Treatment of adult mice with gold sodium thiomalate made the normally non-lethal Semliki Forest virus infection lethal. Associated with this was a significant increase in brain virus titre and a depression of peritoneal macrophage lysosomal enzyme activity. In contrast, treatment of adult mice with the constituent part, thiomalate, did not make the non-lethal Semliki Forest virus infection lethal. Brain virus titre and peritoneal macrophage lysosomal enzyme activity were comparable to the controls. The mechanism by which gold sodium thiomalate increases the virulence of Semliki Forest virus is discussed.

Separation of smooth membrane vesicles from whole mouse brain by isopycnic centrifugation in discontinuous sucrose density gradients show an increased membrane proliferation in gold sodium thiomalate (GSTM) treated mice. Induction of membrane proliferation by GSTM seems to be an important factor in converting the avirulent Semliki Forest virus infection into a lethal one.

Cells within the central nervous system were identified as containing immunoglobulin G, A and M using immunocytochemistry in mice previously infected with Semliki Forest virus, a togavirus causing primary immune-mediated demyelination. Cells positive for these immunoglobulins were counted in cerebellar white matter, parenchyma, meninges and choroid plexus/ventricles. No positively staining cells were seen on day 6 after infection although other inflammatory cells were present at this time and virus-specific immunoglobulin was found in serum. Cells positive for IgG appeared in all areas by day 9 and remained dominant in numbers throughout. IgM-secreting cells appeared in small numbers in the parenchyma first on day 9 and subsequently in other areas, their numbers rising to a maximum on day 12 in all areas and falling thereafter. The number of IgA-secreting cells was small. They appeared by PID 12 and continued to rise on successive sampling days. Initially IgG-positive cells were seen in the perivascular cuffs but by day 12 a few had moved away from the cuffs into the adjacent parenchyma. IgG-positive cells were seen both in and away from cuffs within areas of demyelination. IgM and IgA-positive cells tended to follow the distribution of IgG-positive cells, but in fewer numbers.

Annals of the New York Academy of SciencesVolume 540, Issue 1 p. 672-673 Semliki Forest Virus (A7[74]) Infection of Adult Mice Induces an Immune-Mediated Demyelinating Encephalomyelitis J. K. FAZAKERLEY, J. K. FAZAKERLEY Department of Microbiology, University of Pennsylvania Medical School Philadelphia, Pennsylvania 19104 Department of Microbiology, Neurovirology Unit, St. Thomas ' Hospital London, EnglandSearch for more papers by this authorA. KHALILI-SHIRAZI, A. KHALILI-SHIRAZI Department of Microbiology, Neurovirology Unit, St. Thomas ' Hospital London, EnglandSearch for more papers by this authorH. E. WEBB, H. E. WEBB Department of Microbiology, Neurovirology Unit, St. Thomas ' Hospital London, EnglandSearch for more papers by this author J. K. FAZAKERLEY, J. K. FAZAKERLEY Department of Microbiology, University of Pennsylvania Medical School Philadelphia, Pennsylvania 19104 Department of Microbiology, Neurovirology Unit, St. Thomas ' Hospital London, EnglandSearch for more papers by this authorA. KHALILI-SHIRAZI, A. KHALILI-SHIRAZI Department of Microbiology, Neurovirology Unit, St. Thomas ' Hospital London, EnglandSearch for more papers by this authorH. E. WEBB, H. E. WEBB Department of Microbiology, Neurovirology Unit, St. Thomas ' Hospital London, EnglandSearch for more papers by this author First published: November 1988 https://doi.org/10.1111/j.1749-6632.1988.tb27208.xCitations: 4AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume540, Issue1Advances in NeuroimmunologyNovember 1988Pages 672-673 RelatedInformation

Virus recovery from brain cultures of mice infected with either Semliki Forest and/or Langat depended on the time interval between inoculation of either virus. Mixed infections may alter the course of a disease.

