Genetic reassortment indicates a new grouping for tick-borne orbiviruses.

The Kemerovo (KEM) serogroup of tick-borne orbiviruses (Reoviridae family) is currently classified into four antigenic subgroups: KEM, Chenuda (CNU), Great Island (GI), and Wad Medani (WM) (B. M. Gorman, J. Taylor, and P. J. Walker, 1983, In "The Reoviridae," pp. 287-357). Reassortment assays were carried out to determine the potential for gene exchange both within and between subgroups. Genome segment reassortment was demonstrated between members of two subgroups: KEM virus (a human pathogen) and representatives of the GI subgroup (viruses associated with seabirds). Neither KEM nor GI subgroup viruses reassorted with three viruses currently assigned to the CNU subgroup [CNU, Essaouira (ESS), and Mono Lake (ML)]. Within the CNU subgroup, CNU and ESS viruses reassorted, but there was no evidence of genome segment exchange between either of these two viruses and ML virus. The genetic data, and previously published antigenic data, suggest the need for reassigning these viruses. Four new serogroups are proposed to replace the extant KEM serogroup: KEM serogroup (comprising KEM and GI subgroups), CNU serogroup (including CNU and ESS viruses), Mono Lake serogroup, and WM serogroup.