Astroviruses are enteric RNA viruses belonging to the family Astroviridae. Electron microscopic analysis of routine fecal samples from one bottlenose dolphin (Tursiops truncatus), two captive managed and one free-ranging California sea lions (Zalophus californianus), and one Steller sea lion (Eumetopias jubatus) showed particles consistent with Astroviruses. Degenerate primers were designed targeting conserved regions of astroviral genomes. Phylogenetic analysis of the resulting sequences revealed five distinct astrovirus species, significantly expanding known astroviral diversity.
A serosurvey of managed-collection and free-ranging dolphins using a peptide-based ELISA demonstrated that dolphins greater than 25 years old had higher antibody levels compared to dolphins younger than 5, and samples collected during April through June had higher antibody levels compared to the other three quarters (P = 0.01). Dolphin astrovirus (TtastV-1) appears to be a common virus that follows epidemiology similar to astroviruses in other species. Serologic evidence of exposureto dolphin astrovirus was found in both managed-collection and free-ranging dolphins.
In humans, astroviruses are a leading cause of viral diarrhea in young children,1 and astroviruses have been found in 10% of diarrheic cats.2 Although we were unable to attribute clinical signs to the presence of the astroviruses, it is likely that they have the potential to cause enteritis in marine mammal hosts. Their stability in seawater and the diversity found in marine mammals suggests that the marine environment may be important in astroviral ecology.
The authors would like to thank Dr. Pam Yochem as well as the staffs from all of our collaborating institutions. This work was funded by research grant No. N00014-06-1-0250 to HN from the Office of Naval Research.
1. Dennehy P.H., S.M. Nelson, S. Spangenberger, J.S. Noel, S.S. Monroe, and R.I. Glass. 2001. A prospective case-control study of the role of astrovirus in acute diarrhea among hospitalized young children. J Infect Dis 184: 10-15.
2. Marshall J.A., M.L. Kennett, S.M. Rodger, M.J. Studdert, W.L. Thompson, and I.D. Gust. 1987. Virus and virus-like particles in the faeces of cats with and without diarrhoea. Aust Vet J 64: 100-105.