Do canine parvoviruses affect canine neurons? An immunohistochemical study

In cats (most of which died from panleukopenia), cerebral neurons have recently been shown to be susceptible to canine parvovirus infection. In addition to positive immunostaining and distinct in situ hybridization signals, signs of neurodegeneration were identified by histopathology, mainly in the diencephalic area. Similar histological lesions of the diencephalic regions in dogs have also attracted attention; therefore, an immunohistochemical study was initiated to determine the possible infection of canine neurons with canine parvoviruses. The study was carried out on formalin-fixed and paraffin-embedded brain tissue, with and without signs of neurodegeneration, from 40 dogs, most of them dying from parvovirus enteritis. Immunohistochemistry, using polyclonal antiserum against canine parvoviruses, was negative in all 40 cases, suggesting that, unlike cats, canine parvoviruses do not seem capable of infecting canine neurons.     

Polioencephalomalacia in the dog

Disturbance of cerebral blood flow from causes such as meningitis, thromboembolic disease and atherosclerosis was considered an important factor in the pathogenesis of polioencephalomalacia in 25 dogs. In dogs with polioencephalomalacia of undetermined cause, the distribution of lesions in neocortex and paleocortex suggested a change of neuronal metabolism secondary to cerebral anoxia/ischemia. Five dogs with canine distemper infection had bilateral necrosis of the hippocampus and pyriform cortex. Convulsions, central visual impairment and hemiparesis were the most prominent neurologic signs.     

Magnetic resonance imaging findings in histologically confirmed Pug dog encephalitis

The purpose of the study was to describe magnetic resonance (MR) imaging features of histologically confirmed necrotizing encephalitis in four Pugs and to compare those findings with MR imaging characteristics of necrotizing encephalitis in other breeds. All dogs had the following common findings: lesions restricted to the forebrain, both cerebral hemispheres diffusely but asymmetrically affected, lesions affected gray and white matter resulting in loss of distinction between both, most severe lesions in occipital and parietal lobes, lesions were irregularly T2-hyperintense and T1-isointense to slightly T1-hypointense, and no cavitation. There were various degrees of contrast enhancement of brain and leptomeninges. Asymmetry of lateral ventricles and midline shift was seen in one dog each. Two dogs had brain herniation, which may have contributed to the progression of neurologic signs. Hyperintensity on T2-weighted and fluid attenuated inversion recovery images in the hippocampus and piriform lobe was consistent with excitotoxic edema, whereas similar imaging features in other forebrain areas corresponded to areas of inflammation or liquefaction on histopathology. In comparison with necrotizing encephalitis in other canine breeds, Pug dog encephalitis has some unique MR imaging features. Therefore, these characteristics cannot be applied to other breeds, nor should imaging features of necrotizing encephalitis of other canine breeds be used for interpretation of MR images in Pug dogs.     

替来他明诱导大鼠中枢JUN核蛋白表达的研究

通过检测替来他明诱导大鼠中枢神经系统JUN核蛋白的表达,了解替来他明在中枢神经系统的作用部位,探讨替来他明对中枢神经系统的作用机制。72只SD大鼠,随机分为生理盐水组、给药后10、30、60、90、100、120、180min组,每组9只。腹腔注射替来他明50mg／kg后,分别于给药前（生理盐水组）和给药后10、30、60、90、100、120、180min经4％多聚甲醛（0．1mol／L,PB,pH7．4）灌注后,取脑,将脑分为大脑皮层、海马、丘脑、小脑、脑干等5个脑区置于20％蔗糖溶液中24h（4℃）脱水。冰冻切片,片厚10μm。免疫组织化学法（Elivision法）检测JUN核蛋白,统计各组大鼠脑片的JUN免疫反应阳性神经元的分布。对照组中仅发现少量JUN核蛋白,试验组中JUN核蛋白在大脑皮层、海马、丘脑、小脑、脑干内都有表达。替来他明腹腔注射10min后JUN核蛋白表达开始增加,60min表达至高峰,90min表达下降,180min下降至基线水平,与给药前相比无显著性差异（P〉0．05）。替来他明能诱导大鼠大脑皮层、海马、丘脑、小脑、脑干c-iun基因的表达,大脑皮层、海马、丘脑、小脑和脑干是替来他明的作用位点。     

Response of mink, skunk, red fox and raccoon to inoculation with mink virus enteritis, feline panleukopenia and canine parvovirus and prevalence of antibody to parvovirus in wild carnivores in Ontario.

