Theiler's Mouse Research Articles

Genes for tRNA recycling are upregulated in response to infection with Theiler's mouse encephalitis virus

The concept of tRNA recycling has recently emerged from the studies of ribosome-associated quality control. Therein tRNase ZS removes the 2′, 3′>p from the ANKZF1-cleaved tRNA and the subsequent TRNT1 action re-generates the intact tRNA. To know the roles of the tRNA recycling in vivo, we investigated how viral infection affects the tRNA recycling system by analyzing the mRNA levels of tRNase ZS and TRNT1. We found that both genes in HeLa cells are upregulated in response to infection of Theiler's mouse encephalitis virus but not to that of an influenza A virus. Upregulation was also observed in cells infected with encephalomyocarditis virus with reduced efficiency. The levels of the IFN-β mRNA appeared to positively correlate with those of the tRNase ZS and TRNT1 mRNAs. The tRNase ZS gene may be regulated post-transcriptionally in the cells infected with Theiler's mouse encephalitis virus.

Transcription from the proximal promoter of ELAC1, a gene for tRNA repair, is upregulated by interferons

tRNase ZS (ELAC1) and TRNT1 function in tRNA recycling. Recently, we have shown that these genes are upregulated in the cells infected with Theiler's mouse encephalitis virus (TMEV), implying that tRNA recycling functions in response to viral infection. To address the molecular mechanism underlying the ELAC1 upregulation in the cells infected with TMEV, we performed luciferase assays using various plasmid constructs harboring the ELAC1 promoter region. The luciferase expression from a construct containing the full-length ELAC1 promoter was augmented by TMEV, poly IC, IFN-β, or IFN-γ. We identified four IFN-stimulated responsible elements (ISREs) in the proximal promoter region. The luciferase expression from the constructs that lack all the ISREs was strongly reduced compared with that from the constructs with the four ISREs in the presence of IFN-β or IFN-γ. The observation that the ISREs from the ELAC1 promoter are essential for the gene upregulation by IFN-β or IFN-γ suggests that the ELAC1 gene is upregulated by IFNs.

A survey of rodent-borne pathogens carried by wild-caught Norway rats: A potential threat to laboratory rodent colonies

Unintentional infection of laboratory rodents can compromise scientific research as well as the health of the animals and animal handlers. The source of contamination often is unknown, but may be introduced by wild rats from surrounding environments. To determine whether rats in Baltimore, Maryland, USA carry infectious agents commonly found in laboratory rodent colonies, we live-trapped 162 rats during 2005 to 2006 and screened them for a panel of viruses, bacteria and parasites. Antibodies against rat coronavirus/sialodacryoadenitis virus (91.7%), Mycoplasma pulmonis (72.9%), cilia-associated respiratory bacillus (52.1%), rat parvovirus/rat minute virus (29.2%), Kilham rat virus (10.4%), Toolan's H-1 virus (10.4%), Sendai virus (4.2%) and Theiler's mouse encephalomyelitis virus (4.2%), were detected in wild-caught Norway rats. Antibodies against reovirus and pneumonia virus of mice were not detected in wild Norway rats. Endoparasites, including Nippostrongylus braziliensis (71.6%), Rodentolepis nana or Hymenolepis diminuta (34.4%), Hetarakis spumosa (24.1%) and Trichuris muris (14.8%), as well as ectoparasites (14.8%), were identified in wild-caught rats. The risk of pathogen transmission from wild-caught rats to laboratory colonies needs to be mitigated by minimizing exposures rather than assuming wild animals represent a minimal hazard.

Simultaneous Serodetection of 10 Highly Prevalent Mouse Infectious Pathogens in a Single Reaction by Multiplex Analysis

Under current practices of mouse colony maintenance, sera from mice are analyzed for antibodies against several widespread infectious pathogens by conventional immunoassays, generally enzyme-linked immunosorbent assay (ELISA). To test for multiple agents, these methods consume large volumes of mouse serum and are laborious and time-consuming. More efficient immunoassays, using small amounts of sample, are therefore needed. Accordingly, we have developed a novel multiplex diagnostic system that employs fluorescent microbeads, coated with purified antigens, for simultaneous serodetection of 10 mouse infectious agents. Individually identifiable, fluorescent microbeads were coated with antigens from Sendai virus, mouse hepatitis virus, Theiler's mouse encephalomyelitis virus/GDVII strain, mouse minute virus, mouse cytomegalovirus, respiratory enteric orphan virus (Reo-3 virus), mouse parvovirus, calf rotavirus for epizootic diarrhea virus of infant mice, vaccinia virus for ectromelia virus, and Mycoplasma pulmonis. Standard sera, singly positive for antibodies to individual infectious agents, were generated by inoculation of BALB/cj and C57BL/6j mice. Sera from these experimentally infected mice, as well as sera from naturally infected mice, were analyzed using a mixture of microbeads coated with antigens of the 10 infectious agents listed above. Results demonstrated that the multiplex assay was at least as sensitive and specific as ELISA for serodetection. Importantly, the multiplex assay required only 1 microliter of serum for simultaneous serodetection of the 10 mouse infectious agents in one reaction vessel. Thus, this multiplex microbead assay is a reliable, efficient, and cost-effective diagnostic modality that will impact serosurveillance of mice used in research.

