Phylodynamics of Crimean Congo hemorrhagic fever virus in South Russia.

Phylodynamics of Crimean Congo Hemorrhagic fever virus (CCHFV) genotype V in South Russia was analyzed using 244 partial (452-571 nt) sequences in all three genomic segments and 38 complete genomic sequences. Despite increased number of sequences, the Russian lineage of the European genotype V (commonly termed GtVa) was distinct from GtV isolates from Turkey and the Balkan countries. No geographic pattern was observed in phylogenetic subgrouping of CCHFV within South Russia. Identical isolates could be found at distant locations spaced by hundreds of kilometers, while relatively divergent viruses circulated in the same region. Full genome analysis indicated that reassortment events within GtVa occurred every few decades (median half-life of a non-reassortant node 30-40 years) and involved M and S segments. Therefore, in South Russia CCHFV represents a highly dynamic population of frequently reassorting viruses.