Demyelination in Mice After Two or Three Infections with Avirulent Semliki Forest Virus

Abstract

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.

Changes in Fast Axonal Transport of Glycoproteins in Optic Nerves of Mice Infected With Semliki Forest Virus

“…inoculation of SFV or BAPS. These times correspond, respectively, to at least 4 days before demyelination begins and to the period of demyelination (Chew-Lim et al, 1977). The mice recovered from anaesthesia within 1 h.…”

“…The reduction in transport of glycoproteins cannot have been directly due to the virus itself since replication of SFV within the CNS ceases within a week after SFV inoculation (Illavia et al, 1982;Pathak and Webb, 1988), and is cleared within 12days (Jagelman et al, 1978). It seems more likely that this change was a consequence of demyelination, since myelin loss occurs from PID 14 (Chew-Lim et al, 1977).…”

Virus induced demyelination

“…Foci of inflammation and associated demyelination are apparent throughout the brain, but predominate in the cerebellum . There is little or no destruction of neurons, but astrocytic hypertrophy and gliosis are apparent (Chew-Lim et al, 1977;Mac-Kenzie et al, 1978;Kelly et al, 1982). A detailed electron microscopic study of the development of demyelinating lesions demonstrates early infiltration of lymphocytes, which associate closely with astrocytes, oligodendrocytes, and myelinated axons.…”

Proceedings of the Physiological Society, 4‐5 January 1985, Guy's Hospital Meeting: Poster Communications

“…Inoculation of Semliki Forest Virus (SFV) into mice induces patchy demyelination throughout the CNS (e.g. Chew-Lim, Suckling & Webb, 1977). Daily observations of a large population of control and SFV-infected mice have enabled us to quantify other pathological changes such as weight loss, hind limb paralysis and conjunctivitis both before and during the demyelinating period (which is at a peak from post-infection day (PID) 14 to PID 20).…”