Abstract

Picobirnaviruses are segmented double-stranded RNA viruses. They are poorly understood, and a recent (13 Feb 2012) PubMed search found only 65 publications using the keyword "picobirnavirus." Most reports are in association with diarrhea in a variety of species, and some evidence exists that they cross species.¹ We have recently discovered picobirnaviruses in California sea lions (Zalophus californianus) with diarrhea. To assess the potential of these viruses to cause disease, we developed a specific quantitative PCR (qPCR) assay for the detection and quantitation of these viruses in California sea lion fecal specimens. The qPCR assays accurately detected 10 to 10⁶ cDNA copies. A total of 82 fecal samples from 64 California sea lions were collected from a managed population housed in open water pens and from free-ranging sea lions in California. California sea lion picobirnavirus 1 was detected in 50% of the samples. California sea lion picobirnavirus 2 was detected in 5% of the samples. To compare viral presence and load by fecal consistency, 37 samples were selected. Seventeen fecal samples were characterized as soft and 20 characterized as normal. Fifty-nine percent of soft fecal samples were picobirnavirus-1 positive, compared to 65% of normal fecal samples. There was not a significant difference in fecal viral loads when comparing the two populations. Further analysis needs to be done to determine the significance of these viruses.

Acknowledgements

Research was funded by grant No. N00014-09-1-0252 from the Office of Naval Research to HHN and JFXW and research grant No. N66001-08-D-0070 from the Department of Defense to PKY. Additional funding was provided by The Darden Restaurants, Inc. Foundation, the Bob Baker Foundation, and the Boeing Corporation. Field sampling was conducted under authorization of Marine Mammal Permit Nos. 486-1790-00 and 486-1790-01 to Dr. Brent S. Stewart (HSWRI) and was approved by the HSWRI IACUC. We would like to thank the staff of the U.S. Navy Marine Mammal Program and Dr. B. Stewart for their help with sample collection, the Naval Base Ventura County and SNI/OLF for facilitating research at San Nicolas Island, and Linda Archer, Jennifer Burchell and Celeste Benham for their assistance in the laboratory.

References

1.  Ganesh B, Nataraju SM, Rajendran K, et al. Detection of closely related picobirnaviruses among diarrhoeic children in Kolkata: evidence of zoonoses? Infect Genet Evol. 2010;10:511–516.