Virions from progressive multifocal leukoencephalopathy: rapid serological identification by electron microscopy

Virions were extracted directly from the brain of a patient with progressive multifocal leukoencephalopathy (PML). They were treated with antiserum to SV40, with rabbit antiserum to previous PML isolates, or with serum from another patient with the same disease and observed directly by electron microscopy. This procedure could be used for the rapid identification of the antigenic nature of virions in cases of PML.

Further studies of a simian virus 40-like virus isolated from human brain

A virus similar to simian virus 40 was reisolated from brain homogenates of a patient with progressive multifocal leukoencephalopathy onto cultures of human fetal brain cells.

Effects of viral infection on nervous system development. I. Pathogenesis of bluetongue virus infection in mice

Bluetongue vaccine virus was adapted to mice by serial intracerebral passage. The adapted virus was found to multiply selectively in immature cells of the subventricular zone of the forebrain and spread along cell migratory pathways to the olfactory bulbs, caudate/putamen, hippocampus and areas of cerebral cortex. Symmetrical, mineralized, partially cavitated lesions developed in these areas as a sequela of the infection. Infection of fetal mice led to more severe cerebral malformation, and infection of 2-week-old mice resulted in very limited multiplication without sequelae. The pattern of infection correlated with the maturation and migration of cells within the developing telencephalon.

Effects of viral infection on nervous system development. II. Attempts to modify bluetongue-virus-induced malformations with cyclophosphamide and antithymocyte serum

Treatment with cyclophosphamide and antithymocyte serum (ATS) did not significantly increase the susceptibility of mice to bluetongue virus infections of the nervous system. Cyclophosphamide actually inhibited virus growth in newborn and 2-week-old mice and, in newborn mice, diminished the severity of virus-induced pathologic sequelae. Autoradiographic studies suggested this inhibition resulted from the effect of cyclophosphamide on the immature cells of the subventricular zone which were the cell population selectively infected by bluetongue virus. In newborn mice ATS inhibited the inflammatory reaction and development of antibody, but did not result in alterations in mortality, initial virus growth and localization or early necrosis of cells in the subventricular zone. Antithymocyte serum only caused longer persistence of virus and slight extension of late pathologic lesions. The failure of cyclophosphamide and ATS treatment to induce more extensive lesions in older mice show that the age-dependency of bluetongue lesions is not determined by the immaturity of immune responses.

A new influenza A virus infection in turkeys. VII. Comparative immunology

Four influenza A strains isolated from turkeys in Ontario as well as strain Chicken/Scotland/59 were found to immunize turkeys against the lethal disease caused by virus Turkey/Ontario 7732/66 (V7732). These viruses form the avian influenza A serotype 5 (AA5). Immunoprotection against V7732 was not obtained with influenza viruses of other serotypes. Immunoprotective relationships among AA5 viruses were not always demonstrable in hemagglutination-inhibition (HI) and serum-neutralization (SN) tests, especially with turkey and mammalian antisera; better correlation between immunoprotection and these in vitro tests was seen with chicken antisera. The implications of these findings relative to virus classification, serodiagnosis and vaccination are discussed.

A new influenza A virus infection in turkeys. VI. Artificial immunization against the malignant virus strain turkey-Ontario 7732-66

The immune reaction of turkeys and chickens to inactivated preparations of a virulent strain of avian influenza A virus has been examined. In both species any level of antibody detectable by the hemagglutination inhibition or serum neutralization tests was protective against the challenge exposure. However, some vaccinated birds were protected in the absence of detectable antibody. Chickens responded with higher and longer lasting antibody titers than turkeys to identical antigen preparations. Whereas the vaccine induced protection in chickens for at least 84 days, the immune protection in turkeys barely lasted 42 days. Immune birds responded to the live virus challenge with a marked rise in serologic titers which suggest that they were still susceptible to subclinical infection. These findings are discussed in their relationship to available data on classical fowl plague and influenza in mammals.

A new influenza A virus infection in turkeys II. A highly pathogenic variant, a/turkey/ontario 772/66

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A new influenza virus infection in turkeys. I. Isolation and characterization of virus 6213

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