Mink virus enteritis, feline panleukopenia and canine parvovirus-2 were inoculated separately into groups of raccoon, mink, red fox and striped skunk. Raccoons were highly susceptible to mink virus enteritis and feline panleukopenia, with animals developing clinical illness, and several dying within six to ten days of inoculation with lesions typical of parvovirus infection. Both viruses were shed in high titre in the feces of infected raccoons, and high antibody titres were stimulated. Raccoons inoculated with canine parvovirus-2 showed no signs; shedding of virus was sporadic though moderate titres of antibody developed. Mink inoculated with mink virus enteritis and feline panleukopenia developed signs and lesions of early parvovirus infection. No signs or significant lesions followed canine parvovirus-2 inoculation. Shedding of virus was heavy (mink virus enteritis) or sporadic (feline panleukopenia and canine parvovirus-2), though good serological responses were elicited to all three viruses. Red fox showed no signs of infection, shed all three viruses only sporadically, and the serological response was strong only to feline panleukopenia. Skunks developed low antibody titres, but no signs, and did not shed virus. Antibody to parvovirus was found in 79.2% of 144 wild red foxes; 22.3% of 112 wild raccoons; 1.3% of 157 wild skunks and 6/7 coyotes in southern Ontario. The likely significance of these viruses to wild and captive individuals and populations of these carnivores is discussed.     

犬细小病毒基因疫苗对幼貉的免疫试验

应用已构建的pcDCPV和pIRCPVIL2重组质粒配制成疫苗,对幼貉进行免疫,并对其免疫反应进行观察。应用夹心ELISA方法检测外周血中特异性的抗细小病毒血清抗体免疫球蛋白(IgG)的水平,MTT比色法检测外周血中淋巴细胞的转化率,对基因疫苗的免疫保护进行观察。结果表明,用pcDCPV和pIRCPVIL2重组质粒免疫后的幼貉对细小病毒的攻击具有一定的保护性,为pcDCPV和pIRCPVIL2重组质粒的应用奠定了基础。     

Characterization of biological and antigenic properties of raccoon dog and blue fox parvoviruses: a monoclonal antibody study

Parvovirus isolates from blue foxes and raccoon dogs were characterized by studying their haemagglutination properties, host range in vitro and antigenic structure. In all 3 characters, raccoon dog parvovirus resembled canine parvovirus (CPV), while blue fox parvovirus was similar to mink enteritis virus (MEV). Monoclonal antibodies (MAbs) were prepared against both viruses. Raccoon dog parvovirus, while resembling CPV, had a unique antigenic site which could be specified by MAbs. The pattern of MAbs prepared against blue fox parvovirus indicated that it is a member of Type 2 MEV.     

MAGNETIC RESONANCE IMAGING AND PATHOLOGIC FINDINGS ASSOCIATED WITH NECROTIZING ENCEPHALITIS IN TWO YORKSHIRE TERRIERS

Two young adult Yorkshire terriers had neurologic signs consistent with forebrain and brainstem involvement or forebrain involvement alone. On magnetic resonance imaging studies there were asymmetric bilateral lesions mainly in the cerebral cortex, and in the diencephalon. These areas were hyperintense on T2-weighted and FLAIR images, but hypointense or isointense on T1-weighted images. Lesions had a varying degree of contrast enhancement. Areas which were isointense on T1-weighted images had no contrast enhancement or only foci of contrast enhancement. Lesions with hypointensity in T1-weighted images had no enhancement or more frequently ring-like enhancement around the lesion. Necrotizing encephalitis was confirmed pathohistologically in both dogs. The degree of contrast enhancement appeared to be related to the degree of lymphohistiocytic inflammation on histologic examination.     

A Serological Survey of Enteric Parvovirus Infections in Finnish Fur-Bearing Animals

Parvovirus infections in Finnish fur animals, i.e. ferrets, raccoon dogs, blue foxes and mink, were studied. The ferret was found to be the only insusceptible animal. Parvo enteritis of raccoon dogs, reported since 1980, has spread from East Finland to other parts of the country. A new candidate for the Parvovirus family was found to infect blue foxes. According to serologic investigations, the virus resembled feline panleukopenia virus more than canine parvovirus. Clinical signs during the infection have been mild. Annual vaccination has not eradicated mink enteritis virus on farms, but the disease has taken a subclinical form.     

