Segmental configuration and putative origin of the reassortant orbivirus, epizootic hemorrhagic disease virus serotype 6, strain Indiana

In 2006, an exotic reassortant orbivirus, epizootic hemorrhagic disease virus serotype 6 (EHDV-6) [strain (Indiana)], was first detected in the United States. To characterize the reassortment configuration of this virus and to conclusively determine the parental virus of each RNA segment, the complete genome of EHDV-6 (Indiana) was sequenced, in addition to the genomes of representative EHDV-6 and EHDV-2 isolates. Based on genomic comparisons to all other EHDV serotypes, we determined that EHDV-6 (Indiana) originated from a reassortment event between the Australian prototype strain of EHDV-6 (CSIRO 753) and the North American topotype of EHDV-2 (Alberta). Additionally, phylogenetic analysis of all EHDV-6 (Indiana) isolates detected in the United States from 2006 to 2010 suggests that the virus may be undergoing continual reassortment with EHDV-2 (Alberta). In 2010, EHDV-6 (CSIRO 753) was detected in Guadeloupe, demonstrating that the parental virus of the reassortment event is circulating in the Caribbean. (C) 2011 Elsevier Inc. All rights reserved.