the first report of concomitant infections by CDV and CAdV-2 in free-living neotropical otters from the Southern Hemisphere, and suggested that this mammalian species is susceptible to infections by viral disease agents common to the domestic dogs and may develop similar histopathologic disease patterns.

Natural Canine Distemper Virus Infection in Linnaeus's 2-Toed Sloths (Choloepus didactylus).

An outbreak of canine distemper virus in a private zoo in eastern Tennessee in July 2016 led to fatal clinical disease in 5 adult, wild-caught Linnaeus's 2-toed sloths (Choloepus didactylus). Clinical signs included hyporexia, lethargy, mucopurulent nasal discharge, and oral and facial ulcers. At necropsy, affected animals had crusts and ulcers on the lips, nose, tongue, and oral cavity. Microscopically, all sloths had widespread, random, hepatic necrosis; lymphoid depletion; and bronchointerstitial pneumonia. The central nervous system did not contain gross or histopathologic lesions in any of the 5 sloths, although immunoreactivity for viral antigen was present within vessel walls. Epithelial cells and histiocytes within numerous organs contained intranuclear and intracytoplasmic inclusions and occasional syncytial cells. Canine distemper virus was confirmed with immunohistochemistry and virus isolation. Viral sequencing identified the novel American-4 strain prevalent in eastern Tennessee wildlife. This is the first pathologic characterization of canine distemper virus infection in sloths (family Choloepodidae, order Pilosa) and emphasizes the significant morbidity and mortality in this species.

Immunohistochemical evidence of canine morbillivirus (canine distemper) infection in coatis (Nasua nasua) from Southern Brazil.

The pathological and immunohistochemical (IHC) findings associated with infection due to canine morbilivírus (canine distemper virus, CDV) are described in coatis (Nasua nasua). Tissue fragments of coatis (n = 13) that died at the Bela Vista Sanctuary, Paraná, Southern Brazil, were routinely processed for histopathology to identify the main histopathologic patterns as compared to that of the domestic dog. Selected formalin-fixed paraffin-embedded (FFPE) tissue fragments of the lungs, liver, urinary bladder and small intestine were used in IHC assays designed to identify the antigens of CDV, canine adenovirus (CAdV-1 and CAdV-2) and canine parvovirus type 2 (CPV-2). The main histopathologic patterns identified were interstitial pneumonia (n = 9), interstitial nephritis (n = 6), atrophic enteritis (n = 4) and ballooning degeneration of the uroepithelium (n = 3). Positive immunolabelling for intralesional antigens of CDV was identified in the lung with interstitial pneumonia (n = 3), in the intestine (n = 2) and in the degenerated epithelium of the urinary bladder (n = 2). Antigens of CPV-2, CAdV-1 and CAdV-2 were not identified in any FFPE tissue sections evaluated. These findings indicate that these wild carnivores were infected by a viral disease pathogen common to the domestic dog and develop similar histopathologic findings. Collectively, these findings suggest that these coatis were infected by CDV and can serve as a potential host for this infectious disease pathogen.

Persistent Morbillivirus Infection Leads to Altered Cortactin Distribution in Histiocytic Sarcoma Cells with Decreased Cellular Migration Capacity.

Histiocytic sarcomas represent rare but fatal neoplasms in humans. Based on the absence of a commercially available human histiocytic sarcoma cell line the frequently affected dog displays a suitable translational model. Canine distemper virus, closely related to measles virus, is a highly promising candidate for oncolytic virotherapy. Therapeutic failures in patients are mostly associated with tumour invasion and metastasis often induced by misdirected cytoskeletal protein activities. Thus, the impact of persistent canine distemper virus infection on the cytoskeletal protein cortactin, which is frequently overexpressed in human cancers with poor prognosis, was investigated in vitro in a canine histiocytic sarcoma cell line (DH82). Though phagocytic activity, proliferation and apoptotic rate were unaltered, a significantly reduced migration activity compared to controls (6 hours and 1 day after seeding) accompanied by a decreased number of cortactin mRNA transcripts (1 day) was detected. Furthermore, persistently canine distemper virus infected DH82 cells showed a predominant diffuse intracytoplasmic cortactin distribution at 6 hours and 1 day compared to controls with a prominent membranous expression pattern (p ≤ 0.05). Summarized, persistent canine distemper virus infection induces reduced tumour cell migration associated with an altered intracellular cortactin distribution, indicating cytoskeletal changes as one of the major pathways of virus-associated inhibition of tumour spread.

