Canine distemper virus: the early blood-brain barrier lesion

Experimental infection of gnotobiotic Beagle dogs with neurovirulent R252 canine distemper virus (CDV) resulted in hematogenous dissemination of virus to the central nervous system (CNS). Viral antigen was first detected within CNS capillary and venular endothelia and/or perivascular astrocytic foot processes and pericytes. The number of primary infection sites was evenly distributed throughout the neuraxis. Leukocytic infiltrations followed CNS endothelial cell infection by 1-2 days and were composed of both viral antigen-positive and -negative cells. These results indicate that CDV infection of the CNS is initiated by the interaction of circulating infectious virus with endothelial cells.

Scrapie prion proteins are synthesized in neurons

Scrapie is a slow degenerative encephalopathy of animals caused by unusual infectious particles termed prions. A cDNA encoding the only apparent component of the prion, a protein designated PrP 27-30, has recently been cloned and sequenced. By measuring mRNA levels using in situ hybridization with the PrP cDNA, the authors found that prion proteins are synthesized almost exclusively within neurons. The levels of PrP mRNA varied among different types of neurons, but did not change during scrapie infection. A cDNA encoding glial fibrillary acidic protein (GFAP) was a positive control; GFAP mRNA was confined to astrocytes. Our finding of PrP mRNA in neurons may explain the degeneration and vacuolation that occurs in these cells during scrapie infection.

In vivo and in vitro models of demyelinating disease: JHM virus in the rat central nervous system localized by in situ cDNA hybridization and immunofluorescent microscopy

In situ probing of central nervous system (CNS) tissues has made it possible to associate the presence of JHM virus (JHMV) RNA with individual cells in the rat CNS. The presence of viral RNA was not always associated with antigen expression. The in situ hybridization revealed that cerebellar Purkinje cells and hippocampal neurons were highly susceptible to JHMV infection during either acute or paralytic disease. In the paralytic disease, Purkinje cell neurons frequently contained viral RNA. This observation suggests that these neurons, and perhaps others, may be repositories for JHMV in rats that undergo prolonged infections.

Differences in cell-to-cell spread of pathogenic and apathogenic rabies virus in vivo and in vitro

Pathogenic parental rabies virus and apathogenic variant virus were shown to differ in their ability to infect neurons in vivo and neuroblastoma cells in vitro. After intracerebral inoculation, the distribution of infected neurons in the brain was similar for both viruses, but the rate of spread throughout the brain, the number of infected neurons, and the degree of cellular necrosis were much lower in the case of apathogenic virus. After adsorption to mouse neuroblastoma cells, apathogenic virus was less rapidly internalized than pathogenic virus, and cell-to-cell spread of apathogenic variant virus was completely prevented by the addition of rabies virus-neutralizing antibody, whereas the spread of pathogenic virus was not affected.

Rabies virus in different segments of brain and spinal cord of naturally and experimentally infected dogs

In order to determine the presence of rabies virus in different segments of Central nervous system (CNS) of rabid animals, 31 naturally infected dogs and 6 experimentally injected ones by masseter inoculation were studied by means of Fluorescent Antibody (FA) technique and mouse intracerebral inoculation (MI) test. In the naturally infected group, the positivity by FA technique was 100.0% for the segments of Ammon's horn, cerebellum, bulb and for cervical, lumbar and sacral cord and 96.7%; for thoracic cord. Mouse inoculation test of corresponding materials was 100.0% positive for Ammon's horn, cerebellum, bulb and lumbar cord; 96.7% for cervical cord; and 93.5% for sacral cord. All examined segments of experimentally infected animals were 100.0% positive for both FA and MI tests. No clear-cut relationship could be found between the site of virus inoculation and the presence of the virus in the spinal cord. The results presented in this paper corroborate previous suggestions for the use of the spinal cord as one of the alternative laboratory diagnostic specimens for the canine rabies diagnosis.

Viral persistence and abnormalities of the central nervous system after congenital infection of sheep with border disease virus

Lambs congenitally infected with border disease (BD) virus and sheep exposed to BD virus as adults were studied for one year to determine the pathogenesis of congenital exposure compared with adult exposure to the virus. Persistent BD virus was isolated in tissue culture and detected by immunofluorescence of the peripheral white blood cells, urine, and cerebrospinal fluid of lambs with congenital BD up to one year of age. These animals had no detectable serum neutralizing antibody response to the virus for the same interval. BD virus antigen was also detected by immunofluorescence in many central nervous system tissues of these lambs with congenital BD. Dysmyelination and glial proliferation in the central nervous system and microencephaly were noted in the lambs with congenital BD, and these lesions appeared to remain the same over a 12-month period.

Localization and persistence of spiroplasmas in an experimental brain infection in suckling rats

The GT-48 strain of Spiroplasma mirum was employed in an experimental brain infection in 1-day old suckling rats in order to define the localization and persistence of organisms in brain and spleen and to evaluate the responses of three distinct genetic lines of rats. Rat pups inoculated intracerebrally with 30-300 organisms exhibited peak infections at 15-20 days post-inoculation, while challenge levels of 3-30 organisms showed some persistent infections for as long as 60 days. The responses of three genetic lines of rats to the experimental spiroplasma infection did not differ significantly over a 60-day follow-up period. The acute-phase infection in suckling rats showed a rapidly developing and widespread dissemination of organisms to all major areas of the brain.

