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B Dietzschold

Publications and source records attributed to B Dietzschold.

At least 37 records · Page 2Linked to original sources
PubMed1998

Rabies virus quasispecies: implications for pathogenesis.

Passage of the mouse-adapted rabies virus strain CVS-24 (where CVS is challenge virus standard) in BHK cells results in the rapid selection of a dominant variant designated CVS-B2c that differs genotypically and phenotypically from the dominant variant CVS-N2c present in mouse-brain- or neuroblastoma-cell-passaged CVS-24. The glycoprotein of CVS-B2c has 10 amino acid substitutions compared with that of CVS-N2c. Because CVS-B2c can be reproducibly selected in BHK cells, it is likely to be a conserved minor subpopulation of CVS-24. CVS-N2c is more neurotropic in vitro and in vivo than CVS-B2c, which replicates more readily in nonneuronal cells in vitro and in vivo. These characteristics appear to be relevant to the pathogenicity of the two variants. CVS-N2c is more pathogenic for adult mice than CVS-B2c. In contrast, CVS-B2c is more pathogenic for neonatal mice. These differences in pathogenicity are reflected in the selection pattern when mixtures of CVS-N2c and CVS-B2c were used to infect neonatal and adult mice. Although CVS-N2c was highly selected in adult mice, no selection for either variant was seen in neonates, suggesting that certain aspects of development, such as maturation of the nervous and immune systems, may contribute to the selection process. We speculate that the existence of different variants within a rabies virus strain may facilitate the virus in overcoming barriers to its spread, both within the host and between species.

Age Factors↗
PubMed1998

Immunization against rabies with plant-derived antigen.

We previously demonstrated that recombinant plant virus particles containing a chimeric peptide representing two rabies virus epitopes stimulate virus neutralizing antibody synthesis in immunized mice. We show here that mice immunized intraperitoneally or orally (by gastric intubation or by feeding on virus-infected spinach leaves) with engineered plant virus particles containing rabies antigen mount a local and systemic immune response. After the third dose of antigen, given intraperitoneally, 40% of the mice were protected against challenge infection with a lethal dose of rabies virus. Oral administration of the antigen stimulated serum IgG and IgA synthesis and ameliorated the clinical signs caused by intranasal infection with an attenuated rabies virus strain.

Administration, Oral↗
PubMed1998

The specificity of rabies virus RNA encapsidation by nucleoprotein.

Rabies virus nucleoprotein (N) encapsidates negative-strand genomic RNA in vivo, and this RNA-N complex, together with the nominal viral phosphoprotein (P) and RNA polymerase (L), forms the active cytoplasmic ribonucleoprotein (RNP) complex in virus-infected cells and the RNP core in virus particles. The RNP complex is capable of initiating viral RNA transcription and replication in vivo and in vitro. To obtain insight into the events leading to the formation of the RNA-N complex, we have investigated the interaction between rabies virus N and the positive-strand leader RNA transcript. Binding studies revealed that recombinant N binds preferentially to rabies virus leader RNA and that N binding to leader RNA was 5 to 10 times stronger than to nonleader RNA. Encapsidation of leader RNA by N could be competetively inhibited by unlabeled leader RNA but not by nonleader RNA. Furthermore, N protein encapsidation of nonleader RNA but not the leader RNA was inhibited when P was simultaneously added into the encapsidation reaction, indicating that P helps confer the specificity of leader RNA encapsidation by N. The initiation signal for leader RNA encapsidation by N has been mapped to nucleotides 20-30 of the RNA sequence which is A rich. Studies with N-deletion mutants indicate that the intact N is required to encapsidate RNA, since deletion of amino acid residues from either the N- or the C-terminus of N abolishes the ability of N to encapsidate leader RNA.

Animals↗
PubMed1998

Human diploid cell culture rabies vaccine (HDCV) and purified chick embryo cell culture rabies vaccine (PCECV) both confer protective immunity against infection with the silver-haired bat rabies virus strain (SHBRV).