The avirulent demyelinating strain A7(74) of Semliki Forest virus after passage through mouse brain in vivo and mouse brain cell cultures has been shown to react immunologically with immune sera against galactocerebroside, glucocerebroside, total ganglioside and GT1b ganglioside but not against myelin or sulphatide . Semliki Forest virus is known to take host membrane glycolipid into its coat. The importance of the findings is discussed in relation to the production of a possible anti-brain cell auto-immune phenomenon and its implication in a disease such as multiple sclerosis.

Processing tissue for transmission electron microscopy by standard laboratory methods can take two to three days. This makes the development of new techniques time consuming and generally restricts the use of the electron microscope in routine diagnostic work. The possibility of viewing tissue with the electron microscope five hours after sampling using rapid processing techniques is presented. The morphology of the tissue appears undamaged with cell and organelle ultrastructures being readily recognized, as is the presence of virus and its replicating stages. When combined with immunoelectron microscopy a rapid labeling protocol is possible. We have used the technique to develop protein A-gold (6 and 16 nm particles) and ferritin immunoelectron microscopic techniques to demonstrate viral antigens in brain cell cultures and brain tissue from mice infected with Semliki Forest virus.

Adult mice, infected intracerebrally or intraperitoneally with avirulent Semliki Forest virus, do not show mature virus or advanced stages of viral replication in the brain. If myocrisin is given intraperitoneally 3 h before the virus there is enhancement of all stages of viral replication and budding of virus and mature virions are seen. Compared with controls many intracytoplasmic smooth membrane vesicles were seen in the parenchymal cells of the brain treated with myocrisin or with myocrisin and virus. Myocrisin was visible in the brain and has a membrane proliferating effect which may enhance viral synthesis in the early stages of replication, as well as help in the assembly and budding of mature virus. Increased numbers of infiltrating cells were observed in myocrisin treated mice infected with SFV. The formation of mature virus, and its virulence, appears to be related to the degree of membrane proliferation of the brain cells. The inflammation associated with the increased number of infiltrating cells is secondary to this, the whole process promoting the death of the animals rather than survival.

Immunoglobulin G and albumin levels have been measured in the cerebrospinal fluid and serum of Swiss A2G mice following single intraperitoneal inoculation of Semliki Forest virus. This strain of virus used causes a meningoencephalitis followed by immunologically-mediated demyelination. By the use of the levels of immunoglobulin G and albumin in cerebrospinal fluid and serum to calculate the cerebrospinal fluid: serum ratios and the cerebrospinal fluid immunoglobulin G index, it has been shown that the blood-brain barrier breakdown is mild and restricted to within the first 7–8 days after virus inoculation when the inflammatory response is maximal. Immunoglobulin G index provides a measure of synthesis of immunoglobulin G within the blood-brain barrier. Synthesis has been shown to occur from day 10 onwards up to at least day 61 following infection. Arboviruses are known to persist in central nervous system tissue and it is suggested that a continuing immune response within the central nervous system occurs and is perpetuated by persisting virus. Because of the mode of replication of Semliki Forest virus it is also possible that some of the immune response is directed against central nervous system components.

Viruses may be involved in damaging the central nervous system in several different ways in association with neoplasia. Viral meningitis may occur as a result of immunosuppression produced by the disease process itself or by the drugs and irradiation used in therapy. (1, 2) The actual virus involved in a particular case is seldom identified. Animal models such as Marek’s disease (3), a herpes virus infection, in chickens causing lymphomas, polyneuritis and encephalitis have particular interest in relation to what may happen in human reticuloses and their associated neurological complications (4). Certain viruses of the Papova group which heavily infect the oligodendroglia and cause focal demyelination in progressive multi-focal leucoencephalopathy (5) are tumour forming themselves when inoculated into baby hamsters (6). Also, certain human tumours of the CNS have shown some evidence that the cells may have been infected with viruses and that this may have played some part in the tumour formation itself (7). The varied problems posed by the pathogenic potential of viruses in the CNS in relation to malignant diseases will be discussed with particular reference as to how our knowledge might be advanced further in this field.

