CHARACTERIZATION OF NATURAL EPSTEIN-BARR-VIRUS INFECTION AND REPLICATION IN SMOOTH-MUSCLE CELLS FROM A LEIOMYOSARCOMA

Cells from a leiomyosarcoma tumor (LMS-1) from a patient with the acqu ired immunodeficiency syndrome (AIDS) were explanted, cultured in vitr o, and studied by phase-contrast microscopy for morphologic and growth characteristics, immunostaining for cell markers, EBER in situ hybrid ization and polymerase chain reaction for detection of Epstein-Barr vi rus (EBV), and immunostaining for expression of EBV antigens. The cell s exhibited very slow growth in vitro, with unusual elliptical and spi ndle-shaped morphology and fragmentation of the cytoplasm into long, t apering, cytoplasmic processes. Greater than 90% of cells expressed di ffuse distribution of the smooth muscle isoform of actin by immunopero xidase staining. Approximately 25% of cells expressed very bright fluo rescence by immunostaining of the smooth muscle isoforms of calponin a nd actin. The majority of cells demonstrated a weak signal for CD21; a pproximately 5-10% of cells showed a strong signal that was confined t o cell surfaces. The cultured cells harbored EBV, and infectious EBV c ontinued to be detected by polymerase chain reaction and virus culture through several passages in vitro. Several EBV antigens were expresse d, including latent antigen EBNA-1, immediate-early antigen BZLF1, ear ly antigen EA-D, and late antigens, including viral capsid antigen p16 0, gp125, and membrane antigen gp350. Human umbilical cord lymphocytes that were transformed with virus isolated from cultured cells yielded immortalized cell lines that expressed EBV antigens similar to other EBV-transformed lymphocyte cell lines. These results confirm that EBV is capable of lytic infection of smooth muscle cells with expression o f a repertoire of latent and replicative viral products and production of infectious virus. EBV infection of smooth muscle cells may contrib ute to the oncogenesis of leiomyosarcomas. J. Med. Virol. 57:36-46, 19 99 (C) 1999 Wiley-Liss, Inc.