Identification of a small, naked virus in tumor-like aggregates in cell lines derived from a green turtle, Chelonia mydas, with fibropapillomas

Serial cultivation of cell lines derived from lung, testis, periorbital and tumor tissues of a green turtle (Chelonia mydas) with fibropapillomas resu lted in the in vitro formation of tumor-like cell aggregates, ranging in si ze from 0.5 to 2.0 mm in diameter. Successful induction of tumor-like aggre gates was achieved in a cell line derived from lung tissue of healthy green turtles, following inoculation with cell-free media from these tumor-beari ng cell lines, suggesting the presence of a transmissible agent. Thin-secti on electron microscopy of the cell aggregates revealed massive collagen dep osits and intranuclear naked viral particles, measuring 50 +/- 5 MI in diam eter. These findings, together with the morphological similarity between th ese tumor-like cell aggregates and the naturally occurring tumor, suggest a possible association between this novel virus and the disease. Further cha racterization of this small naked virus will clarify its role in etiology o f green turtle fibropapilloma. a life-threatening disease of this endangere d marine species. (C) 2000 Published by Elsevier Science B.V. All rights re served.