SUMMARYSevere necrotlsmg hepatitis, with microscopic brain lesions containing multi-nucleated giant cells, was observed in specified-pathogen-free nu-nu mice, contained in a semi-protected environment, but within the same room as other, conventional, mice. An entire group of 40 nu-nu mice died within a month, with no evidence of bacterial or parasitic infection. However, cell-free liver filtrates reproduced the liver lesions in specified-pat hogenfree Swiss-Schneider mice injected intraperitoneally at up to 21 days of age, but not in baby rats and hamsters.Electronmicroscopy showed masses of particles resembling mouse hepatitis virus in the liver lesions of the recipient mice, and the identity of the virus was further confirmed serologically and by its physical properties. It was concluded that the infection was caused by a neurotropic variant of mouse hepatitis virus and could have originated from the conventional mice kept in the same room.Nude (nu-nu) mice (Pantelouris, 1968; Artzt, 1972) are immunodeficient as a result of partial or total absence of the thymus at birth. For this reason they are susceptible to infections which do not necessarily affect normal mice, and therefore they have to be derived by hysterectomy and bred within a unit suitable for specified-pathogen-free (SPF) animals or under germ-free conditions. Once issued from such barrier units, nu-nu mice generally have a very short life as they succumb to a variety of conditions or diseases, such as toxoplasmosis, liver lesions (Pantelouris, 1968) or flagellate infestation
Nude (nu/nu) mice bearing human tumour heterografts were affected with posterior paralysis and wasting. There was demyelination and infection of the oligodendrocytes of the spinal cord with a papovavirus. Similar virus particles and inclusion bodies were found in the bronchial epithelium, which showed histopathological changes. Similar changes were shown by the epithelia of the renal pelvis, ureter and choroid plexus. The virus was found in a transplantable human tumour, and evidence of spread by contact was also obtained. Intracerebral injection of spinal cord suspension from infected mice resulted in virus infected cutaneous carcinomata, demyelination with virus particles in the oligodendrocytes and posterior paralysis with wasting in adult nude mice. The suspension injected intraperitoneally into newborn Syrian hamsters produced tumours similar to those produced by murine polyoma. No evidence of infection was found in mice from the colony of origin. The virus was identified as murine polyoma Wild Type A2.
ABSZESSE DER GLANDULAE BULBOURETHRALES VON MAUSEN DURCH PASTEURELLA PNEUMOTROPlCA ABCES DES GLANDES BULBO-URETHRALES DES SOURIS cAusEs PAR PASTEURELLA PNEUMOTROPlCAC3H/Bi/Icrf and Simpson/Jcrf adult male mice are often submitted for investigation, singly or in small groups, with unilateral or bilateral swellings in the perineal region. These invariably prove to be abscesses containing green creamy pus. Bacteriological examination yields Pasteurella pneumatropica in nearly all cases.Careful dissection of the perineal region reveales that the abscesses involve the bulbourethral glands on one or both sides (Fig. 1). Jn some cases an abscess fully replaces the bulbourethral gland on one side, whilst the gland on the other side is enlarged, showing on histological section evidence of infiltration with polymorphs (Fig. 2), accumulation of purulent material in the dilated ducts, and other inflammatory changes.These may be milder or earlier manifestations of the same process that leads to abscess formation. Jn culture the organism produces non-haemolytic, slightly opaque, yellowish coloured colonies of 1 mm diameter on 5 % blood-agar plates after 24 h aerobic incubation. It is a non-motile, small, gram-negative coccobacillus, with a tendency to form short filaments.It is oxidase-, catalase-, urease-and nidole-positive.It produces acid but no gas in glucose, lactose, sucrose, maltose, and xylose, but it does not acidify mannitol and inositol.
SUMMARYNude mice (nu/nu), heterotransplanted with human tumours and kept in isolators, were found to suffer from wasting and posterior paralysis. Electron microscopy of spinal cord tissue revealed virus particles in tlae oligodendrocytes consistent in size (35 to 40 nm), morphology and distribution with those of the polyoma-SV40 sub-group of papovaviruses. Serology and restriction enzyme analysis of the virus genome showed that the virus was the murine polyoma A2 strain. Inoculation of uninfected nude mice with 107 TCID5o of polyoma A2 strain virus produced a similar disease in these mice with wasting and, after 10 to 23 weeks, paralysis of the hind legs of all surviving mice. Extensive myelin disruption was seen throughout the brain stem and sacral region of the spinal cord and high titres of polyoma virus were found in the whole brain (10 s'8 TCID5o/brain) and in the spinal cord (106.8 TCIDs0/spinal cord).
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