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1.
J Fu  M Rodriguez    R P Roos 《Journal of virology》1990,64(12):6345-6348
The GDVII strain and other members of the GDVII subgroup of Theiler's murine encephalomyelitis viruses (TMEV) cause an acute lethal neuronal infection in mice, whereas the DA strain and other members of the TO subgroup of TMEV cause a chronic demyelinating disease associated with a persistent virus infection. We used GDVII/DA chimeric infectious cDNAs to produce intratypic recombinant viruses in order to clarify reasons for the TMEV subgroup-specific difference in demyelinating activity. We found that both the GDVII and DA strains contain a genetic determinant(s) for demyelinating activity. No demyelination occurs following GDVII strain inoculation because this strain produces an early neuronal disease that kills mice before white matter disease and persistent infection can occur.  相似文献   

2.
The DA strain of Theiler's virus, a murine picornavirus, causes a persistent infection of glial cells of the white matter of the spinal cord, associated with chronic inflammation and primary demyelination. The GDVII strain causes an acute fatal grey matter encephalomyelitis. We characterized the target cells of GDVII and DA viruses 4 days following intracerebral inoculation, and we compared the levels of viral RNA within these cells. GDVII virus infected approximately 10 times more cells than DA virus. Whereas GDVII virus infected neurons exclusively, DA virus infected also astrocytes and possible macrophage-microglial cells. The levels of viral RNA in neurons infected with GDVII and DA viruses were of the same order. These results show that DA virus infects glial cells already at the beginning of the disease and that the more efficient spread of GDVII virus is probably not due to a higher level of RNA replication per cell.  相似文献   

3.
Theiler's murine encephalomyelitis virus (TMEV) is a natural pathogen of the mouse and belongs to the Picornaviridae family. TMEV strains are divided into two subgroups on the basis of their pathogenicity. The first group contains two neurovirulent strains, FA and GDVII, which cause a rapid fatal encephalitis. The second group includes persistent strains, like DA and BeAn, which produce a biphasic neurological disease in susceptible mice. Persistence of these viruses in the white matter of the spinal cord leads to chronic inflammatory demyelination. L929 cells, which are susceptible to TMEV infection, were subjected to physicochemical mutagenesis. Cellular clones that became resistant to TMEV infection were selected by viral infection. Three such mutants resistant to strain GDVII were characterized to determine the step of the virus cycle that was inhibited. The mutation present in one of these mutant cell lines inhibited, by more than 1,000-fold, the entry of strain GDVII but hardly decreased infection by strain DA. In the two other cellular mutants, replication of the viral genome was slowed down. Interestingly, one of these mutant cell lines resisted infection by both the persistent and neurovirulent strains while the second cell line resisted infection by strain GDVII but remained susceptible to the persistent virus. These results show that although they have 95% identity at the amino acid sequence level, neurovirulent and persistent viruses use partly distinct pathways for both entry into cells and genome replication.  相似文献   

4.
L Zhou  X Lin  T J Green  H L Lipton    M Luo 《Journal of virology》1997,71(12):9701-9712
Theiler's murine encephalomyelitis viruses (TMEVs) belong to the Picornaviridae family and are divided into two groups, typified by strain GDVII virus and members of the TO (Theiler's original) group. The highly virulent GDVII group causes acute encephalitis in mice, while the TO group is less virulent and causes a chronic demyelinating disease which is associated with viral persistence in mice. This persistent central nervous system infection with demyelination resembles multiple sclerosis (MS) in humans and has thus become an important model for studying MS. It has been shown that some of the determinants associated with viral persistence are located on the capsid proteins of the TO group. Structural comparisons of two persistent strains (BeAn and DA) and a highly virulent strain (GDVII) showed that the most significant structural variations between these two groups of viruses are located on the sites that may influence virus binding to cellular receptors. Most animal viruses attach to specific cellular receptors that, in part, determine host range and tissue tropism. In this study, atomic models of TMEV chimeras were built with the known structures of GDVII, BeAn, and DA viruses. Comparisons among the known GDVII, BeAn, and DA structures as well as the predicted models for the TMEV chimeras suggested that a gap on the capsid surface next to the putative receptor binding site, composed of residues from VP1 and VP2, may be important in determining viral persistence by influencing virus attachment to cellular receptors, such as sialyloligosaccharides. Our results showed that sialyllactose, the first three sugar molecules of common oligosaccharides on the surface of mammalian cells, inhibits virus binding to the host cell and infection with the persistent BeAn virus but not the nonpersistent GDVII and chimera 39 viruses.  相似文献   

