A variable region in the Crimean-Congo hemorrhagic fever virus L segment distinguishes between strains isolated from different geographic regions.

Alignment of Crimean-Congo hemorrhagic fever virus (CCHFV) L genome segment full-length sequences reveals an overall high level of conservation among strains, with greater than 90% of translated amino acid residues strictly conserved. However, a region of marked variability identified previously, corresponding to L polyprotein amino acid positions 760-810, shares only 40% overall identity between strains. The variable regions sequences of 16 laboratory-adapted CCHFV strains were determined, including 11 strains from European Russia, one strain from Bulgaria, and four strains from the Central Asian countries of Tajikistan, Turkmenistan, and Uzbekistan. Phylogenetic analysis demonstrates this L segment variable region sequence divides CCHFV strains into similar geographically-defined groupings observed for S segment-derived trees, but with higher bootstrap support and a much smaller character set required for analysis.