An ultrastructural study of cerebellar lesions involving axonal and myelin degeneration induced in adult Swiss A2G mice by 3 intraperitoneal inoculations of avirulent Semliki Forest virus is described. Cerebellar white matter samples examined by light and electron miscroscopy 21 days after the first virus infection revealed microcystic areas, degenerating axons, macrophages containing myelin debris as well as normal elements. By light microscopy foci of myelin loss were apparent. At 28 days groups of degenerating axons were apparent in the white matter. No virus was seen in any of the sections.

Adult mice given two or three intraperitoneal inoculations with avirulent Semliki Forest Virus showed typical lesions of a viral encephalitis similar to those caused by a virulent strain of the virus. Demyelination also was seen in the medulla and in the folia of the cerebellar white matter. Neuronophagia was seen only in mice that had had three successive infections. The repeated inoculations of avirulent virus exacerbates the encephalitis of a single inoculation and causes demyelination. The mice did not have neurological clinical signs except for a short-lived weakness of the hind legs. No central nervous system lesions were seen by the 7th and 8th week after the initial infection and all mice recovered.

Antilymphocyte serum given to suppress selectively the cell response to Langat virus in Swiss albino mice prolonged the average survival times. In vitro, lymph-node cells from virus-immunized mice were strongly cytotoxic for syngenic non-neuronal brain cells infected with virus. The implications of these findings are discussed, with particular reference to the concept of autoimmunity.

Virus infections of the central nervous system (C.N.S.) still present a major problem of both diagnosis and management.As each year goes by more and more diseases of the C.N.S. are found to have a viral aetiology.Among the most recent is the subacute sclerosing panencephalitis of measles.' 2 There are many others which are still borderline problems-for example, the progressive multifocal leucoencephalopathy occurring in association with certain types of malignant disease in which particles looking like virions of the papova group of viruses have been seen in large numbers in glial cells.3Kuru, the fascinating progressive neurological disorder of the Fore tribe in New Guinea, has now been transmitted to monkeys, parti- cularly chimpanzees.4The agent responsible for this is of ultra-microscope size and may well be a virus.Many other diseases, such as disseminated sclerosis and motor neurone disease, may be associated with some viral type agent.It is therefore somewhat difficult to generalize about the management of virus C.N.S. disease, but it is clear, however, that one must think in terms of acute viral C.N.S. disease and chronic " slow" or " latent" type virus disease.By far the most important is the acute viral C.N.S. disease. Acute Viral C.N.S. DiseaseThis is seen all over the world as encephalomyelitis.This term is used as for practical purposes encephalitis (inflammation of the brain) or meningitis (inflammation of the meninges) or myelitis (inflammation of the spinal cord) does not exist alone as a clinical entity.The emphasis of the clinical disease may be on any one of these three, but all components are invariably present, and this affects prognosis.For example, what is thought to be a fairly simple case of aseptic meningitis may develop at a later date unpleasant psychological sequelae, such as changes in sleep rhythm, temper tantrums, and changes in personality.Yet at the time of the illness no obvious lesions indicating brain involvement could be detected by ordinary clinical examination.Awareness of this situation will affect management, prognosis, and the handling of relatives.Acute C.N.S. viral disease is that in which clinical C.N.S. involvement occurs within-one month of the primary infection.This is a somewhat arbitrary figure, based on personal experience of different types of encephalomyelitis seen both in Europe and the tropics.It ranges from infections with poliomyelitis, Japanese B virus encephalitis (insect borne), Coxsackie viruses, and those of the specific fevers such as chicken-pox, measles, and mumps.The encephalomyelitic phase occurs as a second phase of the disease after the viraemia has finished.The length of time between this first and second phase varies with different viruses.It may be up to 14 days with members of the tick-borne