5.
6.
Theiler's murine encephalomyelitis virus (TMEV) is a natural pathogen of the mouse. The different strains of TMEV are divided into two subgroups according to the pathology they provoke. The neurovirulent strains GDVII and FA induce an acute fatal encephalitis, while persistent strains, like DA and BeAn, cause a chronic demyelinating disease associated with viral persistence in the central nervous system. Different receptor usage was proposed to account for most of the phenotype difference between neurovirulent and persistent strains. Persistent but not neurovirulent strains were shown to bind sialic acid. We characterized DA and GDVII derivatives adapted to grow on CHO-K1 cells. Expression of glycosaminoglycans did not influence infection of CHO-K1 cells by parental and adapted viruses. Mutations resulting from adaptation of DA and GDVII to CHO-K1 cells notably mapped to the well-characterized VP1 CD and VP2 EF loops of the capsid. Adaptation of the DA virus to CHO-K1 cells correlated with decreased sialic acid usage for entry. In contrast, adaptation of the GDVII virus to CHO-K1 cells correlated with the appearance of a weak sialic acid usage for entry. The sialic acid binding capacity of the GDVII variant resulted from a single amino acid mutation (VP1-51, Asn-->Ser) located out of the sialic acid binding region defined for virus DA. Mutations affecting tropism in vitro and sialic acid binding dramatically affected the persistence and neurovirulence of the viruses.  相似文献   

7.
The strains of Theiler’s murine encephalomyelitis virus, a picornavirus, are divided into two groups according to their neurovirulence after intracerebral inoculation. The highly virulent GDVII strain causes an acute, fatal encephalomyelitis, whereas the DA strain causes a mild encephalomyelitis followed by a chronic inflammatory demyelinating disease associated with viral persistence. Studies with recombinant viruses showed that the capsid plays the major role in determining these phenotypes. However, the molecular basis for the effect of the capsid on neurovirulence is still unknown. In this paper, we describe a large difference in the patterns of infection of primary neuron cultures by the GDVII and DA strains. Close to 90% of the neurons were infected 12 h after inoculation with the GDVII strain, and the cytopathic effect was complete 24 h postinoculation. In contrast, with the DA strain, viral antigens were not detected in neurons until 24 h postinoculation. Infected neurons accounted for only 2% of the total number of neurons, even 6 days after inoculation. No cytopathic effect was visible, and the cultures could be kept for the same length of time as the noninfected controls. Because the neurovirulence of the GDVII strain has been mapped to the capsid, we examined the role of the capsid in this difference of phenotype. We showed, using recombinant viruses, that the capsid was indeed responsible for the pattern of infection observed in vitro, most likely through its role in viral entry. Thus, the levels of neurovirulence of the GDVII and DA strains correlate with their abilities to infect cultured neurons, and this ability is controlled by the capsid.  相似文献   

8.
Theiler's murine encephalomyelitis viruses (TMEV) are serologically related picornaviruses which cause both enteric and neurological disease in mice. The biological activities of TMEV vary between the two different TMEV subgroups (TO and GDVII) and with different passage histories of the same TMEV strain (e.g., mouse brain-passed versus tissue culture-passed DA strain of the TO subgroup). We raised neutralizing monoclonal antibodies (mAbs) against tissue culture-passed DA and GDVII strains of TMEV. We produced two mAbs against the DA strain which neutralized all members of the TO subgroup, but not the GDVII subgroup strains (GDVII and FA); these two DA mAbs reacted similarly with both mouse brain-passed DA and tissue culture-passed DA. Of six neutralizing GDVII mAbs, four reacted only to GDVII and FA, whereas two neutralized TO strains as well. These mAbs demonstrate the presence of TMEV group-specific as well as subgroup-specific neutralization and substantiate the division of TMEV into two distinct subgroups. On Western immunoblots one of the two DA mAbs reacted against isolated DA VP1, two GDVII mAbs (which were TMEV group specific) reacted against isolated GDVII VP1 and DA VP1, and the other DA mAb and four other GDVII mAbs required an intact virion conformation for reactivity. An analysis of the epitopes recognized by these mAbs may elucidate sites important in TMEV biological activities.  相似文献   

9.
Strain GDVII and other members of the GDVII subgroup of Theiler’s murine encephalomyelitis virus (TMEV) are highly virulent and cause acute polioencephalomyelitis in mice. Neither viral persistence nor demyelination is demonstrated in the few surviving mice. On the other hand, strain DA and other members of the TO subgroup of TMEV are less virulent and establish a persistent infection in the spinal cord, which results in a demyelinating disease. We previously reported that GDVII does not actively replicate in a murine macrophage-like cell line, J774-1, whereas DA strain productively infects these cells (M. Obuchi, Y. Ohara, T. Takegami, T. Murayama, H. Takada, and H. Iizuka, J. Virol. 71:729–733, 1997). In the present study, we used recombinant viruses between these strains of the two subgroups to demonstrate that the DA L coding region of DA strain is important for virus growth in J774-1 cells. Additional experiments with a mutant virus indicate that L* protein, which is synthesized out of frame with the polyprotein from an additional alternative initiation codon in the L coding region of TO subgroup strains, is a key determinant responsible for the cell-type-specific restriction of virus growth. L* protein may play a critical role in the DA-induced restricted demyelinating infection by allowing growth in macrophages, a major site for virus persistence.  相似文献   

