Previous Article | Next Article 
Journal of Virology, June 2002, p. 5807-5812, Vol. 76, No. 11
0022-538X/02/$04.00+0 DOI: 10.1128/JVI.76.11.5807-5812.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.
Bone Marrow Chimeras Reveal Non-H-2 Hematopoietic Control of Susceptibility to Theiler's Virus Persistent Infection
Stéphanie Aubagnac, Michel Brahic, and Jean-François Bureau*
Unité des Virus Lents (CNRS URA 1930), Institut Pasteur, 75724 Paris Cedex 15, France
Received 27 November 2001/
Accepted 7 March 2002

ABSTRACT
The DA strain of Theiler's murine encephalomyelitis virus persists
in the white matter of the spinal cords of susceptible mice.
Previous results showed that the difference in susceptibility
to viral persistence between the susceptible SJL/J strain and
the resistant B10.S strain was due to multiple non-
H-2 loci.
The respective roles of hematopoietic and nonhematopoietic cells
in this difference have been evaluated with bone marrow chimeras.
The results show that non-
H-2 loci with a major effect on susceptibility
are expressed in hematopoietic cells. However, the study of
the SJL.B10-
D10Mit180-D10Mit74 congenic line suggests that other
loci expressed in nonhematopoietic cells also play a role.

TEXT
The primary demyelinating disease induced by Theiler's murine
encephalomyelitis virus is studied as an animal model for multiple
sclerosis (
13,
16). After intracranial inoculation, the DA strain
of Theiler's virus replicates in neurons of the brain and spinal
cord in all strains of mice (
30). This encephalomyelitis disappears
after 2 weeks regardless of the mouse genotype. However, in
genetically susceptible mice the virus persists for the lifetime
of the animal in the white matter of the spinal cord in oligodendrocytes,
macrophages, and possibly astrocytes (
3,
15,
18,
25,
26) and
induces chronic inflammation and primary demyelination (
1,
8,
17,
22). A previous study accounted for the variation of viral
RNA level in 17 inbred strains by the interaction of two groups
of loci (
11). One locus with a major effect was named
Tmevp1 for Theiler's murine encephalomyelitis virus persistence locus
1. It is located on chromosome 17 in the
H-2D region. Several
reports strongly suggest that the same locus controls not only
viral persistence but also demyelination (
14,
20,
27,
29) and
that the
H-2Db class I gene plays a major role in resistance
to both (
4,
19,
28). The existence of non-
H-2 susceptibility
loci is shown by the fact that the SJL/J strain is more susceptible
to viral persistence than the B10.S strain, although both bear
the same
H-2s haplotype (
11). Two of these non-
H-2 loci, named
Tmevp2 and
Tmevp3, have been located on chromosome 10 close
to
Ifng by studying an F
1(SJL/J
x B10.S)
x B10.S backcross and
SJL/J lines congenic for different B10.S genetic intervals of
chromosome 10 (
7,
10). However, the
Ifng gene does not explain
the effect of either
Tmevp2 or
Tmevp3 (
7,
24). One of these
studies also showed that other susceptibility loci, with minor
effects, must contribute to the difference in viral RNA load
between these two mouse strains (
10).
The non-H-2 loci responsible for the difference in susceptibility between the SJL/J and the B10.S strains could affect the efficiency of the immune response against the virus or the viral life cycle. To distinguish between these possibilities, we measured the viral RNA load in bone marrow chimeras between these two immunocompatible H-2s strains. The SJL.B10-D10Mit180-D10Mit74 congenic line, which has a small B10.S genetic interval containing the Tmevp3 locus (7), was also studied in an attempt to understand the mechanism of action of this locus.
Five- to 6-week-old mice were irradiated with a 137Cs source at 9.5 Gy for B10.S-H2S/Sg McdJ mice and at either 9.5 or 12 Gy for SJL/J mice (Janvier, Saint-Berthevin, France) and SJL.B10-D10Mit180-D10Mit74 congenic mice (rate of delivery, 1.13 to 1.22 Gy per min). Mice were reconstituted with syngeneic or allogeneic bone marrow cells that had been harvested from the tibias and femurs of age- and sex-matched mice. For the reconstitution, we used 4 x 106 to 6 x 106 bone marrow cells from SJL/J or congenic mice and 1.2 x107 to 1.5 x 107 bone marrow cells from B10.S mice. Reconstituted and 12- to 14-week-old control mice were anesthetized and inoculated intracranially with 104 PFU of the molecularly cloned TMDA1 strain (21, 23) in 40 µl of phosphate-buffered saline. Mice were sacrificed 45 days postinoculation (p.i.). The efficiency of the reconstitution was assessed with peripheral blood lymphocytes at the time of sacrifice for each mouse reconstituted with allogeneic bone marrow cells. The degree of chimerism varied from 72 to 97% regardless of the genotype of the donor and recipient strains (data not shown). Viral RNA load in the spinal cord was quantified by a dot blot assay (11; also see the discussion in reference 1).
