Lack of genetic diversity in Crimean-Congo hemorrhagic fever viruses in Turkey: assessment of present and future patterns of disease.

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne zoonosis which is common in Africa, Asia, Eastern Europe, and the Balkan Peninsula. CCHF has been reported in Turkey with high frequency since 2002. The aim of the present study was to investigate the genetic diversity and genetic relationship between CCHF virus (CCHFV) isolates derived from infected patients over a 2-year period (2009 and 2010) in several provinces of Turkey. Serum samples (n = 48) were selected from CCHFV RNA positive patients and subjected to sequence analysis of the gene regions encoding the S (48 samples) and M (14 samples) segments. The nucleotide sequence alignments showed that the nucleic acid relatedness of CCHFV isolates ranged from 95.7% to 100% and from 93.7% to 100% for S and M segments, respectively. Phylogenetic analysis of both segment sequences revealed that CCHFV isolates circulating in Turkey belonged to the European lineage I and were closely related to the viruses found in the Eastern European-Russian and Balkan Peninsula. The M gene segment-based phylogenetic analysis suggested that 2/14 CCHFV isolates (KYSR3159/09 and YZGT714/10) had additional genetic variations. The results of the present study confirmed that the CCHFV isolates present in Turkey associated with human disease had high genetic homology in S segment, but some variability in the M segment of the RNA.