George Schidlovsky

Isolation and characterization of a new type D retrovirus from the Asian primate, Presbytis obscurus (spectacled langur)

Abstract A reverse transcriptase-containing virus (retrovirus) was isolated from a cocultivation of langur lung cells with bat and with human cells. This virus, PO-1-Lu, was first detected 6 months after the cocultivation began. Morphologically it resembles Mason-Pfizer monkey virus (MPMV), a type D retrovirus of primates. Study of its antigenic properties and its RNA genome show it to be related to but distinct from MPMV. An interspecies radioimmunoassay using labeled gp70 of baboon type C virus and antiserum to MPMV type D virus detects the PO-1-Lu envelope protein although both the baboon type C- and the MPMV-specific radioimmunoassays for gp70 do not.

Herpesvirus in Marek's Disease Tumors

Intranuclear and cytoplasmic virus particles of the herpes type were located in epithelial cells that line the kidney collecting tubules obtained from a chick with Mareks disease. The chick had contracted the disease by direct contact transmission. The virus was not observed in any of the invading tumor cells in the same kidney.

Detection of Marek's disease herpesvirus antigen by fluorescent and coating antibody.

A strong fluorescence was observed when cell cultures derived from Mareks disease (MD) chick kidney tumors were reacted with sera from MD-infected chickens in indirect immunofluorescence tests. The fluorescence was restricted to the cells that harbored Mareks disease herpesvirus (MDHV). Electron-microscope investigations revealed that immunofluorescent-positive sera readily coated the capsid and the envelope of MDHV particles extracted from cell cultures, indicating that at least part of the antibody evoked in chickens as a result of MD infection is directed against the virus proteins. A great majority (87.4%) of the 215 infected chickens tested, whether they developed gross MD tumors or not, produced antibodies against MDHV particles. Several sera that were strongly positive by indirect immunofluorescence test were found to have dilution endpoints of 1:320 although serum titers did not correlate with the severity of disease. Attempts failed to demonstrate the MDHV antigens in MD tumors directly by immunofluorescence. Upon culture of such tumors, however, the antigen could be detected as early as the third day of cultivation (about two days prior to appearance of recognizable cytopathic effects in the monolayer). Chickens not exposed to MD-infection (housed separately) did not have viral antigen in their kidneys.