Unusual Necrotizing Encephalitis in Raccoons and Skunks Concurrently Infected With Canine Distemper Virus and Sarcocystis sp.

Canine distemper virus commonly infects free-ranging, terrestrial mesopredators throughout the United States. Due to the immunosuppressive effects of the virus, concurrent opportunistic infections are also common. Among these, secondary systemic protozoal infections have been described in a number of species. We report an unusual presentation of necrotizing encephalitis associated withSarcocystissp in four raccoons and one skunk concurrently infected with canine distemper virus. Lesions were characterized by variably sized necrotizing cavitations composed of abundant mineral admixed with inflammatory cells and protozoa.Sarcocystissp was confirmed via immunohistochemistry using a monoclonal antibody toSarcocystis neurona The pathologic changes are similar to lesions in human AIDS patients infected withToxoplasma gondii.

Pathogenesis of canine distemper virus in experimentally infected raccoon dogs, foxes, and minks.

Canine distemper virus (CDV) infects a broad range of carnivores and causes a highly contagious disease with severe immunosuppression. The disease severity markedly varies in different species. To investigate the pathogenesis of CDV in raccoon dog (Nyctereutes procyonoides), fox (Vulpes vulpes) and mink (Neovison vison) species, three groups of CDV sero-negative animals were infected with CDV strain LN(10)1. This CDV strain belongs to the Asia-1 genotype, which is epidemiologically predominant in carnivores in China. CDV infection provoked marked differences in virulence in the three species that were studied. Raccoon dogs developed fever, severe conjunctivitis, and pathological lesions, with 100% (5/5) mortality and with high viral RNA loads in organs within 15 days post infection (dpi). In infected foxes, the onset of the disease was delayed, with 40% (2/5) mortality by 21 dpi. Infected minks developed only mild clinical signs and pathological lesions, and mortality was not observed. Raccoon dogs and foxes showed more severe immune suppression (lymphopenia, decreased lymphocyte proliferation, viremia and low-level virus neutralizing antibodies) than minks. We also observed a distinct pattern of cytokine mRNA transcripts at different times after infection. Decreased IFN-γ and IL-4 mRNA responses were evident in the animals with fatal disease, while up-regulation of these cytokines was observed in the animals surviving the infection. Increased TNF-α response was detected in animals with mild or severe clinical signs. Based on the results, we could distinguish three different patterns of disease after experimental CDV infection, e.g. a mild form in minks, a moderate form in foxes and a severe disease in raccoon dogs. The observed differences in susceptibility to CDV could be related to distinct host cytokine profiles. Comparative evaluation of CDV pathogenesis in various animal species is pivotal to generate models suitable for the evaluation of CDV-host interactions and of vaccine response.

Cutaneous lesions associated with dual infection caused by canine distemper virus and orthopoxvirus in a domestic cat.

BACKGROUND: Within the context of an increased epidemiological pressure caused by canine distemper virus (CDV) in Switzerland together with a potential re-emergence of endemic pathogens such as orthopoxviruses (OPXV), dual infections are possible among susceptible species. OBJECTIVE: To describe a case of concurrent CDV and OPXV infection in a cat. ANIMAL: A 5-year-old, neutered male cat was presented with erythema, crusts and ulcerations around the left eye. High-grade pruritus and a severe conjunctivitis were also present. METHODS: Formalin-fixed skin biopsy samples were obtained from lesional skin. Histopathology, CDV immunohistochemistry and CDV and OPXV RT-PCR were performed. RESULTS: Histopathological examination showed severe epidermal necrosis extending to the follicular walls and a dermal infiltration, predominantly eosinophilic. Intranuclear and intracytoplasmic eosinophilic inclusion bodies were visible in the wall of affected hair follicles, with occasional formation of syncytia. The RT-PCR revealed the contextual presence of both CDV and OPXV. Scattered cells stained positive for CDV by immunohistochemistry. CONCLUSION AND DISCUSSION: Dual infections with CDV and OPXV, although rare, may occur and represent additional differential diagnoses for ulcerative skin lesions in cats.

