EVIDENCE FOR RETROVIRUS INFECTIONS IN GREEN TURTLES CHELONIA-MYDAS FROM THE HAWAIIAN-ISLANDS

Apparently normal Hawaiian green turtles Chelonia mydas and those disp laying fibropapillomas were analyzed for infection by retroviruses. St rikingly, all samples were positive for polymerase enhanced reverse tr anscriptase (PERT) with levels high enough to quantitate by the conven tional reverse transcriptase (RT) assay. However, samples of skin, eve n from asymptomatic turtles, were RT positive, although the levels of enzyme activity in healthy turtles hatched and raised in captivity wer e much lower than those observed in asymptomatic free-ranging turtles. Turtles with fibropapillomas displayed a broad range of reverse trans criptase activity. Skin and eye fibropapillomas and a heart tumor were further analyzed and shown to have reverse transcriptase activity tha t banded in a sucrose gradient at 1.17 g ml(-1). The reverse transcrip tase activity purified from the heart tumor displayed a temperature op timum of 37 degrees C and showed a preference for Mn2+ over Mg2+. Sucr ose gradient fractions of this sample displaying elevated reverse tran scriptase activity contained primarily retroviral-sized particles with prominent envelope spikes, when negatively stained and examined by el ectron microscopy. Sodium dodecylsulfate-polyacrylamide gel electropho resis (SDS-PAGE) analysis of gradient-purified virions revealed a cons erved profile among 4 independent tumors and showed 7 prominent protei ns having molecular weights of 116, 83, 51, 43, 40, 20 and 14 kDa. The data suggest that retroviral infections are widespread in Hawaiian gr een turtles and a comprehensive investigation is warranted to address the possibility that these agents cause green turtle fibropapillomatos is (GTFP).