Effect of the mouse genotype and bone marrow reconstitution on viral RNA load.
The amount of viral RNA present in the spinal cord at 45 days p.i. was measured for the B10.S, the SJL/J, and the SJL.B10-D10Mit180-D10Mit74 congenic mice and for the same types of mice that had been reconstituted with syngeneic bone marrow cells (Fig. 1; Table 1). The effect of strain origin and reconstitution on viral RNA load was analyzed using a two-way analysis of variance and the Scheffé test. The means of the amount of viral RNA were significantly different among the three strains [F(2; 147) = 19.983; P < 0.0001]. The SJL/J mice were infected at a higher level than the B10.S mice (P = 0.0066). The congenic mice were infected at a higher level than the SJL/J mice (P = 0.0002) and the B10.S mice (P < 0.0001). The mean amount of viral RNA for mice reconstituted with syngeneic bone marrow was similar to that of the nonreconstituted mice [F(1; 147) = 0.006; P = 0.9391]. No interaction between the strain origin and the reconstitution was detected [F(1; 147) = 0.157; P = 0.8551]. Thus, the three strains have different susceptibilities to viral load, and the differences are not affected by the technique used for bone marrow reconstitution.
Immunological status of the chimeras.
The degree of chimerism for reconstituted SJL/J and B10.S mice
was measured at 8 weeks postreconstitution, the time at which
the mice were inoculated, by studying the expression of Ly-9.1
on B220
+, CD3
+, CD4
+, and CD8
+ spleen cells with FACScan (Fig.
2; Table
2). The efficiency of labeling the four cell populations
with the anti-Ly-9.1 monoclonal antibody was always higher than
96.5% for control mice and mice reconstituted with syngeneic
bone marrow. The degree of chimerism was close to 100% for B220
+ splenocytes. The B10.S mice reconstituted with SJL/J bone marrow
showed a high degree of chimerism for CD3
+, CD4
+, and CD8
+ splenocytes
(85 to 90%). A lower degree of chimerism (60 to 70%) was detected
for CD3
+ and CD4
+ splenocytes of SJL/J mice reconstituted with
B10.S bone marrow.
Viral RNA load of chimeras between the two parental strains.
The means of the amount of viral RNA present in the spinal cords
of the chimeras 45 days p.i. were compared according to the
nature of the recipient and the donor strains, using a two-way
analysis of variance and the Scheffé test. As shown in
Fig.
3 and Table
1, the means depended on the donor strain [
F(1;
82) = 8.580;
P = 0.0044] and not on the recipient strain [
F(1;
82) = 0.475;
P = 0.4927]. No interaction between the origin
of the donor and the recipient strain was detected [
F(1; 82)
= 0.345;
P = 0.5588]. These results indicate that the resistance
of the B10.S strain is mediated mainly by hematopoietic cells
and that the lower degree of chimerism for CD3
+ and CD4
+ splenocytes
of SJL/J mice reconstituted with B10.S bone marrow does not
affects their phenotype. Therefore, the non-
H-2 loci with a
major effect on viral RNA load are expressed in the hematopoietic
system, most likely in the immune system. Since the
Tmevp1 locus
has the characteristics of an
H-2 class I gene (
2,
5,
6), all
loci identified so far with a major effect on Theiler's viral
RNA load in the central nervous system of mice seem to act via
the immune system. However, we cannot rule out that the non-
H-2 loci modify permissiveness of monocytes/macrophages to the virus.
It has been noted that susceptibility to demyelination among
mouse strains correlates more with viral genome load than with
infectious titer (
11,
12). Also, Trottier et al. (
31) recently
reported a striking discrepancy during persistent infection
between the viral genome load (10
9 per spinal cord) and infectious
titers (10
2 to 10
4 PFU per spinal cord). They explain this discrepancy
by a restriction in the viral life cycle and/or by the action
of neutralizing antibody. Although our data are consistent with
this (
9,
11), we offer an alternative hypothesis. Accordingly,
the immune system of the resistant strains clears the virus
by killing infected cells before viral assembly, whereas that
of the susceptible strains kills infected cells at the beginning
of virion assembly, allowing low infectivity titers to persist.