The demonstration of extensive differences in the antigenic makeups of the silver-haired bat rabies virus (SHBRV) and canine rabies virus (COSRV) strains raised concerns as to whether current licensed rabies vaccines are sufficiently protective against SHBRV. NIH mouse protection test results show that both the human diploid cell culture rabies vaccine (HDCV) and the purified chicken embryo cell rabies vaccine (PCECV) protected against lethal infection with SHBRV as well as the canine rabies strain COSRV. However, in this investigation, the potencies of both vaccines in mice were found to be significantly higher for COSRV than for SHBRV. The in vivo protection data are confirmed by in vitro virus neutralizing antibody (VNA) test results which demonstrate that mice immunized with HDCV or PCECV develop significantly higher VNA titres against COSRV than against SHBRV. In contrast, VNA tests of sera from individuals immunized with HDCV or PCECV showed that humans, as opposed to mice, develop significantly higher VNA titres against SHBRV than against COSRV. These data suggest that HDCV and PCECV will protect humans against infection with the silver-haired but rabies virus strain in addition to canine rabies virus strains.

Animals↗
PubMed1998

Collaboration of antibody and inflammation in clearance of rabies virus from the central nervous system.

To investigate the involvement of various cellular and humoral aspects of immunity in the clearance of rabies virus from the central nervous system, (CNS), we studied the development of clinical signs and virus clearance from the CNS in knockout mice lacking either B and T cells, CD8+ cytotoxic T cells, B cells, alpha/beta interferon (IFN-alpha/beta) receptors, IFN-gamma receptors, or complement components C3 and C4. Following intranasal infection with the attenuated rabies virus CVS-F3, normal adult mice of different genetic backgrounds developed a transient disease characterized by loss of body weight and appetite depression which peaked at 13 days postinfection (p.i.). While these animals had completely recovered by day 21 p.i., mice lacking either B and T cells or B cells alone developed a progressive disease and succumbed to infection. Mice lacking either CD8+ T cells, IFN receptors, or complement components C3 and C4 showed no significant differences in the development of clinical signs by comparison with intact counterparts having the same genetic background. However, while infectious virus and viral RNA could be detected in normal control mice only until day 8 p.i., in all of the gene knockout mice studied except those lacking C3 and C4, virus infection persisted through day 21 p.i. Analysis of rabies virus-specific antibody production together with histological assessment of brain inflammation in infected animals revealed that clearance of CVS-F3 by 21 days p.i. correlated with both a strong inflammatory response in the CNS early in the infection (day 8 p.i.), and the rapid (day 10 p.i.) production of significant levels of virus-neutralizing antibody (VNA). These studies confirm that rabies VNA is an absolute requirement for clearance of an established rabies virus infection. However, for the latter to occur in a timely fashion, collaboration between VNA and inflammatory mechanisms is necessary.

Animals↗
PubMed1997

Failure to detect Borna disease virus infection in peripheral blood leukocytes from humans with psychiatric disorders.

The presence of antibodies reactive with Borna disease virus (BDV) in the sera of some patients with certain psychiatric illnesses has been taken as evidence that this veterinary neurotrophic virus may occasionally infect and cause psychiatric disorders in humans. In this paper, we report the results of our studies concerning the detection of BDV-specific RNA in blood cells from patients with psychiatric diseases. Contrary to the results obtained by others, we have found no evidence for the presence of BDV-RNA in such cells. Prior work with BDV sequences in the assay environment, together with the exquisite sensitivity of RT-PCR, may account for the sporadic appearance of false positive evidence that BDV-specific RNA is present in human blood cells.

Adult↗
PubMed1996

Intrinsic responses to Borna disease virus infection of the central nervous system.

Immune cells invading the central nervous system (CNS) in response to Borna disease virus (BDV) antigens are central to the pathogenesis of Borna disease (BD). We speculate that the response of the resident cells of the brain to infection may be involved in the sensitization and recruitment of these inflammatory cells. To separate the responses of resident cells from those of cells infiltrating from the periphery, we used dexamethasone to inhibit inflammatory reactions in BD. Treatment with dexamethasone prevented the development of clinical signs of BD, and the brains of treated animals showed no neuropathological lesions and a virtual absence of markers of inflammation, cell infiltration, or activation normally seen in the CNS of BDV-infected rats. In contrast, treatment with dexamethasone exacerbated the expression of BDV RNA, which was paralleled by a similarly elevated expression of mRNAs for egr-1, c-fos, and c-jun. Furthermore, dexamethasone failed to inhibit the increase in expression of mRNAs for tumor necrosis factor alpha, macrophage inflammatory protein 1 beta, interleukin 6, and mob-1, which occurs in the CNS of animals infected with BDV. Our findings suggest that these genes, encoding transcription factors, chemokines, and proinflammatory cytokines, might be directly activated in CNS resident cells by BDV. This result supports the hypothesis that the initial phase of the inflammatory response to BDV infection in the brain may be dependent upon virus-induced activation of CNS resident cells.

