Abstract

Astroviruses are non-enveloped RNA viruses causing diarrhea in birds and mammals. Four bottlenose dolphin astroviruses (TtAstV-1, TtAstV-2, TtAstV-3, and TtAstV-6) were assessed among multiple populations using quantitative PCR on feces, and TtAstV-1 was also assessed using serology. Among a managed Tursiops collection living in open bay enclosures, the percentages of dolphins with detectable astrovirus in feces for TtAstV-1, TtAstV-2, TtAstV-3, and TtAstV-6 were 22/32 (69%), 3/29 (10%), 1/32 (3%), and 4/32 (13%), respectively. The median TtAstV-1 copies detected was 30 (range 2–5,180). Samples from 2007 had significantly higher TtAstV1 copy numbers than those from 2008 (P < 0.0001). When comparing fecal TtAstV loads by clinical vs. routine sample, appetite, or behavior, only behavior had a significant association; dolphins with abnormal behavior had higher TtAstV-1 loads (32 versus 81 copies, P = 0.05). TtAstV1 was found in 6 of 13 (46%) stranded cetaceans from New England, including a Tursiops, two Balaenoptera acutorostrata, two Kogia breviceps, and a Delphinus delphis. The ELISA serosurvey for TtAstV1 antibodies included 40 managed collection Tursiops from a closed water system; 58 managed open water collection Tursiops; 60 wild Tursiops resident to a bay in west central Florida and 7 stranded Tursiops. No differences were identified (defined by P > 0.05) between wild animals (median value 1.27) and open-water mature animals (median value 1.05). The values from calves (median value 0.38) were lower than open-water mature animals (P < 0.01), wild animals (P < 0.001), and closed system animals (median value 0.94, P < 0.05). The values from closed system animals were lower than wild dolphins (P < 0.05). Of wild animals examined, the two animals with values less than 0.5 were calves. Similar to humans, antibodies among four calves (0–382 days old) increased significantly with age (R² = 0.49– 0.99). TtAStV1 appears to be prevalent in both wild and collection dolphin populations and may have clinical relevance, especially in calves.

Acknowledgements

This work was funded by research grants No. N00014-06-1-0250 and N00014-09-1-0252 from the Office of Naval Research to Hendrik Nollens and research contract No. N66001-08-D-0070 from the Department of Defense to PKY. We would like to thank the staff of the U.S. Navy Marine Mammal Program for their help with sample collection; Linda Archer, Jennifer Burchell and Celeste Benham for their assistance in the laboratory, and Charles Innis from New England Aquarium for supplying fecal samples from stranded cetaceans. Samples from wild Tursiops were collected from Sarasota Bay, Florida, with the support of Dolphin Quest, Disney Worldwide Conservation Fund, Georgia Aquarium, and NOAA Fisheries Service, under NMFS Scientific Research Permit No. 522-1785.