Central nervous system lesions caused by canine distemper virus in 4 vaccinated dogs

We examined the cerebellum and cerebrum of 4 vaccinated dogs, 3–60-mo-old, that displayed clinical signs of canine distemper virus (CDV) infection, and died 7–40 d after developing neurologic signs. The main histologic lesions were demyelination, gliosis, meningitis, perivascular lymphocytic cuffing, and inclusion bodies. These lesions were similar in all 4 cases regardless of the time since vaccination, except that meningoencephalitis and gliosis were subacute in 3 dogs and chronic in 1 dog. However, these differences did not appear to be related to their vaccination status. Immunohistologically, a CDV-positive immunoreaction was seen mainly in astrocytes, neurons and their axons, lymphocytes around and in the blood vessels of the pia mater and choroid plexus, ependymal cells of each ventricle, and the cells of the choroid plexus. The histologic and immunohistologic changes were similar in the cerebellum and cerebrum. The genetic characterization of the virus strains in 2 of these naturally occurring canine distemper cases confirmed that they were South American wild-type strains (Kiki and Uy251) belonging to the EU1/SA1 lineage. These strains are not included in the commercial CDV vaccines available in Uruguay.     

Sodium distribution in the bovine brain

Fatal sodium intoxication can occur in many species, including cattle, and postmortem confirmation often includes brain sodium concentration determination. Published information regarding brain sodium distribution in cattle was not found in a literature review. Our study was designed to determine whether sodium is uniformly distributed throughout the bovine brain. Eight whole bovine brains were collected from adult cattle with no neurologic signs or history suggestive of sodium intoxication, and with a non-neurologic cause of death diagnosed on gross examination. Brains were divided mid-sagittally. One hemisphere of each brain was homogenized. Subsamples were obtained from the remaining hemisphere (rostral, caudal, and dorsal cerebral cortices; brainstem, thalamus, and cerebellum). Sodium concentrations of regions and homogenates were measured by inductively coupled plasma–mass spectrometry. Data were analyzed using repeated measures ANOVA with a pairwise post-test to compare mean sodium concentration of each region to mean homogenate sodium concentration. Brain sodium was not uniformly distributed; sodium concentrations in different regions of the same brain varied somewhat unpredictably. Homogenization of an entire brain hemisphere appears to be the ideal method of sample preparation to ensure accurate brain sodium concentration measurement in adult cattle.     

Spongiform neurodegenerative disease in a Persian kitten

A congenital encephalopathy with spongiform degeneration and prominent neuronal apoptosis was observed in a 4-month-old Persian male cat with a history of depressed mental status and ataxia. On clinical examination, signs included right head tilt, ventroflexion of the head and neck, and tetraparesis. Histological examination of the central nervous system revealed multifocal, bilateral and symmetrical vacuolar degeneration of the neuropil, mainly involving the cerebellar and vestibular nuclei area, the caudal colliculi, the mesencephalic nuclei, the tegmental area and the deeper layer of the cerebral cortex. Accumulation of phosphorylated neurofilaments was detected in neuronal perikarya of the deep cortical layers, hippocampus and thalamus. Numerous pyknotic and apoptotic neurons were also observed in the cerebral cortex. These neuropathological changes differ from those observed in previous reports of spongiform degeneration of the grey matter in cats and were suggestive of a congenital neurodegenerative disease.     

Canine model of ischemic stroke with permanent middle cerebral artery occlusion: clinical and histopathological findings

The aim of the present study was to assess the clinical and histopathological findings in a canine model of ischemic stroke. Cerebral ischemic stroke was induced by middle cerebral artery occlusion in four healthy beagle dogs using silicone plugs. They showed neurological signs of forebrain dysfunction such as reduced responsiveness, head turning, circling, postural reaction deficits, perceptual deficits, and hemianopsia. These signs gradually regressed within 4 weeks without therapy. On magnetic resonance imaging, T2 hyperintensity and T1 hypointensity were found in the cerebral cortex and basal ganglia. These lesions were well-defined and sharply demarcated from adjacent brain parenchyma with a homogenous appearance. No abnormalities of the cerebrospinal fluid were observed. At necropsy, atrophic and necrotic lesions were observed in the cerebral cortex. The cerebral cortex, basal ganglia, and thalamus were partially unstained with triphenyl-tetrazolium chloride. Histopathologically, typical features of infarction were identified in cortical and thalamic lesions. This study demonstrates that our canine model resembles the conditions of real stroke patients.     