At the time of killing, virus RNA replication would be already
well under way, explaining the high viral RNA load observed.
Viral RNA load of chimeras between the parental strains and the SJL.B10-D10Mit180-D10Mit74 congenic line.
The viral RNA load was higher for the congenic line than for
the SJL/J and B10.S strains (Fig.
1). Immunological chimeras
between these three strains were used to test if the high susceptibility
of the congenic line was due to its hematopoietic cells (Fig.
3; Table
1). The mean RNA loads were compared according to the
nature of the recipient and the donor strain using a two-way
analysis of variance and the Scheffé test. These means
depended on both the donor strain [
F(2; 173) = 13.504;
P = 0.0013]
and the recipient strain [
F(2; 173) = 13.741;
P = 0.0012]. Chimeras
with a B10.S donor strain were infected at lower levels than
chimeras with either an SJL/J (
P = 0.0051) or a congenic (
P = 0.0042) donor. When the recipient was the congenic line, the
chimeras were infected at a higher level than when the recipient
was either the SJL/J (
P = 0.0012) or the B10.S (
P = 0.0121)
strain. These results indicate that the susceptibility of the
congenic line is mediated in part by nonhematopoietic cells.
Since the non-
H-2 loci responsible for the difference in viral
RNA load between the two parental strains cannot explain this
result, other susceptibility loci must exist. Different models
were tested to assess the effects of the donor and the recipient
on the phenotypes of the nine chimeras obtained with the three
parental strains. These models assume that (i) non-
H-2 loci
are responsible for the difference of susceptibility of the
SJL/J and the B10.S strains and that (ii) other non-
H-2 loci
explain the phenotype of the congenic line and act independently
of the first loci. The number and position of the second group
of non-
H-2 loci vary according to the model. In one model, one
such locus is located in the B10.S chromosome 10 interval of
the congenic line and the B10.S haplotype is susceptible. In
another model, the same locus exists, but it interacts with
another locus in the SJL background. This interaction occurs
only when the first locus has a B10.S haplotype and the second
one has an SJL/J haplotype. Both models were tested by one-way
analysis of variance against a null model in which the only
loci considered were those that explain the difference between
the SJL/J and B10.S strains. The second model was the only one
which was not rejected in our test when the phenotype was determined
by the genotype of the recipient strain (the
P value was 482
times lower than that of the null model). A biological consequence
of this model is that the two interacting loci are probably
expressed in nonhematopoietic cells. However, we cannot completely
rule out that they are expressed in some immune cells, such
as microglia, which are radiologically resistant and have a
life span longer than the 8 weeks of reconstitution.
In conclusion, non-H-2 loci with a major effect on the susceptibility of the SJL/J and the B10.S strains to Theiler's virus persistence are most probably expressed in the immune system. This result, together with the major effect of H-2 class I genes on persistence, shows that the immune system plays a central role in the control of Theiler's virus RNA load in the central nervous system. Surprisingly, the congenic mouse studied carried a higher viral RNA load than its parents. The study of nine immunological chimeras showed that this could be due to an interaction between two loci. The congenic mouse is presently being studied to clarify the relationship between the interacting locus located in the B10.S chromosome 10 interval and the Tmevp3 locus.

ACKNOWLEDGMENTS
We thank M. Gau for secretarial assistance and A. Freitas, D.
Gonzalez-Dunia, P. Rohrlich, and S. Vigneau for helpful discussion.
This work was supported by grants from the Institut Pasteur Fondation, the Centre National de la Recherche Scientifique, the Association pour la Recherche sur la Sclérose en Plaques, and the National Multiple Sclerosis Society. S.A. is the recipient of a scholarship from the Ministère de l'Education Nationale de l'Enseignement Supérieur et de la Recherche and from the Fondation pour la Recherche Médicale.

FOOTNOTES
* Corresponding author. Mailing address: Unité des Virus Lents (CNRS URA 1930), Institut Pasteur, 28 rue du Dr. Roux, 75724 Paris Cedex 15, France. Phone: (33-1)40613325. Fax: (33-1)40613167. E-mail:
jfb{at}pasteur.fr.


