Tahyna virus (TAHV) is a member of the California serogroup of the family Bunyaviridae and the genus Orthobunyavirus . Viruses of the genus Orthobunyavirus are arthropod-borne and possess a single-stranded, negative-sense RNA genome of three segments designated small (S), medium (M), and large (L), which encode the nucleocapsid (N), the surface polyprotein, and the polymerase protein, respectively. Tahyna virus was first isolated in Czechoslovakia in 1958 from a pool of Aedes caspius mosquitoes. 1 Since that time, TAHV has been found and shown to be associated with human illness throughout parts of Europe and Asia. [2][3][4] Typical clinical manifestations of TAHV infection include influenza-like symptoms of fever and respiratory congestion; the infection may also cause acute arthritis, pharyngitis, and complications of the central nervous system.5 Previous studies identified a high level of conservation of the TAHV genome, even though viruses were obtained from temporally distinct regions over a long period. 6,7 In 2006, TAHV was isolated for the first time in the People's Republic of China, and human infection has been confirmed in this country. 8,9 The first TAHV isolate (XJ0625) from China was obtained from Culex sp. mosquitoes in Kashi, Xinjiang. 8 Subsequently, in 2007, two TAHV isolates (XJ0708 and XJ0710) were obtained from separate pools of Aedes vexans mosquitoes obtained in Bayinguoleng, Xinjiang, approximately 900 km east of Kashi. This report describes comprehensive genomic characterization of these TAHV isolates from China. Molecular and phylogenetic analyses of the N protein, polyprotein, and polymerase open reading frames (ORFs) indicate a relatively high level of M segment diversity compared with that of the S and L segments of these TAHVs from China.The TAHV isolates were obtained from mosquito pools. These pools were obtained as part of arthropod-borne virus surveillance efforts in the People's Republic of China. All procedures used were performed according to manufacturer's instructions unless stated otherwise. Mosquitoes were collected in light traps, identified by morphologic characteristics, and separated by genus/species/collection site into pools of up to 50-100 specimens. The pools were triturated in minimal essential medium and clarified by centrifugation. One hundred microliters of resultant supernatants was then added to confluent layers of BHK-21 cells in six-well plates. Inoculated cells were then incubated at 37°C and inspected daily for cytopathic effects. Cells infected with supernatant from mosquito pools XJ0625 (containing 100 Culex mosquitoes that were not identified to species), XJ0708, and XJ0710 (containing 60 and 70 Ae. vexans mosquitoes in each pool, respectively) showed initial signs of cytopathic effects at day one post-inoculation. Supernatants from these cells were collected at day 2 post-inoculation and were inoculated into 25-cm 2 flasks containing BHK-21 cells. Viral RNA was extracted directly from 140 μL of infected, second passage BHK-21 cell culture supern...