Abstract
Cetacean morbillivirus (CeMV) is a lethal virus that has caused epizootics throughout the Atlantic Ocean and Mediterranean Sea and has infected thousands of cetaceans since 1987.1,2,3,6 In the Pacific, a few isolated CeMV cases have been detected on the continental margins since 1995.4,5 The first case of CeMV reported in Hawaii was in a Longman's beaked whale (Indopacetus pacificus) that stranded in 2010.7 This case indicated the need to investigate CeMV and the effect it is having on Hawaiian cetacean populations. This research had three primary objectives: 1) to screen the archive of stranded Hawaiian cetacean tissues for CeMV, 2) to characterize the Hawaiian CeMV isolates by obtaining DNA sequences for the phosphoprotein and nucleocapsid gene regions, and 3) to examine the heterogeneous distribution of CeMV in tissues of infected cetaceans. These objectives were designed to address the hypothesis that a novel strain of CeMV exists in Hawaiian stranded cetaceans. For this project, 45 stranded cetaceans from Hawaii Pacific University's stranded cetacean tissue archive were screened for the presence of CeMV using reverse transcription polymerase chain reaction. CeMV was detected in 12 individuals representing 11 different species. Phosphoprotein and nucleocapsid gene nucleotide sequence comparisons strongly suggested that a novel strain of CeMV, Hawaiian cetacean morbillivirus (HMV), is present in Hawaii. The heterogeneity of CeMV within individual lymph nodes was also investigated. The detection rates varied but the likelihood of detecting CeMV may be higher toward the center of lymph nodes. The oldest case of HMV was a humpback whale (Megaptera novaeangliae) that stranded in 1998. Currently, the natural history of the HMV strain is unknown; however, migrating cetaceans may have had a role in the introduction of CeMV to Hawaii. Vertical transmission of CeMV is supported by the detection of HMV in a neonate sperm whale (Physeter macrocephalus) as well as 2 young calves, a spinner dolphin (Stenella longirostris) and a humpback whale (M. novaeangliae). The occurrence of CeMV in Hawaii may be higher than detected in this study because of the difficulties associated with detecting CeMV in cetaceans. This is the first multifaceted examination of CeMV in Hawaii, and it will contribute information critical for the management of Hawaiian cetacean populations.
Acknowledgements
The authors wish to thank the Hawaii Pacific University Marine Mammal Stranding Team volunteers, and stranding assistant Su White for providing samples. The authors thank Dr. Jeremiah Saliki and Dr. Stephanie Venn-Watson for their input on this project. The authors thank the John H. Prescott Stranding Grant, the Trustee's Scholarly Endeavor Program Awards, the Trustee's Scholarship, and the Hawaii Pacific University Scholarship program for financial support of this project.
* Presenting author
+ Student presenter
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