title: Chikungunya virus of Asian and Central/East African genotypes in Malaysia.
abstract: BACKGROUND
  Chikungunya virus (CHIKV) of the Central/East African genotype has caused large outbreaks worldwide in recent years. In Malaysia, limited CHIKV outbreaks of the endemic Asian and imported Central/East African genotypes were reported in 1998 and 2006. Since April 2008, an unprecedented nationwide outbreak has affected Malaysia.
  
  
  OBJECTIVE
  To study the molecular epidemiology of the current Malaysian CHIKV outbreak, and to evaluate cross-neutralisation activity of serum from infected patients against isolates of Asian and Central/East African genotypes.
  
  
  METHODS
  Serum samples were collected from 83 patients presenting in 2008, and tested with PCR for the E1 gene, virus isolation, and for IgM. Phylogenetic analysis was performed on partial E1 gene sequences of 837bp length. Convalescent serum from the current outbreak and Bagan Panchor outbreak (Asian genotype, 2006) were tested for cross-neutralising activity against representative strains from each outbreak.
  
  
  RESULTS
  CHIKV was confirmed in 34 patients (41.0%). The current outbreak strain has the A226V mutation in the E1 structural protein, and grouped with Central/East African isolates from recent global outbreaks. Serum cross-neutralisation activity against both Central/East African and Asian genotypes was observed at titres from 40 to 1280.
  
  
  CONCLUSIONS
  The CHIKV strain causing the largest Malaysian outbreak is of the Central/East African genotype. The presence of the A226V mutation, which enhances transmissibility of CHIKV by Aedes albopictus, may explain the extensive spread especially in rural areas. Serum cross-neutralisation of different genotypes may aid potential vaccines and limit the effect of future outbreaks.
authors.affiliation: Tropical Infectious Diseases Research and Education Centre, Department of Medical Microbiology, Faculty of Medicine, University Malaya, Kuala Lumpur, Malaysia. jicsam@um.edu.my
authors.forename: I-Ching
authors.initials: IC
authors.lastname: Sam
authors.forename: Yoke Fun
authors.initials: YF
authors.lastname: Chan
authors.forename: Shie Yien
authors.initials: SY
authors.lastname: Chan
authors.forename: Shih Keng
authors.initials: SK
authors.lastname: Loong
authors.forename: Hock Khim
authors.initials: HK
authors.lastname: Chin
authors.forename: Poh Sim
authors.initials: PS
authors.lastname: Hooi
authors.forename: Rajasekaram
authors.initials: R
authors.lastname: Ganeswrie
authors.forename: Sazaly
authors.initials: S
authors.lastname: Abubakar
mesh_terms: D018354:Alphavirus Infections / Q000453:epidemiology / Q000821:virology*; D000914:Antibodies, Viral / Q000097:blood; D002646:Chikungunya virus / Q000235:genetics*; D004196:Disease Outbreaks; D005838:Genotype; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood; D008296:Malaysia / Q000453:epidemiology; D017720:Molecular Epidemiology / Q000379:methods; D009500:Neutralization Tests / Q000379:methods; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D014759:Viral Envelope Proteins / Q000235:genetics
chemical_list: D000914:Antibodies, Viral; D007075:Immunoglobulin M; D014759:Viral Envelope Proteins