title: Chikungunya virus with E1-A226V mutation causing two outbreaks in 2010, Guangdong, China.
abstract: BACKGROUND
  CHIKV is a mosquito-borne emerging pathogen that has a major health impact in humans in tropical zones around the globe. A new variant of the virus, E1-A226V caused a large outbreak in the Indian Ocean islands and India from 2004-2007. CHIKV outbreak was initially reported in Dongguan region of Guangdong in 2010 in China, another smaller CHIKV outbreak was found in Yangjiang region of Guangdong two weeks later. The viral agent causing the two outbreaks was inferred to be the new E1-A226V variant and Yangjiang CHIKV might be introduced from Dongguan. To confirm the hypothesis and determine the origin of CHIKV causing the outbreaks, we described Yangjiang outbreak in this study, and the molecular characterization of CHIKV from Yangjiang and Dongguang outbreaks were analyzed.
  
  
  RESULTS
  27 clinical cases of CHIK fever were reported in outbreak in Yangjiang region. Sera sample from 12 clinical cases were collected from the outbreak, and nucleic acid and antibody tests for CHIKV were performed using Real-time RT-PCR and indirect immunofluorescence. Positive samples of Real-time RT-PCR were subjected to viral isolation. The results showed 3/12 samples positive for Real-time RT-PCR. 7/12 and 4/12 samples were positive for IgM and IgG against CHIKV respectively, two virus strains were isolated. Four viral genomes from Dongguan and Yangjiang were sequenced, characterized and phylogeneticly analyzed. Phylogenetic analysis revealed that the four seqeunced viruses had the closest relationship (99.4~99.6% identify) with the Singapore 2008 isolate belonging to the Indian ocean clade. A common mutation at the site of the E1-A226V was observed among four viruses. Four and three aa substitutions were detected in the CHIKV sequence from the Dongguan and Yangjiang outbreak strains respectively.
  
  
  CONCLUSIONS
  CHIKV with an E1-A226V mutation that originated from Southeast Asia isolates caused two outbreaks in China in 2010, and originated from two different infectious sources.
authors.affiliation: The Center for Disease Control and Prevention of Guangdong Province, 160 Quxian Road, Dashi Street, Panyu District, Guagnzhou, Guangdong 511430, China.
authors.forename: De
authors.initials: D
authors.lastname: Wu
authors.forename: Yonghui
authors.initials: Y
authors.lastname: Zhang
authors.forename: Qiong
authors.initials: Q
authors.lastname: Zhouhui
authors.forename: Jing
authors.initials: J
authors.lastname: Kou
authors.forename: Wenjia
authors.initials: W
authors.lastname: Liang
authors.forename: Huan
authors.initials: H
authors.lastname: Zhang
authors.forename: Corina
authors.initials: C
authors.lastname: Monagin
authors.forename: Qiaoli
authors.initials: Q
authors.lastname: Zhang
authors.forename: Wenjie
authors.initials: W
authors.lastname: Li
authors.forename: Haojie
authors.initials: H
authors.lastname: Zhong
authors.forename: Jianfeng
authors.initials: J
authors.lastname: He
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.forename: Songwu
authors.initials: S
authors.lastname: Cai
authors.forename: Changwen
authors.initials: C
authors.lastname: Ke
authors.forename: Jinyan
authors.initials: J
authors.lastname: Lin
mesh_terms: D000328:Adult; D000368:Aged; D018354:Alphavirus Infections / Q000453:epidemiology* / Q000821:virology*; D019943:Amino Acid Substitution; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D002646:Chikungunya virus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D002681:China / Q000453:epidemiology; D016000:Cluster Analysis; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D010802:Phylogeny; D012367:RNA, Viral / Q000235:genetics; D017422:Sequence Analysis, DNA; D014764:Viral Proteins / Q000235:genetics*
chemical_list: D000914:Antibodies, Viral; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D012367:RNA, Viral; D014764:Viral Proteins