The susceptibility of the hamster to mouse encephalomyelitis virus

The OT strain of mouse encephalomyelitis virus induces an inapparent infection in suckling hamsters associated with lesions of the central nervous system and skeletal muscles. The virus increases in pathogenicity after alternating mouse-hamster transfers and then induces both paralysis and encephalitis. Pathogenicity is lost through serial hamster passages but is restored by a single mouse transfer.

Studies on acute disseminated encephalomyelitis produced experimentally in rhesus monkeys; disseminated encephalomyelitis produced in monkeys with their own brain tissue

Acute disseminated encephalomyelitis has been produced in rhesus monkeys by injection of their own brain tissue, removed surgically and incorporated with adjuvants.

Myositis in mice following intramuscular injection of viruses of the mouse encephalomyelitis group and of certain other neurotropic viruses

A study has been made of the local effects following intramuscular injection of various neurotropic viruses. Early massive necrosis of muscle fibers accompanied by edema and acute inflammatory reaction is produced by Jungeblut's SK virus even in low concentrations. Similar but more slowly developing lesions follow the introduction of mouse encephalomyelitis GD-VII and FA strains. Strain 4727 (TO type) produces inflammatory changes with fibrosis in the intermuscular septa and necrosis of scattered individual fibers. The relatively avirulent FV strain (TO type) was not pathogenic for skeletal muscle. The Mitchell strain of lymphocytic choriomeningitis virus gives rise to a profuse lymphocytic and monocytic infiltration of the fat and connective tissue but does not cause necrosis of muscle fibers. No significant lesions resulted from intramuscular injection of the murine-adapted human poliomyelitis Lansing virus, the HF strain of herpes, a strain of Eastern equine encephalitis virus, or a still unidentified demyelinating mouse virus. Evidence is presented that the mouse encephalomyelitis virus GD-VII and Jungeblut's SK virus multiply locally in the injected limb. The GD-VII virus has been passed through four muscle to muscle passages and muscle lesions have been elicited at the same time. Specific and complete protection against myositis was obtained by anti-GD-VII and anti-SK rabbit sera.

Interleukin 22 is a candidate gene for Tmevp3, a locus controlling Theiler's virus-induced neurological diseases

After intracerebral inoculation, Theiler's virus induces in its natural host, the mouse, an acute encephalomyelitis followed, in susceptible animals, by chronic inflammation and primary demyelination. Susceptibility to demyelination among strains of laboratory mice is explained by the capacity of the immune system to control viral load during persistence. Also, differences of susceptibility to viral load between the susceptible SJL strain and the resistant B10.S strain are mainly due to two loci, Tmevp2 and Tmevp3, located close to the Ifng locus on chromosome 10. In this article, we show that the Tmevp3 locus controls both mortality during the acute encephalomyelitis and viral load during persistence. Most probably, two genes located in the Tmevp3 interval control these two different phenotypes with efficiencies that depend on the age of the mouse at inoculation. Il22, a member of the IL-10 cytokine family, is a candidate gene for the control of mortality during the acute encephalomyelitis.

Acute disseminated encephalomyelitis following immunization with homologous brain extracts; studies on the role of a circulating antibody in the production of the condition in dogs

1. A severe demyelinating condition characterized by ataxia and paralysis, in some instances leading to death, was produced in thirty-five of a total of fifty-five dogs following immunization with homologous brain tissue combined with Freund's adjuvants. In more than 30 per cent of instances paralysis did not occur until immunization was continued for 6 or more months. Only eight dogs became paralyzed after a single injection of antigen. The condition appeared between 6 and 15 days after the last injection in all animals, irrespective of the total number of injections or the duration of immunization. 2. An antibody which reacted in complement fixation tests with aqueous and alcoholic extracts of homologous brain tissue was demonstrable in the majority of immunized dogs, whether or not the animals became paralyzed. It appeared during or after the 3rd week of immunization, and its occurrence or titer could not be correlated with the incidence of the encephalomyelitis. In general, there were fewer dogs with demonstrable antibody in the paralyzed group than in the non-paralyzed group. 3. A flocculation reaction with alcohol extracts of homologous brain was demonstrated in the serum of immunized dogs. The antigen and antibody involved were apparently identical with those responsible for the complement fixation reactions. 4. The brain tissue component which reacted as antigen in the complement fixation test was present in adult brain from several mammalian species, and peripheral nerve. It was not present in the brain of newborn dogs nor in other unrelated organs. It was demonstrable in brain tissue which had been allowed to autolyze, or treated with 10 per cent formalin. It was not impaired by boiling, or by acid hydrolysis, and was contained in the unsaponifiable fraction of brain lipids. It was separable from cholesterol by digitonin precipitation of the latter. 5. Immunization of dogs with the unsaponifiable fraction of homologous brain, in adjuvants, caused the appearance of antibrain antibody similar to that in animals injected with whole brain. Encephalomyelitis was not observed during a 2 month period of immunization with this fraction. 6. In guinea pigs, an injection of the unsaponifiable fraction of brain, in adjuvants, was followed by fatal meningoencephalitis, but the identity of the state with that caused by whole brain antigens was not established.

Studies on acute disseminated encephalomyelitis produced experimentally in Rhesus monkeys; complement-fixing antibodies

1. Animals injected with emulsions of monkey brain with adjuvants show a complex pattern of antibody response as determined by complement fixation tests. 2. Organ-specific complement-fixing antibodies to constituents of brain tissue may be formed which fix complement with brain tissues of various animal species but fail to react with other organs or with rabbit placenta. 3. Antibodies may be formed to some constituent of brain other than nervous tissue. It would seem that these can be detected by the strong complement fixation given with rabbit placenta. 4. Sera from individual animals may contain antibodies to the brain or placenta constituents, to both, or to neither. Occasional individual sera show unique patterns of antibody response as determined with various additional antigens such as fetal brain, posterior pituitary, or peripheral nerves. 5. No evidence of any etiological relationship between the development of encephalomyelitis and the complement-fixing antibodies to brain demonstrable in the sera could be found. The complement-fixing antibody to the placental constituent was unrelated to the encephalomyelitis.