Isolation and identification of measles virus genotype D9 detected for the first time in Beijing, 2013

Objective To identify the genotype and molecular characteristic of imported measles virus genotype D9. detected for the first time in Beijing. Methods The throat swabs and urine specimens were collected from the suspected imported measles patient to isolate virus by using Vero/SLAM cell line. Fragment of 676 nucleotide acids of the carboxyl end of nucleoprotein gene were amplified with reverse transcription-polymerase chain reaction(RT-PCR), and then the PCR products were directly sequenced and analyzed. The phylogenetic tree was constructed based on 450 nucleotide acids of the carboxyl end of nucleoprotein gene, and homological analysis was performed at nucleotide acid level and amino acid level. Results The isolate BJCY13026-2 was within the same genotype group of WHO genotype D9 reference strain Victoria. AUS 12.99, the homology of nucleotide acid and amino acid was 95.8% and 96% respectively. Compared with other 23 genetype reference strains, the homology of nucleotide acid and amino acid were 88.1%-95.6% and 90.7%-96.7% respectively. Compared with the Chinese measles vaccine strain Shanghai-191, the homology of nucleotide acid and amino acid was 91.1% and 90.0% respectively. Compared with the major circulating measles strain genotype H1a in China, the homology of nucleotide acid and amino acid was 89.4% and 91.3% respectively. Conclusion Measles virus genotype D9 was detected from an imported measles case in Beijing.