Association of herpesvirus with fibropapillomatosis of the green turtle Chelonia mydas and the loggerhead turtle Caretta caretta in Florida

Sea turtle fibropapillomatosis (FP) is a disease marked by proliferation of benign but debilitating cutaneous fibropapillomas and occasional Visceral fibromas. Transmission experiments have implicated a chloroform-sensitive t ransforming agent present in filtered cell-free tumor homogenates in the et iology of FP. In this study, consensus primer PCR methodology was used to t est the association of a chelonian herpesvirus with fibropapillomatosis. Fi bropapilloma and skin samples were obtained from 17 green and 2 loggerhead turtles affected with FP stranded along the Florida coastline. Ninety-three cutaneous and visceral tumors from the 19 turtles, and 33 skin samples fro m 16 of the turtles, were tested. All turtles affected with FP had herpesvi rus associated with their tumors as detected by PCR. Ninety-six percent (89 /93) of the tumors, but only 9% (3/33) of the skin samples, from affected t urtles contained detectable herpesvirus. The skin samples that contained he rpesvirus were all within 2 cm of a fibropapilloma. Also, 1 of 11 scar tiss ue samples from sites where fibropapillomas had been removed 2 to 51 wk ear lier from 5 green turtles contained detectable herpesvirus. None of 18 nor mal skin samples from 2 green and 2 loggerhead turtles stranded without FP contained herpesvirus. The data indicated that herpesvirus was delectable o nly within or close to tumors. To determine if the same Virus infected both turtle species, partial nucleotide sequences of the herpesvirus DNA polyme rase gene were determined from 6 loggerhead and 2 green turtle samples. The sequences predicted that herpesvirus of loggerhead turtles differed from t hose of green turtles by only 1 of 60 amino acids in the sequence examined, indicating that a chelonian herpesvirus exhibiting minor intratypic variat ion was the only herpesvirus present in tumors of both green and loggerhead turtles. The FP-associated herpesvirus resisted cultivation on chelonian c ell lines which support the replication of other chelonian herpesviruses. T hese results lead to the conclusion that a chelonian herpesvirus is regular ly associated with fibropapillomatosis and is not merely an incidental find ing in affected turtles.