Complete L segment coding-region sequences of Crimean Congo hemorrhagic fever virus strains from the Russian...

The large (L) RNA segment of Crimean Congo hemorrhagic fever (CCHF) virus strain AST/TI30908, isolated from pooled Hyalomma marginatum ticks collected in 2002 from the Astrakhan region of European Russia, was amplified piecemeal using reverse-transcription/polymerase chain reaction, followed by direct sequencing of gel-purified amplicons. After removal of 5' and 3' primer-generated termini, the assembled AST/TI30908 L segment sequence is 12112 nucleotides long, with 41.3% G + C content, and is greater than 87% and 96% identical at the nucleotide and translated amino acid levels, respectively, to partial or full-length CCHF virus L segment sequences deposited in GenBank. A complete L segment coding-region sequence for CCHF virus strain TAJ/HU8966, isolated from a patient in Tajikistan in 1990, was determined in a similar fashion. This L segment (12133 nucleotides long, 41.1% G + C content) shares 88% nucleotide identity with the full-length strain Matin from Pakistan, and 97% nucleotide identity with a partial L segment sequence of strain Khodzha from Uzbekistan. Strain TAJ/HU8966 shares at least 96% identity at the translated amino acid level with all other CCHF virus L segment sequences. Although, for the most part, CCHF virus L polyprotein primary sequences are uniformly well conserved, a region of marked variability was identified in the N-terminal half of the RNA-dependent RNA polymerase. This region, approximately 50 amino acids in length, is flanked by previously-reported arenavirus and bunyavirus-conserved regions, and may prove useful in CCHF diagnosis and viral taxonomy.