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Diseases of Aquatic Organisms

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DAO 31:1-7 (1997)  -  doi:10.3354/dao031001

Evidence for retrovirus infections in green turtles Chelonia mydas from the Hawaiian islands

Rufina N. Casey1, Sandra L. Quackenbush1, Thierry M. Work2, George H. Balazs3, Paul R. Bowser1, James W. Casey1,*

1Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA
2U.S. Geological Survey, Biological Resources Division, National Wildlife Health Center, Honolulu Field Station, Honolulu, Hawaii 96850, USA
3National Marine Fisheries Service, Southwest Fisheries Science Center, Honolulu Laboratory, Honolulu, Hawaii 96822-2396, USA
*Addressee for correspondence. E-mail:

Apparently normal Hawaiian green turtles Chelonia mydas and those displaying fibropapillomas were analyzed for infection by retroviruses. Strikingly, all samples were positive for polymerase enhanced reverse transcriptase (PERT) with levels high enough to quantitate by the conventional reverse transcriptase (RT) assay. However, samples of skin, even from asymptomatic turtles, were RT positive, although the levels of enzyme activity in healthy turtles hatched and raised in captivity were much lower than those observed in asymptomatic free-ranging turtles. Turtles with fibropapillomas displayed a broad range of reverse transcriptase activity. Skin and eye fibropapillomas and a heart tumor were further analyzed and shown to have reverse transcriptase activity that banded in a sucrose gradient at 1.17 g ml-1. The reverse transcriptase activity purified from the heart tumordisplayed a temperature optimum of 37°C and showed a preference for Mn2+ over Mg2+. Sucrose gradient fractions of this sample displaying elevated reverse transcriptase activity contained primarily retroviral-sized particles with prominent envelope spikes, when negatively stained and examined by electron microscopy. Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of gradient-purified virions revealed a conserved profile among 4 independent tumors and showed 7 prominent proteins having molecular weights of 116, 83, 51, 43, 40, 20 and 14 kDa. The data suggest that retroviral infections are widespread in Hawaiian green turtles and a comprehensive investigation is warranted to address the possibility that these agents cause green turtle fibropapillomatosis (GTFP).

Green turtle · Reverse transcriptase · Retrovirus · Fibropapillomatosis · Electron microscopy

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