Ultrastructural localization of viral antigens in the CNS of mice persistently infected with lymphocytic choriomeningitis virus (LCMV)

Lymphocytic choriomeningitis virus (LCMV) produces a persistent infection of the nervous system in susceptible mice. To map the localization of viral antigens in the central nervous system (CNS), the authors studied, by means of ultrastructural immune peroxidase techniques, 4-6-month-old mice persistently infected with LCMV following an intracerebral inoculation at birth. The greatest number of infected neurons was observed in the cortex, particularly of the limbic system, and certain nuclei of the hypothalamus. In the cerebellum, Purkinje cells selectively expressed viral antigens. Moderate numbers of infected neurons were found in the anterior horns of the spinal cord, basal ganglia, and thalamus. The immunoperoxidase technique using monoclonal antibodies showed that persistently infected neurons primarily expressed the nucleocapsid protein antigens of LCMV. Glycopeptide antigens were minimally expressed. Electron-microscopic examination of selected individual infected neurons showed viral antigens exclusively associated with ribosomes. No staining was seen on cell surfaces. Glutaraldehyde-fixed CNS tissue studied by electron microscopy did not reveal morphologic abnormalities or mature viral particles. This study demonstrates that LCMV persistently infects specific neuronal populations. Infected neurons express viral antigens in association with host ribosomes and show no significant morphologic alterations.

Use of cerebellar brain smears in the diagnosis of babesiosis (Babesia bovis) in cattle

Cerebral and cerebellar smears were made from 4 animals acutely reacting to Babesia bovis and 94 animals free from clinical babesiosis. The brain smears were stained by the Giemsa method and examined for the presence of B. bovis parasites. In animals showing clinical babesiosis capillaries congested with parasitised erythrocytes were abundant in cerebral and cerebellar smears. Results obtained from both types of brain smears in animals free from clinical babesiosis agreed closely (83% conformity) as to the presence or absence of parasites. A third group of 39 animals from which cerebral and cerebellar smears were taken was also examined serologically by the indirect immunofluorescent antibody test (IFAT); about 69% of the IFAT positive and doubtful animals showed parasites in the cerebellar brain smears. The existence of false negatives in the IFAT test has been shown and discussed. It has been concluded that cerebellar samples obtained through the foramen occipitale can be used for the microscopic detection of B. bovis parasites in latently infected bovines. This method can also be used in field cases suspected of cerebral babesiosis permitting brain sampling without resorting to the opening of the skull. Such an approach might prove particularly useful in areas where rabies occurs and the animal's head has to be sent to a diagnostic centre.

Binding of herpes simplex virus to regional areas of the rodent brain

The binding of 3H-thymidine labeled herpes simplex virus to homogenates of rodent brain regions and liver was examined. The results indicated that binding sites in the brain are distributed in a non-uniform manner, the specific pattern observed depending upon the age of the animal. In addition, binding was found to be reduced by pretreatment of the labeled virus with specific antiserum or trypsin. These results suggest that the distribution of herpes simplex virus receptors is one of the factors determining neurotropism and the localization of infection within the brain.

Disseminated aspergillosis occurring in patients with respiratory, renal, and hepatic failure

Respiratory, renal, and hepatic insufficiency developed in five patients who had been admitted to hospital for a variety of reasons. Although in four cases Aspergillus had been isolated from tracheal secretions before death, the significance of this finding was not fully appreciated, and in all five the diagnosis of aspergillosis was made at necropsy. Since treatment has to be started early if it is to be effective, patients with any combination of respiratory, renal, and hepatic failure should have their tracheal secretions examined daily. If Aspergillus is cultured, and hyphae are present in a fresh smear, and the patient has features of a generalised infection without an obvious site of infection, treatment for aspergillosis should be considered.

The growth of four human and animal enteroviruses in the central nervous systems of mice

The pattern of CNS infection of our enteroviruses, Coxsackievirus A14, encephalomyocarditis (EMC) virus, GDVII virus, and Vilyuisk virus, was investigated. The regional sites of virus replication were correlated with pathological changes. These viruses were found to replicate and produce similar lesions in selected sites in the mouse CNS during acute infection. Virus antigen and histological lesions were essentially confined to the gray matter, with additional but less direct support for this being provided by virus assay of CNS regions. Virus antigen only could be confidently identified in neurons, and, histologically, neurons were observed in various stages of degeneration. The distribution of the involvement varied in the different infections. For example, EMC virus infection primarily affected the cerebral hemispheres and thalamus, while Coxsackievirus a14 infection predominantly involved the brainstem and spinal cord. GDVII and Vilyuisk virus infections more uniformly involved the entire neuraxis. There was no evidence of virus replication in the olfactory bulbs, leptomeninges, ependyma, choroid plexus, and vascular endothelium. The cerebellum was generally spared, with the cerebellar hemispheres affected only in Coxsackievirus A14 infection. It therefore appears that enteroviruses selectively infect different populations of nerve cells.

