title: Mini-genome rescue of Crimean-Congo hemorrhagic fever virus and research into the evolutionary patterns of its untranslated regions.
abstract: Crimean-Congo hemorrhagic fever virus (CCHFV) is a member of genus Nairovirus, family Bunyaviridae, which are distributed widely in Africa, Europe and Asia with several genotypes. As a BSL-4 level pathogen, the requirement of high-level biosafety facilities severely constrains researches on live virus manipulation. In this study, we developed a helper-virus-independent mini-genome rescue system for the Chinese YL04057 strain. Based on the enhanced green fluorescent protein (EGFP)-derived mini-genome plasmids, this polymerase I driven system permits easy observation and quantification. Unlike previous report, gradually reduced levels of activity of the CCHFV L, M and S untranslated regions (UTRs) were observed in our system. We also demonstrated that the UTRs at both ends were indispensable for mini-genome background expression. In addition, we phylogentically analyzed all six UTRs of CCHFV and showed that L-UTRs were clustered together approximately corresponding to their original geographical continents. The UTRs of M segment showed a similar branch structure to its open reading frames (ORFs), and nearly an identical tree was generated with 5' UTRs of S segment compared with its ORFs. However, the 3' UTRs of S segment formed new divergent groups. Compatibility tests of YL04057 strain nucleocapsid protein and L protein expression plasmids with Nigerian strain IbAr10200 mini-genomes revealed lower compatibility of L-UTRs without an obvious effect on M-UTRs. Moreover, we demonstrated that the L-UTRs could tolerate certain nucleotide mutations. This system may provide a foundation for future studies of the viral replication cycle, pathogenic mechanisms and evolutionary patterns of CCHFV.
authors.affiliation: State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, Hubei, China; University of Chinese Academy of Sciences, Beijing 100039, China.
authors.forename: Jiuru
authors.initials: J
authors.lastname: Zhao
authors.forename: Han
authors.initials: H
authors.lastname: Xia
authors.forename: Yujiang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Shiyu
authors.initials: S
authors.lastname: Yin
authors.forename: Zhong
authors.initials: Z
authors.lastname: Zhang
authors.forename: Shuang
authors.initials: S
authors.lastname: Tang
authors.forename: Zheng
authors.initials: Z
authors.lastname: Kou
authors.forename: Jingfeng
authors.initials: J
authors.lastname: Yu
authors.forename: Zhaojun
authors.initials: Z
authors.lastname: Fan
authors.forename: Tianxian
authors.initials: T
authors.lastname: Li
mesh_terms: D000349:Africa; D000818:Animals; D001208:Asia; D002460:Cell Line; D005060:Europe; D019143:Evolution, Molecular; D016679:Genome, Viral; D003225:Hemorrhagic Fever Virus, Crimean-Congo / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D006479:Hemorrhagic Fever, Crimean / Q000821:virology*; D006801:Humans; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010802:Phylogeny; D020506:Untranslated Regions; D014764:Viral Proteins / Q000235:genetics
chemical_list: D020506:Untranslated Regions; D014764:Viral Proteins
keywords: CCHFV; Evolution; Mini-genome system; Untranslated regions