Animals↗
PubMed1996

Characterization of a unique variant of bat rabies virus responsible for newly emerging human cases in North America.

The silver-haired bat variant of rabies virus (SHBRV) has been identified as the etiological agent of a number of recent human rabies cases in the United States that are unusual in not having been associated with any known history of conventional exposure. Comparison of the different biological and biochemical properties of isolates of this virus with those of a coyote street rabies virus (COSRV) revealed that there are unique features associated with SHBRV. In vitro studies showed that, while the susceptibility of neuroblastoma cells to infection by both viruses was similar, the infectivity of SHBRV was much higher than that of COSRV in fibroblasts (BHK-21) and epithelial cells (MA-104), particularly when these cells were kept at 34 degrees C. At this temperature, low pH-dependent fusion and cell-to-cell spread of virus is seen in BHK-21 cells infected with SHBRV but not with COSRV. It appears that SHBRV may possess an unique cellular tropism and the ability to replicate at lower temperature, allowing a more effective local replication in the dermis. This hypothesis is supported by in vivo results which showed that while SHBRV is less neurovirulent than COSRV when administered via the intramuscular or intranasal routes, both viruses are equally neuroinvasive if injected intracranially or intradermally. Consistent with the above findings, the amino acid sequences of the glycoproteins of SHBRV and COSRV were found to have substantial differences, particularly in the region that contains the putative toxic loop, which are reflected in marked differences in their antigenic composition. Nevertheless, an experimental rabies vaccine based on the Pittman Moore vaccine strain protected mice equally well from lethal doses of SHBRV and COSRV, suggesting that currently used vaccines should be effective in the postexposure prophylaxis of rabies due to SHBRV.

Animals↗
PubMed1996

Pathogenesis of influenza virus-induced pneumonia: involvement of both nitric oxide and oxygen radicals.

The role of nitric oxide (NO) in the pathogenesis of influenza virus-induced pneumonia in mice was investigated. Experimental influenza virus pneumonia was produced with influenza virus A/Kumamoto/Y5/67(H2N2). Both the enzyme activity of NO synthase (NOS) and mRNA expression of the inducible NOS were greatly increased in the mouse lungs; increases were mediated by interferon gamma. Excessive production of NO in the virus-infected lung was studied further by using electron spin resonance (ESR) spectroscopy. In vivo spin trapping with dithiocarbamate-iron complexes indicated that a significant amount of NO was generated in the virus-infected lung. Furthermore, an NO-hemoglobin ESR signal appeared in the virus-infected lung, and formation of NO-hemoglobin was significantly increased by treatment with superoxide dismutase and was inhibited by N(omega)-monomethyl-L-arginine (L-NMMA) administration. Immunohistochemistry with a specific anti-nitrotyrosine antibody showed intense staining of alveolar phagocytic cells such as macrophages and neutrophils and of intraalveolar exudate in the virus-infected lung. These results strongly suggest formation of peroxynitrite in the lung through the reaction of NO with O2-, which is generated by alveolar phagocytic cells and xanthine oxidase. In addition, administration of L-NMMA resulted in significant improvement in the survival rate of virus-infected mice without appreciable suppression of their antiviral defenses. On the basis of these data, we conclude that NO together with O2- which forms more reactive peroxynitrite may be the most important pathogenic factors in influenza virus-induced pneumonia in mice.

Animals↗
PubMed1996

Inhibition of rabies virus infection by an oligodeoxynucleotide complementary to rabies virus genomic RNA.