Single-site localization of rabies virus: impact on laboratory reporting policy

Information accumulated by our rabies laboratory during 1977-1979 was retrospectively analyzed for patterns of rabies localization in brain. Of the 1,730 specimens reported positive during that period, 37 were positive at a single site, 27 involving only the cerebellum. Therefore, we recommend that those laboratories which offer the fluorescent rabies antibody test (FRA) examine both cerebellum and hippocampus. Definitive reports based on the FRA should be offered only when both sites have been shown negative for viral particles, or when a positive result is unquestionable.

Properties of two temperature-sensitive Rous sarcoma virus transformed cerebellar cell lines

Cells from the cerebellum of 3-day-old BD-IX rats were obtained as permanent lines by transforming them with temperature-sensitive Rous sarcoma virus. The presence or absence of veratridine-stimulated Na+-uptake (voltage-dependent channels) was used to operationally classify them as neuronal or glial. When incubated at 34 degrees C, the permissive temperature for transformation, the cerebellar cells exhibit a transformed phenotype determined by anchorage independence, rounded morphology, high growth rate and absence of density-dependent inhibition of growth. In contrast, when the transformed cerebellar cell lines are kept at a temperature (38 degrees C) non-permissive for transformation, they exhibit a normal cellular phenotype with respect to the above properties. Moreover, changes toward neuronal morphology, increase in veratridine-stimulated Na+-uptake, decreased growth rate and the expression of the astrocyte specific protein, glial fibrillary acidic protein, suggest that a degree of differentiation is expressed at the non-permissive temperature.

Light-microscopical diagnosis of rabies. A reappraisal

The validity of reports suggesting that Lyssa and Negri bodies are non-specific in the light-microscopical diagnosis of rabies was investigated. With Seller's impression technique, a substantial proportion of speciments found to be non-rabid with the fluorescent-antibody technique showed structures indistinguishable from Lyssa or Negri bodies. Neither histological examination nor inoculation of animals with non-rabid Seller-positive material explained the nature of these rabies-like structures. The simplicity and reliability of the fluorescent-antibody technique and the occasional serious complications of prophylactic anti-rabies measures make the diagnostic use of Seller's method at best undesirable and at worst dangerous.

Solid-phase radioimmunossay for rapid detection and identification of western equine encephalomyelitis virus

A solid-phase radioimmunoassay technique was adapted for the rapid detection and identification of western equine encephalomyelitis virus in clinical specimens.

Acute encephalopathy caused by defective virus infection. I. Studies of Newcastle disease virus infections in newborn and adult mice

An acute encephalopathy caused by a defective paramyxovirus infection was studied. Newcastle disease virus (ndv), given intracerebrally, caused neurologic disease and death in mice. Infected newborn mice died by the fourth day after inoculation, and abundant amounts of virus were recovered from their brains. Infected 4-week-old mice died by the eighth day, but only minimal amounts of virus, if any, were recovered. The brains of many moribund 4-week-old mice were histologically normal and contained no NDV antigen on fluorescent antibody staining. No serum antibody to NDV was detected. These features make this infection difficult to distinguish from a metabolic encephalopathy.

Growth of measles virus in nervous tissues. III. Neurovirulence of SSPE virus in ferrets

The Niigata-1 strain isolated from a patient with subacute sclerosing panencephalitis (SSPE) was inoculated intracerebrally into ferrets. Neurological signs developed in about 1 week in most of the animals. Histopathological examinations of the central nervous tissues revealed degenerative lesions in the parenchyma of the brains and inflammatory reactions predominantly in the meninges and choroid plexus. Virus antigen was demonstrated mainly in the nerve cells by immunofluorescent staining. The results indicated high affinity of the Niigata-1 strain to the nerve cells. In contrast, the Mantooth strain of SSPE virus in cell-free state did not exhibit neurovirulence in ferrets.

Early sterile autopsy in etiological studies on multiple sclerosis

The clinical findings and course in the first 2 cases of multiple sclerosis are described, in whom it was possible to isolate a virus from brain tissue by early sterile autopsy and fusion technique. It is noteworthy that in one of these cases multiple sclerosis probably occurred in female members of the family through three consecutive generations. A report is made on an additional case, in which no virus could be isolated, but in which electron microscopic studies showed two types of virus particles: nucleocapsid-like structures and particles identical in form and size with papova virus. Electron microscopic findings and attempts to cultivate a virus in multiple sclerosis published by other authors are discussed. It is pointed out, that the results described provide as yet no proof for the viral etiology of multiple sclerosis. They support the hypothesis, however, that a virus may play an essential role in the etiology and/or pathogenesis of this disease. Problems in relation to brain autopsy in multiple sclerosis are discussed. Early sterile autopsy is considered the most practicable possibility for obtaining tissue material for culturing and for ultrastructural studies in multiple sclerosis.