REFERENCES
1
- Aubagnac, S., M. Brahic, and J.-F. Bureau. 1999. Viral load and a locus on chromosome 11 affect the late clinical disease caused by Theiler's virus. J. Virol. 73:7965-7971.[Abstract/Free Full Text]
2
- Aubagnac, S., M. Brahic, and J.-F. Bureau. 2001. Viral load increases in SJL/J mice persistently infected by Theiler's virus after inactivation of the ß2 m gene. J. Virol. 75:7723-7726.[Abstract/Free Full Text]
3
- Aubert, C., M. Chamorro, and M. Brahic. 1987. Identification of Theiler's virus infected cells in the central nervous system of the mouse during demyelinating disease. Microb. Pathog. 3:319-326.[CrossRef][Medline]
4
- Azoulay, A., M. Brahic, and J.-F. Bureau. 1994. FVB mice transgenic for the H-2Db gene become resistant to persistent infection by Theiler's virus. J. Virol. 68:4049-4052.[Abstract/Free Full Text]
5
- Azoulay-Cayla, A., S. Dethlefs, B. Pérarnau, E. L. Larsson-Sciard, F. A. Lemonnier, M. Brahic, and J.-F. Bureau. 2000. H-2Db-/- mice are susceptible to persistent infection by Theiler's virus. J. Virol. 74:5470-5476.[Abstract/Free Full Text]
6
- Azoulay-Cayla, A., S. Syan, M. Brahic, and J. F. Bureau. 2001. Roles of the H-2Db and H-Kb genes in resistance to persistent Theiler's murine encephalomyelitis virus infection of the central nervous system. J. Gen. Virol. 82:1043-1047.[Abstract/Free Full Text]
7
- Bihl, F., M. Brahic, and J.-F. Bureau. 1999. Two loci, Tmevp2 and Tmevp3, located on the telomeric region of chromosome 10, control the persistence of Theiler's virus in the central nervous system. Genetics 152:385-392.[Abstract/Free Full Text]
8
- Brahic, M., and J.-F. Bureau. 1998. Genetics of susceptibility to Theiler's virus infection. Bioessays 20:627-633.[CrossRef][Medline]
9
- Bureau, J.-F., S. Chirinian, S. Ozden, C. Aubert, and M. Brahic. 1990. Isolation of a specific cellular mRNA by subtractive hybridization in Theiler's virus persistent infection. Microb. Pathog. 8:335-341.[CrossRef][Medline]
10
- Bureau, J.-F., X. Montagutelli, F. Bihl, S. Lefebvre, J.-L. Guénet, and M. Brahic. 1993. Mapping loci influencing the persistence of Theiler's virus in the murine central nervous system. Nat. Genet. 5:87-91.[CrossRef][Medline]
11
- Bureau, J.-F., X. Montagutelli, S. Lefebvre, J.-L. Guénet, M. Pla, and M. Brahic. 1992. The interaction of two groups of murine genes determines the persistence of Theiler's virus in the central nervous system. J. Virol. 66:4698-4704.[Abstract/Free Full Text]
12
- Clatch, R. J., H. L. Lipton, and S. D. Miller. 1987. Class II-restricted T cell responses in Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease. II. Survey of host immune responses and central nervous system virus titers in inbred mouse strains. Microb. Pathog. 3:327-337.[CrossRef][Medline]
13
- Clatch, R. J., R. W. Melvold, M. C. Dal Canto, S. D. Miller, and H. L. Lipton. 1987. The Theiler's murine encephalomyelitis virus (TMEV) model for multiple sclerosis shows a strong influence of the murine equivalents of HLA-A, B, and C. J. Neuroimmunol. 15:121-135.[CrossRef][Medline]
14
- Clatch, R. J., R. W. Melvold, S. D. Miller, and H. L. Lipton. 1985. Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease in mice is influenced by the H-2D region: correlation with TMEV-specific delayed-type hypersensitivity. J. Immunol. 135:1408-1413.[Abstract]
15
- Clatch, R. J., S. D. Miller, R. Metzner, M. C. Dal Canto, and H. L. Lipton. 1990. Monocytes/macrophages isolated from the mouse central nervous system contain infectious Theiler's murine encephalomyelitis virus (TMEV). Virology 176:244-254.[CrossRef][Medline]
16
- Dal Canto, M. C., and H. L. Lipton. 1977. Multiple sclerosis. Animal model: Theiler's virus infection in mice. Am. J. Pathol. 88:497-500.[Medline]
17
- Lipton, H. L. 1975. Theiler's virus infection in mice: an unusual biphasic disease process leading to demyelination. Infect. Immun. 11:1147-1155.[Abstract/Free Full Text]