Canine distemper virus: detection of viral RNA by Nested RT-PCR in dogs with clinical diagnosis / Vírus da cinomose canina: detecção do RNA viral pelo Nested RT-PCR em cães com diagnóstico clínico

Canine distemper virus (CDV) is a pathogen which affects dogs and causes severe disease leading to death. Dogs infected with CDV can be diagnosed by RNA detection by Nested PCR technique. The following study proposed to evaluate CDV RNA in blood, urine and saliva samples. The Nested-PCR technique was able to detect CDV RNA in different types of biologic samples. The higher number of positive results was obtained in urine samples.

vírus da cinomose canina (CDV) é um patógeno que afeta cães, causando doença grave e que pode levar a morte. Os cães infectados pelo CDV podem ser diagnosticados pela detecção do RNA utilizando-se a técnica de Nested-PCR. O presente estudo teve como objetivo avaliar o RNA do CDV no sangue, urina e saliva em cães com diagnóstico clínico de cinomose. A técnica de Nested-PCR foi capaz de detectar o RNA em diferentes tipos de amostras biológicas. Obteve-se um maior número de resultados positivos em amostras de urina.

Fatal canine distemper infection in a pack of African wild dogs in the Serengeti ecosystem, Tanzania.

In 2007, disease related mortality occurred in one African wild dog (Lycaon pictus) pack close to the north-eastern boundary of the Serengeti National Park, Tanzania. Histopathological examination of tissues from six animals revealed that the main pathologic changes comprised interstitial pneumonia and suppurative to necrotizing bronchopneumonia. Respiratory epithelial cells contained numerous eosinophilic intracytoplasmic inclusion bodies and multiple syncytial cells were found throughout the parenchymal tissue, both reacting clearly positive with antibodies against canine distemper virus (CDV) antigen. Phylogenetic analysis based on a 388 nucleotide (nt) fragment of the CDV phosphoprotein (P) gene revealed that the pack was infected with a CDV variant most closely related to Tanzanian variants, including those obtained in 1994 during a CDV epidemic in the Serengeti National Park and from captive African wild dogs in the Mkomazi Game Reserve in 2000. Phylogenetic analysis of a 335-nt fragment of the fusion (F) gene confirmed that the pack in 2007 was infected with a variant most closely related to one variant from 1994 during the epidemic in the Serengeti National Park from which a comparable fragment is available. Screening of tissue samples for concurrent infections revealed evidence of canine parvovirus, Streptococcus equi subsp. ruminatorum and Hepatozoon sp. No evidence of infection with Babesia sp. or rabies virus was found. Possible implications of concurrent infections are discussed. This is the first molecular characterisation of CDV in free-ranging African wild dogs and only the third confirmed case of fatal CDV infection in a free-ranging pack.

Pathogenesis and immunopathology of systemic and nervous canine distemper.

Canine distemper is a worldwide occurring infectious disease of dogs, caused by a morbillivirus, closely related to measles and rinderpest virus. The natural host range comprises predominantly carnivores. Canine distemper virus (CDV), an enveloped, negative-sense RNA virus, infects different cell types, including epithelial, mesenchymal, neuroendocrine and hematopoietic cells of various organs and tissues. CDV infection of dogs is characterized by a systemic and/or nervous clinical course and viral persistence in selected organs including the central nervous system (CNS) and lymphoid tissue. Main manifestations include respiratory and gastrointestinal signs, immunosuppression and demyelinating leukoencephalomyelitis (DL). Impaired immune function, associated with depletion of lymphoid organs, consists of a viremia-associated loss of lymphocytes, especially of CD4+ T cells, due to lymphoid cell apoptosis in the early phase. After clearance of the virus from the peripheral blood an assumed diminished antigen presentation and altered lymphocyte maturation cause an ongoing immunosuppression despite repopulation of lymphoid organs. The early phase of DL is a sequel of a direct virus-mediated damage and infiltrating CD8+ cytotoxic T cells associated with an up-regulation of pro-inflammatory cytokines such as interleukin (IL)-6, IL-8, tumor necrosis factor (TNF)-alpha and IL-12 and a lacking response of immunomodulatory cytokines such as IL-10 and transforming growth factor (TGF)-beta. A CD4+-mediated delayed type hypersensitivity and cytotoxic CD8+ T cells contribute to myelin loss in the chronic phase. Additionally, up-regulation of interferon-gamma and IL-1 may occur in advanced lesions. Moreover, an altered balance between matrix metalloproteinases and their inhibitors seems to play a pivotal role for the pathogenesis of DL. Summarized, DL represents a biphasic disease process consisting of an initial direct virus-mediated process and immune-mediated plaque progression. Immunosuppression is due to early virus-mediated lymphocytolysis followed by still poorly understood mechanisms affecting antigen presentation and lymphocyte maturation.