Molecular cloning and expression of the canine metallothionein-III gene.

We have isolated and determined the complete nucleotide sequence of canine metallothionein-III (MT-III) cDNA. The predicted amino acid sequence of the canine MT-III showed a high homology (93%, 87% identity) to that of human and mouse MT-III. The canine MT-III had 2 insertions relative to known mammalian MT-I and MT-II: a threonine after the 4th amino acid and a block of 6 amino acids near the carboxyl terminus. Expression of the canine MT-III mRNA was found exclusively in the central nervous system, where neurons in the olfactory bulb, hippocampus and cerebral cortex showed predominant signals.     

貉细小病毒分离鉴定及其VP2基因序列分析

本研究从山东省某貉养殖场发病貉粪便样品中分离到一株貉细小病毒(raccoon dog parvovirus,RDPV)。为了解该毒株的特性及其致病特点,对发病貉粪便处理后接种F81细胞,收获病毒液进行VP2基因序列分析、理化特性研究以及貉人工感染试验。结果显示:该分离株与RDPV参考株核苷酸同源性高达99.4%,属于犬细小病毒2型(CPV-2);对氯仿等不敏感,耐酸耐热,符合细小病毒特征;分离毒株对貉具有较强的致病力。结果表明,山东省仍存在RDPV流行且致病性有增强风险,须针对性研发RDPV疫苗,加强对RDPV流行的控制。本试验为RDPV流行病学研究提供了数据支持。     

Canine distemper virus infection among wildlife before and after the epidemic

In 2007–2008, a canine distemper virus (CDV) epidemic occurred among wild animals in Wakayama Prefecture, Japan, and many mammals, including the wild boar and deer, were infected. In this study, CDV prevalence among wild animals was surveyed before and after the epidemic. At first, an enzyme-linked immunosorbent assay (ELISA) with horseradish peroxidase-conjugated protein A/G was established to detect CDV antibodies in many mammalian species. This established ELISA was available for testing dogs, raccoons and raccoon dogs as well as virus-neutralization test. Next, a serological survey of wild mammalians was conducted, and it was indicated that many wild mammalians, particularly raccoons, were infected with CDV during the epidemic, but few were infected before and after the epidemic. On the other hand, many raccoon dogs died during the epidemic, but CDV remained prevalent in the remaining population, and a small epidemic occurred in raccoon dogs in 2012–2013. These results indicated that the epidemic of 2007–2008 may have been intensified by transmission to raccoons.     

Homozygous PPT1 Splice Donor Mutation in a Cane Corso Dog With Neuronal Ceroid Lipofuscinosis

A 10‐month‐old spayed female Cane Corso dog was evaluated after a 2‐month history of progressive blindness, ataxia, and lethargy. Neurologic examination abnormalities indicated a multifocal lesion with primarily cerebral and cerebellar signs. Clinical worsening resulted in humane euthanasia. On necropsy, there was marked astrogliosis throughout white matter tracts of the cerebrum, most prominently in the corpus callosum. In the cerebral cortex and midbrain, most neurons contained large amounts of autofluorescent storage material in the perinuclear area of the cells. Cerebellar storage material was present in the Purkinje cells, granular cell layer, and perinuclear regions of neurons in the deep nuclei. Neuronal ceroid lipofuscinosis (NCL) was diagnosed. Whole genome sequencing identified a PPT1c.124 + 1G>A splice donor mutation. This nonreference assembly allele was homozygous in the affected dog, has not previously been reported in dbSNP, and was absent from the whole genome sequences of 45 control dogs and 31 unaffected Cane Corsos. Our findings indicate a novel mutation causing the CLN1 form of NCL in a previously unreported dog breed. A canine model for CLN1 disease could provide an opportunity for therapeutic advancement, benefiting both humans and dogs with this disorder.     