To develop antirabies virus-specific agents, eight oligodeoxynucleotides (ODN) complementary to either rabies virus genomic RNA (negative polarity) or rabies virus transcripts (mRNA) were synthesized and tested for their activity to inhibit rabies virus infection in cell cultures. It was found that the ODN RH+1 complementary to rabies virus genomic RNA blocked almost completely rabies virus infection at concentrations as low as 2 microM, whereas ODN complementary to viral transcripts did poorly even at concentrations as high as 20 microM. The antigenomic ODN also has the ability to inhibit cell-to-cell spread of rabies virus, which is an indicator for protection of rabies virus infection in vivo. These results indicate that ODN complementary to rabies virus genomic RNA have strong ability to inhibit rabies virus infection in cell culture and may have the potential to be used for therapy in clinical rabies.

Animals↗
PubMed1995

Local nitric oxide production in viral and autoimmune diseases of the central nervous system.

Because of the short half-life of NO, previous studies implicating NO in central nervous system pathology during infection had to rely on the demonstration of elevated levels of NO synthase mRNA or enzyme expression or NO metabolites such as nitrate and nitrite in the infected brain. To more definitively investigate the potential causative role of NO in lesions of the central nervous system in animals infected with neurotropic viruses or suffering from experimental allergic encephalitis, we have determined directly the levels of NO present in the central nervous system of such animals. Using spin trapping of NO and electron paramagnetic resonance spectroscopy, we confirm here that copious amounts of NO (up to 30-fold more than control) are elaborated in the brains of rats infected with rabies virus or borna disease virus, as well as in the spinal cords of rats that had received myelin basic protein-specific T cells.

Amino Acid Oxidoreductases↗
PubMed1995

Expression of C1q, a subcomponent of the rat complement system, is dramatically enhanced in brains of rats with either Borna disease or experimental allergic encephalomyelitis.

In situ hybridization, RT-PCR and Northern blot analysis as well immunohistochemistry were used to examine the expression of C1q, a subcomponent of the rat complement system, in brains of rats infected with Borna disease virus (BDV) and rats afflicted with experimental allergic encephalomyelitis (EAE) induced by the adoptive transfer of myelin basic protein specific T cells. C1q mRNA, which was not detected in normal brain, became clearly detectable using RT-PCR analysis by d14 post infection (p.i.) with BDV. Maximal levels of C1q mRNA were reached 21 days p.i. when inflammatory reactions in the brain were also at a peak. Similarly, C1q mRNA was elevated when the clinical symptoms of EAE became evident 5 days following cell transfer. C1q positive cells, as identified by immunohistology, were preferentially localized in grey and white matter of the hippocampus and basolateral cortex. The C1q positive cells resembled microglial cells in morphology. The correlation of C1q expression with the development of neurological disease as well as the dramatic increase of C1q within brain regions with inflammatory lesions suggest that local biosynthesis of C1q may play a role in the pathogenesis of Borna virus induced and autoimmune encephalomyelitis.

Animals↗
PubMed1995

Expression of the rabies virus glycoprotein in transgenic tomatoes.

We have engineered tomato plants (Lycopersicon esculentum Mill var. UC82b) to express a gene for the glycoprotein (G-protein), which coats the outer surface of the rabies virus. The recombinant constructs contained the G-protein gene from the ERA strain of rabies virus, including the signal peptide, under the control of the 35S promoter of cauliflower mosaic virus. Plants were transformed by Agrobacterium tumefaciens-mediated transformation of cotyledons and tissue culture on selective media. PCR confirmed the presence of the G-protein gene in plants surviving selection. Northern blot analysis indicated that RNA of the appropriate molecular weight was produced in both leaves and fruit of the transgenic plants. The recombinant G-protein was immunoprecipitated and detected by Western blot from leaves and fruit using different antisera. The G-protein expressed in tomato appeared as two distinct bands with apparent molecular mass of 62 and 60 kDa as compared to the 66 kDa observed for G-protein from virus grown in BHK cells. Electron microscopy of leaf tissue using immunogold-labeling and antisera specific for rabies G-protein showed localization of the G-protein to the Golgi bodies, vesicles, plasmalemma and cell walls of vascular parenchyma cells. In light of our previous demonstration that orally administered rabies G-protein from the same ERA strain elicits protective immunity in animals, these transgenic plants should provide a valuable tool for the development of edible oral vaccines.

Agrobacterium tumefaciens↗