Genetic analysis of chikungunya viruses imported to mainland China in 2008.
BACKGROUND
Chikungunya virus (CHIKV) has caused large outbreaks worldwide in recent years, especially on the islands of the Indian Ocean and India. The virus is transmitted by mosquitoes (Aedes aegypti), which are widespread in China, with an especially high population density in southern China. Analyses of full-length viral sequences revealed the acquisition of a single adaptive mutation providing a selective advantage for the transmission of CHIKV by this species. No outbreaks due to the local transmission of CHIKV have been reported in China, and no cases of importation were detected on mainland China before 2008. We followed the spread of imported CHIKV in southern China and analyzed the genetic character of the detected viruses to evaluate their potential for evolution.


RESULTS
The importation of CHIKV to mainland China was first detected in 2008. The genomic sequences of four of the imported viruses were identified, and phylogenetic analysis demonstrated that the sequences were clustered in the Indian Ocean group; however, seven amino acid changes were detected in the nonstructural protein-coding region, and five amino acid changes were noted in the structural protein-coding regions. In particular, a novel substitution in E2 was detected (K252Q), which may impact the neurovirulence of CHIKV. The adaptive mutation A226V in E1 was observed in two imported cases of chikungunya disease.


CONCLUSIONS
Laboratory-confirmed CHIKV infections among travelers visiting China in 2008 were presented, new mutations in the viral nucleic acids and proteins may represent adaptive mutations for human or mosquito hosts.
Zheng
Kui
K
State Key Laboratory for Molecular Virology and Genetic Engineering, Institute for Viral Disease Control and Prevention, China CDC, 100 Yingxinjie, Xuanwu District, Beijing 100052, China.
Li
Jiandong
J
Zhang
Quanfu
Q
Liang
Mifang
M
Li
Chuan
C
Lin
Miao
M
Huang
Jicheng
J
Li
Hua
H
Xiang
Dapeng
D
Wang
Ninlan
N
Hong
Ye
Y
Huang
Li
L
Li
Xiaobo
X
Pan
Deguan
D
Song
Wei
W
Dai
Jun
J
Guo
Boxuan
B
Li
Dexin
D
D000328:Adult; D018354:Alphavirus Infections / Q000453:epidemiology* / Q000821:virology*; D019943:Amino Acid Substitution / Q000235:genetics; D002646:Chikungunya virus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification*; D002681:China / Q000453:epidemiology; D016000:Cluster Analysis; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D010802:Phylogeny; D012367:RNA, Viral / Q000235:genetics*; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D014195:Travel; D014764:Viral Proteins / Q000235:genetics
D012367:RNA, Viral; D014764:Viral Proteins