Some recent US Bluetongue virus serotype 3 isolates found outside of Florida indicate evidence of reassortment with endemic co-circulating serotypes

Authors: Schirtzinger, Erin; Jasperson, Dane; OSTLUND, EILEEN - Animal And Plant Health Inspection Service (APHIS); JOHNSON, DONNA - Animal And Plant Health Inspection Service (APHIS); Wilson, William - Bill

Submitted to: Journal of General Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/19/2017
Publication Date: 10/19/2017
Citation: Schirtzinger, E.E., Jasperson, D.C., Ostlund, E.N., Johnson, D.J., Wilson, W.C. 2017. Some recent US Bluetongue virus serotype 3 isolates found outside of Florida indicate evidence of reassortment with endemic co-circulating serotypes. Journal of General Virology. https://doi.org/10.1099/jgv.0.000965.
DOI: https://doi.org/10.1099/jgv.0.000965

Interpretive Summary: Bluetongue is an endemic insect-transmitted viral disease of livestock in the United States. There are multiple types of the virus and only five types are considered endemic to the US. New types have been found in the Southeastern US but only one has moved out of the southeast more than once. This study examined the whole virus genomes of several virus isolated and demonstrated that two genetic lineages have been found in the US.

Technical Abstract: Since 1999, eleven serotypes of bluetongue virus (BTV) similar to Central American or Caribbean strains have been isolated in the southeastern United States, predominantly in Florida. The majority of the incursive serotypes have remained restricted to the southeastern US. In recent years BTV serotype 3 (BTV-3) has been isolated in areas increasingly distant from Florida. The current study uses whole genome sequencing of recent and historical BTV-3 isolates from the US, Central American and the Caribbean with additional sequences from GenBank to conduct phylogenetic analyses of the individual segments of the BTV genome to determine if the recent BTV-3 isolates are reassortants with local endemic strains or if they retain a Central American/Caribbean signature. The analyses indicate that BTV-3 isolates from Mississippi 2006, Arkansas 2008 and Mississippi 2009 have very similar evolutionary histories with Mississippi 2006 and Arkansas 2008 being nearly identical. These three isolates contain 7 segments that cluster with those of US endemic BTV serotypes. In contrast, the BTV-3 South Dakota 2012 isolate has a majority of segments that are more similar to other BTV-3 isolates from Florida. The different genetic histories of the BTV-3 isolates suggest that there are at least two different lineages of BTV-3 that are currently circulating in the US.