Murine viruses in an island population of introduced house mice and endemic short-tailed mice in Western Australia.

House mice (Mus domesticus) were recently introduced to Thevenard Island, off the northwest coast of Western Australia. This island is also habitat for an endangered native rodent, the short-tailed mouse (Leggadina lakedownensis). Concerns have been raised that house mice may pose a threat to L. lakedownensis both through competition and as a source of infection. To assess the threat to L. lakedownensis posed by viral pathogens from M. domesticus, a serological survey was conducted from 1994 to 1996 of both species for evidence of infection with 14 common murine viruses (mouse hepatitis virus, murine cytomegalovirus, lymphocytic choriomeningitis virus, ectromelia virus, mouse adenovirus strains FL and K87, minute virus of mice, mouse parvovirus, reovirus type 3, Sendai virus, Theiler's mouse encephalomyelitis virus, polyoma virus, pneumonia virus of mice, and encephalomyocarditis virus) and Mycoplasma pulmonis. Despite previous evidence that populations of free-living M. domesticus from various locations on the Australian mainland were infected with up to eight viruses, M. domesticus on Thevenard Island were seropositive only to murine cytomegalovirus (MCMV). Antibodies to MCMV were detected in this species at all times of sampling, although seroprevalence varied. Infectious MCMV could be isolated in culture of salivary gland homogenates from seropositive mice. In contrast, L. lakedownensis on Thevenard Island showed no serological evidence of infection with MCMV, any of the other murine viruses, or M. Pulmonis, and no virus could be isolated in culture from salivary gland homogenates. Although MCMV replicated to high titers in experimentally infected inbred BALB/c laboratory mice as expected, it did not replicate in the target organs of experimentally inoculated L. lakedownensis, indicating that the strict host specificity of MCMV may prevent its infection of L. lakedownensis. These results suggest that native mice on Thevenard Island are not at risk of MCMV infection from introduced house mice, and raise interesting questions about the possible selective survival of MCMV in small isolated populations of M. domesticus.

Transmission of murine viruses and mycoplasma in laboratory mouse colonies with respect to housing conditions.

Pathogen-free sentinel mice were placed in 7 animal rooms with different housing conditions and were serologically screened for antibodies to mouse hepatitis virus (MHV), pneumonia virus of mice (PVM), Sendai virus, reovirus 3, Theiler's mouse encephalomyelitis virus (TMEV), ectromelia virus and Mycoplasma pulmonis by enzyme-linked immunosorbent assays, at intervals after introduction. The most commonly detected antibody was against MHV, which was found in mice from 4 rooms, followed by PVM antibody in mice from 3 rooms. Seroconversion to Sendai virus and TMEV was detected in mice from one room each. No seroconversion to any of the antigens was found in 2 rooms. The common criteria of these 2 rooms were that they housed pathogen-free animals from a single source and that the access to the rooms was, purposely or not, restricted to people who had no contact to other mice. The study demonstrated the importance of husbandry and hygienic regimen on the prevalence of infectious agents in laboratory mice.

Theiler's virus encephalomyelitis is unaffected by treatment with myelin components

Treatment of SJL/J mice with myelin components prior to infection with Theiler's picornavirus did not effect the development of inflammatory demyelinating lesions characteristic of Theiler's mouse encephalomyelitis. These results suggest that the pathogenesis of this disease differs from experimental autoimmune encephalomyelitis, which can be suppressed by such a treatment.

The TO strains of Theiler's viruses cause “slow virus—like” infections in mice

Intracerebral inoculation of mice with tissue culture–adapted TO strains of Theiler's mouse encephalomyelitis viruses results in a clinical disease consisting of spastic paralysis due to demyelination after a lengthy incubation period. Thus, in effect, these ordinary picornaviruses are capable of causing a slow infection in their natural host, the mouse. In addition, through the use of tissue culture–adapted virus stocks, virus content in mouse tissues now can be accurately quantified by standard plaque assay.