Marcação imunoistoquímica da expressão astrocitária de proteína glial fibrilar ácida e de vimentina no sistema nervoso central de cães com cinomose / Immunohistochemical staining of the astrocytic expression of glial fibrillary acidic protein and vimentin in the central nervous system of dogs with canine distemper

Uma vez que muitos dos aspectos envolvidos na patogenia dos processos desmielinizantes do sistema nervoso central (SNC) são ainda pouco esclarecidos e que os astrócitos parecem estar envolvidos na mediação de tais processos, este estudo analisou morfologicamente a participação astrocitária na desmielinização do SNC por meio da marcação imunoistoquímica de duas proteínas dos filamentos intermediários astrocitários - a proteína glial fibrilar ácida (GFAP) e a vimentina (VIM) -, comparando amostras de cerebelo e de tronco encefálico de oito cães com cinomose e de dois cães normais, de diferentes raças e com idades entre um e quatro anos. Cortes histológicos dos tecidos foram submetidos à marcação pelo método indireto da avidina-biotina-peroxidase (ABC) e a reatividade astrocitária, observada em microscopia de luz, foi quantificada em um sistema computacional de análise de imagens. Observou-se, na maioria dos cortes de animais doentes, a presença de lesões degenerativas compatíveis com desmielinização. A marcação para a GFAP e para a VIM foi mais intensa nos animais com cinomose do que nos animais normais, especialmente nas regiões circunventriculares e nas adjacentes às áreas de degeneração tecidual. Não houve diferença significativa entre a imunomarcação (GFAP e VIM) dos animais com cinomose com e sem infiltração inflamatória da substância branca do cerebelo. O aumento da imunorreatividade dos astrócitos para a GFAP e a reexpressão de VIM nas áreas lesionais indicam o envolvimento astrocitário na resposta do tecido nervoso às lesões desmielinizantes induzidas pelo vírus da cinomose (CDV) no SNC.

Considering that many aspects involved in the pathogenesis of the central nervous system (CNS) demyelinating diseases are still poorly understood and that astrocytes seem to mediate such processes, this study analyzed the participation of astrocytes in the demyelinating processes of CNS by using immunohistochemical staining of two astrocytic proteins - glial fibrillary acidic protein (GFAP) and vimentin (VIM) -, comparing samples of cerebellum and brainstem from eight dogs with canine distemper and from two healthy dogs, from different breeds and ages varying from 1 to 4 years old. Histological sections were submitted to the avidin-biotin-peroxidase indirect method of immmunohistochemical staining (ABC) and the astrocytic reactivity, observed in light microscopy, was quantified in a computer system for image analysis. It was possible to notice, on most of the sections from sick animals, degenerative lesions that indicate demyelination. The immunostaining for GFAP and VIM was more intense on animals with canine distemper, specially around the ventricules and near degenerated sites. There was no significant difference between the immunostaining (GFAP and VIM) of animals with canine distemper with and without inflammatory infiltrate of the cerebellar white matter. The increased immunoreactivity of astrocytes for GFAP and the VIM reexpression in injured areas indicate the astrocytic involvement on nervous tissue response to the demyelinating lesions induced by the canine distemper virus (CDV) in the CNS.

Comparison of molecular and growth properties for two different canine distemper virus clusters, Asia 1 and 2, in Japan.