10.
The DA strain of Theiler’s virus causes a persistent and demyelinating infection of the white matter of spinal cord, whereas the GDVII strain causes a fatal gray-matter encephalomyelitis. Studies with recombinant viruses showed that this difference in phenotype is controlled mainly by the capsid. However, conflicting results regarding the existence of determinants of persistence in the capsid of the GDVII strain have been published. Here we show that a GDVII virus whose neurovirulence has been attenuated by an insertion in the 5′ noncoding region does not persist in the central nervous systems of mice. Furthermore, this virus infects the gray matter efficiently, but not the white matter. These results confirm the absence of determinants of persistence in the GDVII capsid. They suggest that the DA capsid controls persistence by allowing the virus to infect cells in the white matter of the spinal cord.  相似文献   

11.
The DA strain of Theiler's virus persists in the central nervous systems of mice and causes chronic inflammation and demyelination. The GDVII strain, on the other hand, causes an acute encephalitis that kills the host in a matter of days. We constructed a series of recombinants between two infectious cDNA clones of the genomes of DA and GDVII viruses. Analysis of the phenotypes of the recombinant viruses yielded the following results. (i) Determinants of persistence and demyelination are found only in the VP1 capsid protein of DA virus. (ii) Whereas the VP1 capsid protein of DA virus is able to fully attenuate the neurovirulence of GDVII virus and to allow the chimeric virus to persist and demyelinate, the VP1 capsid protein of GDVII virus is unable to render DA virus neurovirulent. (iii) The mere attenuation of the neurovirulence of GDVII virus does not allow it to persist and demyelinate.  相似文献   

12.
Intratypic recombinant Theiler's viruses prepared between GDVII and DA strains were used to identify genomic sequences important in neurovirulence, virus persistence, and demyelination and to clarify the mechanisms involved in disease induction. The coding region between 1B and 2C of the highly virulent GDVII strain contains a determinant partly responsible for neurovirulence (early paralysis and death) which correlates with elevated levels of infectious virus and the presence of virus antigen within neurons of the brain stem and gray matter of the spinal cord. Both the GDVII and the DA strains of virus contain genetic determinants for late demyelination in spinal cord. However, quantitative analysis of demyelination produced by recombinant GDVII/DA viruses suggest that multiple gene segments influence the number and extent of demyelinating lesions.  相似文献   

13.
Cellular apoptosis induced by viral genes can play a critical role in determining virulence as well as viral persistence. This form of cell death has been of interest with respect to Theiler's murine encephalomyelitis virus (TMEV) because the GDVII strain and members of the GDVII subgroup are highly neurovirulent, while the DA strain and members of the TO subgroup induce a chronic progressive inflammatory demyelination with persistence of the virus in the central nervous system. The TMEV L protein has been identified as important in the pathogenesis of Theiler's virus-induced demyelinating disease (TMEV-IDD). We now show that DA L is apoptotic following transfection of L expression constructs or following DA virus infection of HeLa cells; the apoptotic activity depends on the presence of the serine/threonine domain of L, especially a serine at amino acid 57. In contrast, GDVII L has little apoptotic activity following transfection of L expression constructs in HeLa cells and is antiapoptotic following GDVII infection of HeLa cells. Of note, both DA and GDVII L cleave caspase-3 in BHK-21 cells, although neither implements the full apoptotic machinery in this cell type as manifested by the induction of terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) staining. The differences in apoptotic activities of DA and GDVII L in varied cell types may play an important role in TMEV subgroup-specific disease phenotypes.  相似文献   

14.
L Zhang  A Senkowski  B Shim    R P Roos 《Journal of virology》1993,67(7):4404-4408
Strain GDVII and other members of the GDVII subgroup of Theiler's murine encephalomyelitis virus are highly neurovirulent and rapidly fatal, while strain DA and other members of the TO subgroup produce a chronic, demyelinating disease. GDVII/DA chimeric cDNA studies suggest that a major neurovirulence determinant is within the GDVII 1B through 1D capsid protein coding region, although the additional presence of upstream GDVII sequences, including the 5' untranslated region, contributes to full neurovirulence. Our studies indicate that there are limitations in precisely delineating neurovirulence determinants with chimeric cDNAs between evolutionarily diverged viruses, such as GDVII and DA.  相似文献   

