The cytomorphology and cytogenesis of BK virus-transformed hamster brain cells (HBBK cells) were studied. HBBK cells with indistinct processes showed a tendency to epithelial arrangement as well as characteristics of malignant tumor cells in vitro, and developed long, delicate processes when cell growth was suppressed. Glial fibrillary acidic protein was demonstrated by immunofluorescence in the cytoplasm of almost all HBBK cells. The tumors arising in hamsters after subcutaneous inoculation of HBBK cells were classified as poorly differentiated gliomas. These findings suggest that selective transformation of glial cells in hamster brain cells by BK virus occurred.

Animals↗

PubMed1978

Redistribution of intramembrane particles of human erythrocytes induced by HVJ (Sendai virus): a prerequisite for the virus-induced cell fusion.

Aggregation of intramembrane particles of human erythrocytes was found to be induced by HVJ (Sendai virus) under conditions which lead to cell fusion. Degree of polyerythrocyte formation was compared under a variety of conditions with extent of cluster formation observed with the same preparations. Both structural changes of the membranes, ie, fusion and clustering of the particles, behaved very similarly under widely different virus-to-cell ratios and over the time course of cell fusion. Furthermore, by inclusion of high concentrations of antispectrin antibodies within the ghosts, inhibition of clustering of intramembrane particles and hindrance of virus-induced cell fusion were found to occur simultaneously. Antibodies by themselves did not induce aggregation of particles under isotonic conditions, whereas particle clustering could be induced under hypotonic conditions at antibody concentrations causing partial cross-linking of spectrin molecules. In conclusion, clustering of intramembrane particles seems to be required for virus-induced fusion of human erythrocytes.

Antigen-Antibody Reactions↗

PubMed1978

Participation of spectrin in Sendai virus-induced fusion of human erythrocyte ghosts.

Fusion of washed human erythrocyte ghosts could be induced by the addition of Sendai virus after they were loaded with bovine serum albumin and resealed. Antispectrin antibody purified on a spectrin-Sepharose column and sequestered in the ghosts at 4-5 mg/ml together with the albumin was highly inhibitory for the virus-induced cell fusion, whereas Fab fragments prepared from the same antibody were without effect. The virus-induced aggregation of intramembrane particles of human erythrocytes was also inhibited by the same concentrations of the antispectrin antibody. The virus-induced agglutinations of the ghosts and release of bovine serum albumin from the ghosts (which might be caused by fusion of the viral envelope to the erythrocyte membrane) were not inhibited by the sequestered antibody. Therefore, the antibody seems to inhibit fusion at the last step--i.e., fusion between adjacent erythrocyte membranes. Similarities and differences of the mode of participation of spectrin in the virus-induced fusion and in other membrane-linked phenomena of human erythrocytes are discussed.

Antigen-Antibody Reactions↗

PubMed1978