To compare the molecular and growth properties of two newly isolated canine distemper virus strains in the Asia 1 and 2 groups with clinico-pathological findings in dogs, nucleotide and predicted amino acid sequence comparisons of genes H and P were performed together with comparative growth profiling. The predicted amino acid sequences of the H gene contained 12 cysteine residues that were conserved among the examined Asia 1 and Asia 2 viruses. The hydrophobic region in the H gene of the Asia 2 isolates was one amino acid longer than that of the Asia 1 group. The H gene of the Asia 1 group had nine putative asparagine (N)-linked glycosylation sites, while there were eight sites in the Asia 2 group. The titers of the cell-associated viruses for the Asia 1 strains were higher than those of the released viruses and were opposite to those of the Asia 2 strains in a previous study. The molecular and growth properties of the Asia 1 and Asia 2 groups seem to vary, although no significant differences were observed in the clinical signs and pathological findings between the two groups.

Simultaneous canine distemper virus, canine adenovirus type 2, and Mycoplasma cynos infection in a dog with pneumonia.

The present case is the first description of a triple infection with canine distemper virus (CDV), canine adenovirus (CAV) type 2, and Mycoplasma cynos in a dog. The 5-month-old female Miniature Pinscher was euthanized because of dyspnea, croaking lung sounds, weight loss, and lymphopenia. Pathologic examination revealed a fibrinous necrotizing pneumonia with large amphophilic intranuclear and acidophilic intracytoplasmatic inclusion bodies in different lung cells. Immunohistochemically, CDV antigen was present in lung and many other organs. In situ hybridization for detection of CAV nucleic acid showed positive signals in the lung only. Polymerase chain reaction of lung tissue and consecutive sequencing of the amplification product identified CAV type 2. Bacteriologic examination of lung tissue yielded large amounts of M cynos. This infection was confirmed by immunohistochemistry detecting abundant positive signals in the lung tissue.

Canine distemper virus uses both the anterograde and the hematogenous pathway for neuroinvasion.

Canine distemper virus (CDV), a member of the Morbillivirus genus that also includes measles virus, frequently causes neurologic complications, but the routes and timing of CDV invasion of the central nervous system (CNS) are poorly understood. To characterize these events, we cloned and sequenced the genome of a neurovirulent CDV (strain A75/17) and produced an infectious cDNA that expresses the green fluorescent protein. This virus fully retained its virulence in ferrets: the course and signs of disease were equivalent to those of the parental isolate. We observed CNS invasion through two distinct pathways: anterogradely via the olfactory nerve and hematogenously through the choroid plexus and cerebral blood vessels. CNS invasion only occurred after massive infection of the lymphatic system and spread to the epithelial cells throughout the body. While at early time points, mostly immune and endothelial cells were infected, the virus later spread to glial cells and neurons. Together, the results suggest similarities in the timing, target cells, and CNS invasion routes of CDV, members of the Morbillivirus genus, and even other neurovirulent paramyxoviruses like Nipah and mumps viruses.

A molecular study of hippocampus in dogs with convulsion during canine distemper virus encephalitis.

In this study, we have investigated the expression of the nuclear transcription factor (c-Fos, NFkB), growth factors (nerve growth factor--NGF, brain-derived neurotrophic factor--BDNF), peptides (enkephalin, galanin) and glutamate transporter (AA 504-523 rat EAAC1) in 6 dogs sacrificed immediately after seizure attack during encephalomyelitis due to canine distemper virus (CDV) (as assessed by clinical examination, RT-PCR and viral RNA detection either in blood or brain tissue and CDV immunohistochemistry in brain slices). In all these CDV affected dogs, the observed neurological signs included untreatable seizures, leading to cluster seizure activity and status epilepticus. In the inter-ictal phase abnormal mentation, postural and gait deficits and sometimes involuntary movements such as myoclonus were recorded. The same investigation was carried out in 5 control dogs affected by different disorders, all characterized by the absence of seizures. Brains were dissected out immediately after euthanasia and fixed; sections collected from the dorsal hippocampus were processed for immunohistochemistry. By comparing hippocampus sections obtained from dog with and without seizure, the following regulations were observed. A strong up-regulation of glutamate transporter throughout the cell layers was found together with the onset of nuclear Fos and NFkB-IR in the pyramidal cell layer X. Among the investigated peptides, we observed a slight increase in enkephalinergic fibers and a strong up-regulation of mu-opioid receptors, whereas galanin-IR seemed to be weaker. Finally, both NGF and BDNF expression was strongly up-regulated. BDNF-IR was mainly localized in the apical dendrite in pyramidal neurons. To our knowledge, these data offer the first indication that molecular events described in experimental kindling also occur during spontaneous pathology in animal species sharing close similarities to human neuropathology.

