Submitted to: Virus Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/6/2008
Publication Date: 12/1/2008
Citation: McClenahan, S.D., Burek, K.A., Beckmen, K.B., Knowles, N.J., Neill, J.D., Romero, C.H. 2008. Genomic Characterization of Novel Marine Vesiviruses from Steller Sea Lions (Eumetopias jubatus) from Alaska. Virus Research. 138(1-2):26-35. Interpretive Summary: Emerging or newly discovered viruses are becoming more of a threat to both human and animal health. Some of these viruses belong to the calicivirus family of viruses. There is a group of caliciviruses that is present in many different species of marine mammals, called the San Miguel sea lion viruses (SMSV). There is evidence that the marine mammals may be a reservoir for these viruses to enter into domestic livestock herds. To better understand these viruses, 2 new members of the SMSV group of caliciviruses were isolated. These caliciviruses grew well in the laboratory. After complete sequencing of the genomes of these viruses, they were found to be similar in genomic structure to previously characterized SMSV. In addition, these new viruses were found to be antigenically different from previously examined viruses using virus specific antisera. Further research efforts can now be directed toward understanding how these viruses are different and what is changed in the virus particle that confers altered antigenic characteristics. This information will allow researchers to understand the infection process of the caliciviruses and may lead to the design of better vaccines to prevent calicivirus infections.
Technical Abstract: Marine vesiviruses were isolated in cell culture from oral and rectal swabs and vesicular fluids from Alaskan Steller sea lions (SSL; Eumetopias jubatus). Further characterization by RT-PCR, complete genomic sequencing, and phylogenetic analyses indicated that these viruses are most closely related to the marine vesiviruses, but are distinct viruses and represent two novel genotypes. The complete genome of these two SSL isolates was sequenced after cloning their viral cDNA. Both genomes were found to be 8302 nucleotides in length, organized in three open reading frames (ORFs) and contained 5' and 3' untranslated regions (UTR) of 19 and 180 nucleotides, respectively. The complete genomes of both SSL viruses were most closely related to each other and shared 84.0% nucleotide identity. Using the very limited number of complete genomic vesivirus sequences available in the NCBI database, these novel SSL vesiviruses seem most closely related to vesicular exanthema of swine virus-A48 and least related to rabbit vesivirus and walrus calicivirus. Specific antiserum against some evolutionary closer marine vesiviruses did not neutralize these isolates supporting the novel nature of these SSL viruses.