OBJECTIVETo investigate genotype of wild-type measles viruses circulated in Beijing in 2003.

METHODSThroat swabs specimens were collected from patients seen during an outbreak of measles and from clinically suspected sporadic measles patients in 2003. Vero/SLAM cell lines recommended by WHO were used to isolate measles virus. Four hundreds and fifty nucleotides of COOH-terminal of nucleoprotein (N) genes were amplified by using PR-PCR. The amplified products were sequenced and the sequences were compared with references viruses from GeneBank.

RESULTSEight strains of measles viruses were isolated from throat swabs of patients who came from seven districts and counties of Beijing. Sequence analysis of the 450 nucleotides of COOH-terminal of nucleoprotein (N) genes indicated that these 8 strains belonged to H1a genotype. The average genetic distances of these 8 strains to H1a genotype, Chin9322, H1b genotype, Chin9475 and H1c genotype, Chin9427, were 0.004 - 0.011, 0.026 - 0.031 and 0.015 - 0.022, respectively. The average genetic distances of these 8 strains to H1a genotype, Anhui 01 - 1/Anhui 02 - 2, were 0.000 - 0.009 (0 - 5 nucleotide variation).

CONCLUSIONSMajor genotypes of wild-type measles viruses circulated in Beijing in 2003 were H1a genotype. The genotypes H1c, H1b and H2 may have disappeared in Beijing.