Cerebrospinal fluid from a 7-month-old dog with seizure-like episodes.

A 7-month-old dog was presented to the Veterinary Teaching Hospital of the Universidade Estadual de Londrina, Paraná, Brazil with a 1-week history of seizure-like activity and compulsive walking. Neurological deficits included seizures, nystagmus, absence of a menace reaction, depressed postural reactions, spastic tetraparesis, opisthotonos, and spasticity of the thoracic limbs. Cerebrospinal fluid (CSF) evaluation showed severe lymphocytic pleocytosis (554 cells/microL, with 70% lymphocytes) and a protein concentration of 17 mg/dL. The histopathologic findings in cerebrum, cerebellum, and brainstem obtained at necropsy were compatible with acute encephalomyelitis caused by canine distemper virus (CDV). Using reverse transcription-polymerase chain reaction (RT-PCR), CDV RNA was detected in both CSF and fragments of fresh brain tissue. The results indicated that CDV was the agent responsible for the clinical and laboratory presentation. Severe pleocytosis with lymphocyte predominance is an unusual finding in canine distemper and must be differentiated from granulomatous meningoencephalitis. RT-PCR on CSF is a useful, fast, and specific method to diagnose CDV infection in dogs.

Immunohistochemical detection of antigens of distemper, adenovirus and parainfluenza viruses in domestic dogs with pneumonia.

The lungs of 35 dogs that died in Mexico from acute or subacute pneumonia were examined immunohistochemically for canine distemper virus (CDV), canine adenovirus (CAV) and canine parainfluenza virus (CpiV), to determine their frequency and occurrence and possible associations. CDV was identified in 27 (77%) cases, CAV in 20 (57%) and CpiV in 18 (51%). The most frequent dual association was that between CDV and CpiV (five cases; 14%). All three viruses, however, were identified in the same lung in 10 cases. Immunolabelling occurred in alveolar macrophages, monocytes, pneumocytes, epithelial cells and syncytial cells. It was concluded that immunohistochemistry is a useful diagnostic tool in canine respiratory disease to complement histopathological examination.

Reduced nuclear translocation of nuclear factor (NF)-kappaB p65 in the footpad epidermis of dogs infected with distemper virus.

Infection of canine footpads with the canine distemper virus (CDV) can cause massive epidermal thickening (hard pad disease), as a consequence of increased proliferation of keratinocytes and hyperkeratosis. Keratinocytes of canine footpad epidermis containing detectable CDV nucleoprotein antigen and CDV mRNA were shown previously to have increased proliferation indices. Because various proteins that play a role in the proliferation of epidermal cells are viral targets, the potential participation of such proteins in CDV-associated keratinocyte proliferation was investigated. Transforming growth factor-alpha (TGF-alpha), cell cycle regulatory proteins p21, p27 and p53, and nuclear factor (NF)-kappaB transcription factor components p50 and p65 were studied in the footpad epidermis from the following groups of dogs inoculated with CDV: group 1, consisting of seven dogs with clinical distemper and CDV in the footpad epidermis; group 2, consisting of four dogs with clinical distemper but no CDV in the footpad epidermis; group 3, consisting of eight dogs with neither clinical distemper nor CDV in the footpad epithelium. Group 4 consisted of two uninoculated control dogs. The expression of TGF-alpha, p21, p27 and p53, and p50 in the basal layer, lower and upper spinous layers, and in the granular layer did not differ statistically between CDV-positive (group 1) and CDV-negative (groups 2-4) footpad epidermis. However, there were differences in the levels of nuclear and cytoplasmic p65 expression between group 1 dogs and the other three groups. Thus, footpads from group 1 dogs had more keratinocytes containing p65 in the cytoplasm and, conversely, fewer nuclei that were positive for p65. These findings indicate that p65 translocation into the nucleus is reduced in CDV-infected footpad epidermis. Such decreased translocation of p65 may help to explain increased keratinocyte proliferation in hard pad disease and suggests interference of CDV with the NF-kappaB pathway.