18
- Lipton, H. L., J. Kratochvil, P. Sethi, and M. C. Dal Canto. 1984. Theiler's virus antigen detected in mouse spinal cord 2 1/2 years after infection. Neurology 34:1117-1119.[Abstract/Free Full Text]
19
- Lipton, H. L., R. Melvold, S. D. Miller, and M. C. Dal Canto. 1995. Mutation of a major histocompatibility class I locus, H-2D, leads to an increased virus burden and disease susceptibility in Theiler's virus-induced demyelinating disease. J. Neurovirol. 1:138-144.[Medline]
20
- Lipton, H. L., and R. W. Melvold. 1984. Genetic analysis of susceptibility to Theiler's virus-induced demyelinating disease in mice. J. Immunol. 132:1821-1825.[Abstract]
21
- McAllister, A., F. Tangy, C. Aubert, and M. Brahic. 1989. Molecular cloning of the complete genome of Theiler's virus, strain DA, and production of infectious transcripts. Microb. Pathog. 7:381-388.[CrossRef][Medline]
22
- McAllister, A., F. Tangy, C. Aubert, and M. Brahic. 1990. Genetic mapping of the ability of Theiler's virus to persist and demyelinate. J. Virol. 64:4252-4257. (Author's correction, 67:2427, 1993.)[Abstract/Free Full Text]
23
- Michiels, T., V. Dejong, R. Rodrigus, and C. Shaw-Jackson. 1997. Protein 2A is not required for Theiler's virus replication. J. Virol. 71:9549-9556.[Abstract]
24
- Monteyne, P., F. Bihl, F. Levillayer, M. Brahic, and J.-F. Bureau. 1999. The Th1/Th2 balance does not account for the difference of susceptibility of mouse strains to Theiler's virus persistent infection. J. Immunol. 162:7330-7334.[Abstract/Free Full Text]
25
- Njenga, M. K., K. Asakura, S. F. Hunter, P. Wettstein, L. R. Pease, and M. Rodriguez. 1997. The immune system preferentially clears Theiler's virus from the gray matter of the central nervous system. J. Virol. 71:8592-8601.[Abstract]
26
- Pena Rossi, C., M. Delcroix, I. Huitinga, A. McAllister, N. van Rooijen, E. Claassen, and M. Brahic. 1997. Role of macrophages during Theiler's virus infection. J. Virol. 71:3336-3340.[Abstract]
27
- Rodriguez, M., and C. S. David. 1985. Demyelination induced by Theiler's virus: influence of the H-2 haplotype. J. Immunol. 135:2145-2148.[Abstract]
28
- Rodriguez, M., and C. S. David. 1995. H-2Dd transgene suppresses Theiler's virus-induced demyelination in susceptible strains of mice. J. Neurovirol. 1:111-117.[Medline]
29
- Rodriguez, M., J. L. Leibowitz, and C. S. David. 1986. Susceptibility to Theiler's virus-induced demyelination. Mapping of the gene within the H-2D region. J. Exp. Med. 163:620-631.[Abstract/Free Full Text]
30
- Stroop, W. G., J. R. Baringer, and M. Brahic. 1981. Detection of Theiler's virus RNA in mouse central nervous system by in situ hybridization. Lab. Investig. 45:504-509.[Medline]
31
- Trottier, M., P. Kallio, W. Wang, and H. L. Lipton. 2001. High numbers of viral RNA copies in the central nervous system of mice during persistent infection with Theiler's virus. J. Virol. 75:7420-7428.[Abstract/Free Full Text]
Journal of Virology, June 2002, p. 5807-5812, Vol. 76, No. 11
0022-538X/02/$04.00+0 DOI: 10.1128/JVI.76.11.5807-5812.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.
This article has been cited by other articles:
-
Levillayer, F., Mas, M., Levi-Acobas, F., Brahic, M., Bureau, J. F.
(2007). Interleukin 22 Is a Candidate Gene for Tmevp3, a Locus Controlling Theiler's Virus-Induced Neurological Diseases. Genetics
176: 1835-1844
[Abstract]
[Full Text]
-
Gao, Y., Yang, W., Pan, M., Scully, E., Girardi, M., Augenlicht, L. H., Craft, J., Yin, Z.
(2003). {gamma}{delta} T Cells Provide an Early Source of Interferon {gamma} in Tumor Immunity. JEM
198: 433-442
[Abstract]
[Full Text]
-
Vigneau, S., Rohrlich, P.-S., Brahic, M., Bureau, J.-F.
(2003). Tmevpg1, a Candidate Gene for the Control of Theiler's Virus Persistence, Could Be Implicated in the Regulation of Gamma Interferon. J. Virol.
77: 5632-5638
[Abstract]
[Full Text]