Dagen des Oordeels

To stimulate creative thinking about, and further modeling of, pathokinetic mechanisms, two devices are used herein: personification, from the point of view of the muscle fiber, and juxtaposition of known or probable mechanisms with proposed possible mechanisms. Brutal terms dramatize the death of muscle fibers. "Assassinations" are imposed on the muscle fiber through mechanisms exogenous to the fiber; "suicides" are brought on by endogenous defects of the muscle fiber. <h3>MECHANISMS AND EXAMPLES (CATEGORIZATION ARBITRARY)</h3><h3>Assassination</h3> <b>Assassination, Direct, Simple.</b>—<i>Exogenous poisons, viruses, and protozoa</i>of various sorts can affect muscle cells. They vary regarding specificity for skeletal muscle cells vs other cells. Poisons include bupivacaine,¹iodoacetate,²20,25-diazacholesterol,^3-62,4-dichlorophenoxyacetic acid,^4,7-11chlofibrate,¹²perhexiline maleate,¹³vincristine,¹⁴and dinitrophenol.^15-16Myotrophic viruses include coxsackie virus, Theiler's mouse encephalomyelitis and Jungblut's SK virus,¹⁷avian leukosis sarcoma virus (for avian muscle),^15,18and mouse C-particle-producing RNA tumor virus

Characterization of the TO strains of Theiler's mouse encephalomyelitis viruses

Theiler's mouse encephalomyelitis virus isolates from the central nervous systems of spontaneously paralyzed mice and stools of asymptomatic mice resemble Theiler's original virus isolates. In this study four such strains were adapted by blind subpassage to replicate and to produce cytopathic effect in cell culture. These viruses were then found to be closely related to each other and to GDVII virus by cross-neutralization and to form small plaques. Bovine serum was found to contain cross-reacting antibodies to these viruses.

Central Nervous System Immunity in Mice Infected with Theiler's Virus. I. Local Neutralizing Antibody Response

Experimental Theiler's mouse encephalomyelitis virus (TMEV) infection in mice is atypical of most other picornavirus infections because virus persists in the host. It was shown previously that low levels of infectious virus are readily detectable in the central nervous system (CNS) despite the presence of substantial titers of serum neutralizing antibody. In this study antibody assays were performed on CNS tissue homogenates, and neutralizing antibody was regularly found in the CNS of TMEV-infected mice. That neutralization by infected CNS extracts was due to antibody was demonstrated by the specificity of neutralization for TMEV and by elimination or marked reduction of neutralization by in vitro treatment with goat antiserum to mouse IgG. In addition, immunofluorescent staining consistently revealed IgG- but not IgM-containing cells in perivascular cuffs and parenchymal lesions of the brains of infected animals. Evidence of local antibody formation in the CNS was found in the actual reversal of the serum-CNS antibody ratio in about one-third of infected mice after three weeks. In contrast, normal mice had a mean serum-CNS antibody ratio of approximately 100:1 after passive transfer of antibody. Possible reasons for the fact that TMEV is not neutralized by antibody and chronic infection is not aborted include the formation of complexes of infectious virus and antibody in the CNS and the production of antibodies with low affinity for TMEV.

Contrasting effects of immunosuppression on Theiler's virus infection in mice

In the present study, cyclophosphamide and rabbit anti-mouse thymocyte serum were used to immunosuppress SJL/J mice infected with Theiler's mouse encephalomyelitis virus (TMEV) in order to delineate the potential mechanism(s) of virus-induced cellular injury in this infection. Whereas both immunosuppressive agents produced a significant increase in mortality, this treatment had differing effects on the pathological involvement of gray and white-matter structures in the central nervous system. The central nervous system of immunosuppressed TMEV-infected mice had increased microglial cell proliferation and neuronal necrosis, longer maintenance of high virus levels and spread of virus antigen to involve the neocortex and hippocampal complex. These observations indicate that TMEV causes a cytolotic infection of neurons and possibly other cells in gray matter. In contrast, immunosuppression produced a dramatic reduction in mononuclear inflammatory cells in the leptomeninges and spinal cord white matter of infected mice and prevented demyelination. Further, virus antigen was not detected in the leptomeninges and white matter of immunosuppressed and infected mice. These findings suggest that demyelination of TMEV infection is immune mediated.

