Molecular epidemiology of Crimean-Congo hemorrhagic fever virus in Turkey: occurrence of local topotype.

The goal of this study was to investigate the molecular epidemiology of Crimean-Congo hemorrhagic fever virus (CCHFV) in Turkey. The study was performed on a total of 48 confirmed human CCHF cases from 2006 to 2008. The majority of the CCHF viral strains in Turkey were found to belong to the European lineage. Local CCHF viral strains are grouped into two main clusters, which can be further divided into two sub-groups. We also identified an AP92-like virus causing clinical disease in Corum (a mid-Anatolian province). Phylogenetic analysis revealed that the most recent CCHFV infections were caused by intrinsic (or native) CCHF viral strains, which we identified as the local topotype. Comparison of deduced amino acid sequences of S-segment RNAs indicated that the local topotype was derived from viruses of previous years, most likely by a low rate recombination. No genetic differences, based on S- and M-segment RNA sequences, were found between human and tick viral isolates. This data suggest that replication of CCHFV in the tick vector, whether Rhiphicephalus spp. or Hyalomma spp., has no effect on the viral genomic structure.