15.
Theiler's murine encephalomyelitis virus (TMEV) is divided into two subgroups based on neurovirulence. During the acute phase, DA virus infects cells in the gray matter of the central nervous system (CNS). Throughout the chronic phase, DA virus infects glial cells in the white matter, causing demyelinating disease. Although GDVII virus also infects neurons in the gray matter, infected mice developed a severe polioencephalomyelitis, and no virus is detected in the white matter or other areas in the CNS in rare survivors. Several sequence differences between the two viruses are located in VP2 puff B and VP1 loop II, which are located near each other, close to the proposed receptor binding site. We constructed a DA virus mutant, DApBL2M, which has the VP1 loop II of GDVII virus and a mutation at position 171 in VP2 puff B. While DApBL2M virus replicated less efficiently than DA virus during the acute phase, DApBL2M-induced acute polioencephalitis was comparable to that in DA virus infection. Interestingly, during the chronic phase, DApBL2M caused prolonged gray matter disease in the brain without white matter involvement in the spinal cord. This is opposite what is observed during wild-type DA virus infection. Our study is the first to demonstrate that conformational differences via interaction of VP2 puff B and VP1 loop II between GDVII and DA viruses can play an important role in making the transition of infection from the gray matter in the brain to the spinal cord white matter during TMEV infection.  相似文献   

16.
17.
Theiler’s murine encephalomyelitis viruses, which are murine picornaviruses, can cause central nervous system inflammatory disease. To study the role of loop II in capsid protein VP1, two mutant viruses of strain DA in which DA loop II amino acids were replaced with strain GDVII amino acids were constructed. Infection of mice with the two mutant viruses led to dramatically different patterns of disease.  相似文献   

18.
GDVII subgroup strains of Theiler's murine encephalomyelitis virus (TMEV) are highly virulent and produce acute polioencephalomyelitis in mice. Neither viral persistence nor demyelination is demonstrated in the few surviving mice. In contrast, DA subgroup strains are less virulent and establish a persistent central nervous system infection which results in demyelinating disease. We previously reported a subgroup-specific infection in a macrophage-like cell line, J774-1 cells; i.e., GDVII strain does not replicate in J774-1 cells, whereas the DA strain actively replicates in these cells. In addition, this subgroup-specific virus growth is shown to be related to the presence of L* protein, a 17 kDa protein translated out-of-frame of the viral polyprotein from an AUG located 13 nucleotides downstream from the polyprotein's AUG. The present paper demonstrated that this subgroup-specific infection is observed in murine monocyte/macrophage lineage cell lines, but not in other murine cell lines including neural cells. An RNase protection assay also suggested that L* protein-related virus growth is regulated at the step of viral RNA replication. As macrophages are reported to be the major cell harboring virus during the chronic demyelinating stage, the activity of L* protein with respect to virus growth in macrophages may be a key factor in clarifying the mechanism(s) of TMEV persistence, which is probably a trigger to spinal cord demyelination.  相似文献   

19.
We sought to confirm the importance of L* protein for growth of Theiler's murine encephalomyelitis virus (TMEV) in a macrophage-like cell line, J774-1. The protein is out of frame with the polyprotein and synthesized in DA but not GDVII subgroup strains of TMEV. A recombinant virus, DANCL*/GD, which substitutes the DA 5' noncoding and L* coding regions for the corresponding regions of GDVII and synthesizes L* protein, grew with little restriction in J774-1 cells. In contrast, another recombinant virus, DANCL*-1/GD, which has an ACG rather than an AUG as the starting codon of L* protein at nucleotide 1079, resulting in no synthesis of L* protein, did not grow well. No significant difference between the rates of adsorption to J774-1 cells of these viruses was observed. RNase protection assay demonstrated that DANCL*/GD viral RNA significantly increased, whereas only a minimal increase was observed for DANCL*-1/GD. The present study suggests that L* protein is required for virus growth in macrophages.  相似文献   

20.
Y Lorch  M Kotler    A Friedmann 《Journal of virology》1983,45(3):1150-1154
GDVII and DA picornaviruses, which represent two biologically distinct subgroups of Theiler's murine encephalomyelitis viruses, were analyzed to detect the presence of a RNA-linked protein, VPg. It was found that the single-stranded RNA genomes isolated from the virions of both viruses contain a protein of approximately 7,000 daltons, which is covalently linked to the 5' end of the RNA. Like in other picornaviruses (e.g., poliovirus and encephalomyocarditis virus), the terminal nucleotide adjacent to the protein was found to be pUp. The possibility that differently charged VPg species exist is also mentioned.  相似文献   

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