Type and subtype distribution of influenza virus and genetic evolution of hemagglutinin in Shanghai area in duration of 2004 - 2008 / 中华预防医学杂志

<p><b>OBJECTIVE</b>To analyze the type and subtype distribution of influenza virus and the genetic evolution of hemagglutinin (HA) in Shanghai area during 2004 to 2008.</p><p><b>METHODS</b>All 962 throat swabs were collected from influenza-like patients in 5 influenza sentry hospitals and influenza outbreaks. Influenza viruses were isolated in MDCK cell lines, and then viral types and subtypes were identified. The HA of influenza A isolates selected by outbreak or sporadic patients in different areas and epidemic seasons were sequenced and analyzed by phylogenetic trees.</p><p><b>RESULTS</b>A/H3N2, accounting for 54.9% (162/295), was the dominate subtype in recent years, but less popular in the end of 2005 to the middle of 2006 with 0% (0/16)and 23.5% (8/34) of positive specimen, respectively. There were more A/H1N1 isolates in 2005 - 2006 with 21.4% (12/56), 43.8% (7/16) and 76.5% (26/34) of positive specimen, respectively, but declined obviously in 2007 - 2008 accounting for only 0% (0/44) and 5.0% (7/139). Influenza B virus was more popular in 2004 to 2005 with 42.9% (24/56) and 56.2% (9/16), respectively, and not isolated from 2006 to 2007, then increased in 2008 accounting for 34.5% (48/139). Phylogenetic tree of HA showed that A/H1N1 isolates in the same year clustered from 2005 to 2008, and most A/H3N2 isolated were homologous in the same year during 2004 - 2008 while some were inserted to the clusters of near years and more distinguished sequences appeared. A/H1N1 and A/H3N2 isolates were all similar to the vaccine strains recommended by WHO.</p><p><b>CONCLUSION</b>The distribution of influenza type and subtype kept on changing each year, but A/H3N2 dominated in most years. A/H1N1 and A/H3N2 in the same year clustered, but some A/H3N2 of near years were and evolved faster with more distinguished strains appeared in same interval. Generally, HA of influenza A isolates in Shanghai during 2004 to 2008 were similar to the WHO reference strains.</p>

Sequence analysis on measles viruses isolated in Shanghai in 2005 / 中华流行病学杂志

<p><b>OBJECTIVE</b>To ascertain the genetic characterization and genotype of measles viruses isolated in Shanghai region, in 2005.</p><p><b>METHODS</b>Measles virus was isolated from throat swab specimens collected from suspected measles cases and 450 bp fragment of C terminus of nucleprotein (N) gene was amplified by RT-PCR. Sequence analysis was conducted to ascertain the genotype and to compare the difference of nucleotide with other measles virus strain published in GenBank.</p><p><b>RESULTS</b>4 measles viruses were isolated from 10 throat swab specimens, and the sequence analysis indicated that they belonged to H1 genotype. The homogeneity of 450 nucleotides in the C terminal of the N gene was at 98%-98.2% as compared to H1 genotype (China93-7). They differed from genotype H2 (China94-1) at 6.4%-6.9% and from genotype A (Edmonston) at 6.7%-6.9%, from measles vaccine (Shanghail91) at 7.6%-8.0%. They differed from the other measles viral strain isolated in China in 1993 - 2005 at 0.2%-3.7%. The variation within 4 isolated measles viruses was at 0.7%-1.3%.</p><p><b>CONCLUSION</b>It was H1 genotype measles viruses,which are the native viruses in China that led to the outbreak of measles in Shanghai, in 2005.</p>