Virus Studies With Germfree Mice. II. Comparative Responses of Germfree Mice to Virus Infection2

Despite the consequences of a microorganism-free existence, germfree mice responded to infection with certain viruses in a manner comparable to that of conventionally reared mice. Serologic responses of germfree and conventional mice to polyoma and pneumonia virus of mice, measured by hemagglutination-inhibition, and to reovirus type 3, measured by complement fixation as well, were comparable both in time course and final antibody titer. Further, the susceptibility of germfree mice to infection with influenza, pneumonia virus of mice, epizootic diarrhea of infant mice, and possibly Theiler's mouse encephalomyelitis viruses was not different from that of conventional mice. No differences in the quantity or rate of influenza virus replication were detected between the groups.

Cultivation of egg-adapted Theiler's mouse encephalomyelitis (TO) virus in chick tissue culture.

Summary1. An egg-adapted strain of Theiler's mouse encephalomyelitis virus (TO) has been carried through 42 passages in vitro on embryonic chick tissue. Attempts to adapt the mouse passage virus directly to chick tissue culture were unsuccessful. Preliminary growth in embryonated eggs, followed by tests in mice of 20% embryo suspensions, facilitated the titration of tissue culture fluids. 2. One of 3 strains of approximately the same mouse-infective titer failed to adapt either to egg or tissue culture. 3. A representative strain of Theiler's mouse encephalomyelitis (TO) virus obtained from the American Type Culture Collection also adapted to egg and tissue cultivation.

Zika Virus (I). Isolations and serological specificity

1. (1) The isolation of what is believed to be a hitherto unrecorded virus is described. The first isolation was made in April 1947 from the serum of a pyrexial rhesus monkey caged in the canopy of Zika Forest. The second isolation was made from a lot of A. africanus taken in January, 1948, in the same forest. The virus has been called Zika virus after the locality from where the isolations were made. 2. (2) Cross neutralization tests indicate that Zika virus is not related to yellow fever, Hawaii dengue nor to the FA and GD VII strains of Theiler's mouse encephalomyelitis virus. Neutralization tests with Zika virus and the antisera of some other viruses which are neurotropic in mice gave no evidence of any identity of these with Zika virus.

Factors Affecting the Propagation of Theiler's Gdvii Mouse Encephalomyelitis Virus in Tissue Cultures

Summary The GDVII strain of Theiler's mouse encephalomyelitis has been carried through 50 serial passages in flasks of Simms' solution with minced brains of embryonic or one day mice; brains from mice as old as 9 days may be used. Temperature range for growth is 31–37 C; optimal pH is 7–9, the higher pH favors more rapid virus production. Culture flasks of medium and tissue stored for as long as 2 days at 5 C or 35 C before virus was added still yielded as much virus after incubation as if fresh tissue was used. Glucose increased yield of virus at pH 7 but not at pH 9. The following substances did not affect yield of virus in culture: CO, NH4Cl, NaF, Al, Cr, Sr, d-ribose, lactate, succinate, pyruvate, thiamine, riboflavin, nucleic acid, choline, alanine, phenylalanine, glutamic acid, thyroxin, sulfadiazine, para-aminobenzoic acid. The following substances decreased yield of virus, Mn, Zn, Fe, Cu, Co, Ni, NaCN, NaN3, iodoacetate and 2,4-dinitrophenol. Virus was also carried through 26 passages in tissue cultures of chick embryo brain but not other chick embryo tissues. Virus was passed 20 times in embryonated eggs of 8–16 days by intracerebral injection. Embryos usually survived without gross or histologic signs of infection.

Detection of the Virus of Mouse Encephalomyelitis in the Intestines of Normal Kangaroo Rats

Summary An infectious agent capable of producing encephalomyelitis in mice has been detected in the intestines of normal kangaroo rats. These rats had been quartered for over a year in a laboratory which had also been inhabited by normal and poliomyelitis-infected monkeys and by albino mice proven to be intestinal carriers of Theiler's mouse encephalomyelitis virus. By means of cross immunity tests and complement fixation reactions this virus has been shown to be immunologically related to the FA strain of mouse encephalomyelitis virus.

Concentration of Dilute Solutions of Virus of Mouse Encephalo-myelitis by Pervaporation and Ultracentrifugation.

SummaryMouse brains infected with the FA strain of Theiler's mouse encephalomyelitis virus have been diluted ten million times so that the solutions were no longer infective. By means of pervaporation it has been possible to concentrate 4000 cc samples of such inactive solutions into volumes of 40 to 80 cc. The virus present in the pervaporated solutions has been further concentrated by sedimentation in the ultracentrifuge into active fractions less than 1 cc in volume.