Immunohistochemical distribution of alpha B-crystallin in the cerebellum of dogs infected with canine distemper virus

The cerebella of 12 dogs infected with canine distemper virus (CDV) and those of three normal dogs were examined. The avidin-biotin-peroxidase complex technique was used to detect alphaB-crystallin (alphaB-c) immunoreactivity and immunolocalisation of the CDV antigen. CDV antigens, immunopositive astrocytes, oligodendrocytes and granular neurons were seen in both the white and grey matter of the infected dogs. In the controls, alphaB-c immunopositive glial cells were seen in the white matter and around the Purkinje cells. In dogs with distemper, alphaB-c immunoreactivity was not observed in some of the glial cells around the Purkinje cells. A significant negative correlation of P < 0.01 level was found between areas of severe demyelination and the number of alphaB-c immunopositive cells in dogs infected with CDV. Such correlation was not observed between mild and moderate demyelinating areas and alphaB-c immunostaining. The alphaB-crystallin/ total number of cells ratio was found to be significant in severely affected demyelinating areas (P < 0.05). These data indicate that there was a relationship between the degrees of CDV associated with demyelination and the level of alphaB-c expression in the glial cells.     

噻环乙胺对大鼠不同脑区内源性阿片肽含量的影响

研究噻环乙胺麻醉下大鼠不同脑区内源性阿片肽含量的变化,探讨噻环乙胺中枢麻醉作用可能的机理。Wista大鼠128只,随机抽取8只为对照组,其余大鼠随机均分为5个试验组,分别用于测定L-Enk、M-Enk、β-EP、dynA和OFQ的含量;每个试验组又随机均分为麻醉组、恢复Ⅰ组和恢复Ⅱ组3个亚组。采用酶联免疫吸附试验(ELISA)测定各脑区内源性阿片肽的含量。结果显示腹腔内注射噻环乙胺25mg·kg-1后,麻醉组大鼠大脑皮层和丘脑内L-Enk、M-Enk、β-EP和dynA含量均显著增加(P0.05或P0.01),OFQ的含量显著降低(P0.05或P0.01);海马内L-Enk、M-Enk和β-EP含量均显著增加(P0.05或P0.01),dynA和OFQ的含量均无显著变化;脑干内M-Enk、β-EP和dynA含量均显著增加(P0.05或P0.01),OFQ的含量显著降低(P0.05),L-Enk的含量无显著变化;恢复Ⅰ组和恢复Ⅱ组,上述各脑区内L-Enk、M-Enk、β-EP、dynA和OFQ的含量均恢复显著(P0.05);麻醉全过程中,小脑内5种内源性阿片肽的含量均无显著变化(P0.05)。结果提示噻环乙胺对不同脑区内源性阿片肽的影响,可能是其产生全麻作用的重要机理之一。噻环乙胺中枢麻醉作用,可能与增加大脑皮层和丘脑内L-Enk、M-Enk、β-EP和dynA,海马内L-Enk、M-Enk和β-EP和脑干内M-Enk、β-EP和dynA的含量,同时降低大脑皮层、丘脑和脑干内OFQ的含量有关。     

Cerebellar hypoplasia in three sibling cats after intrauterine or early postnatal parvovirus infection

The present report describes the case of an intrauterine or early postnatal parvovirus infection with subsequent cerebellar hypoplasia in three kittens from the same litter. Clinical examination of affected cats revealed neurologic signs indicative of cerebellar ataxia. Due to poor prognosis, animals were euthanised and submitted for necropsy. Post mortem examination demonstrated variable degrees of cerebellar hypoplasia. Histologically, brain lesions were characterised by segmental loss of the external and internal granular layer and decreased numbers of Purkinje cells. Reactive proliferation of astrocytes in the central nervous system was verified by the detection of GFAP-expressing glial cells in affected areas using immunohistochemistry. Furthermore, parvovirus antigen was detected immunohistochemically in neuronal cells of the cerebellum, but not in other parts of the brain and spinal cord or non-neuronal tissues. The present report demonstrates the usefulness of post mortem examination and detection of viral antigen by immunohistochemistry for the discrimination of neurologic disorders in feline species. Neurologic deficiencies due to cerebellar hypoplasia caused by in utero or perinatal feline parvovirus infection should be taken into consideration as differential diagnoses for ataxia in neonatal and juvenile cats.