Study on the stability of SARS-CoV-2 at different temperatures / 上海预防医学

Objective:To observe the stability of severe acute respiratory syrdrome coronavirus （SARS-CoV-2） in cell cultures at different temperatures so as to provide basic data and scientific basis for the research and control of COVID-19 epidemic. Methods:The Vero E6 cells inoculated with SARS-CoV-2. According to TCID50， SARS-CoV-2 with different dilution （10-1， 10-3， 10-5， 10-6）were stored at 37 °C， 22.5 °C， and 4 °C for one to seven days， and then infectious titer was determined by micro cytopathogenic effect assay， observing cytopathic effect （CPE）， and real-time fluorescence quantitative testing. Results:SARS-CoV-2 was stable under 4 °C. The infectivity of high concentration （10-1 dilution） under 22.5 °C for seven days gradually decreased， while lower concentration completely lost infectivity after one day. The virus lost infectivity when stored at 37 °C for more than one day. Conclusion:SARS-CoV-2 is highly stable at 4 °C， sensitive to heat， and related to virus concentration.

Imported B3 genotype measles viruses were isolated from measles cases in the Chinese mainland / 病毒学报

We isolated and identified the genotypes and molecular characteristics of the imported B3 measles virus (MeV) in the Chinese mainland. The Vero/SLAM cell line was used to isolate the viruses. Reverse transcription-polymerase chain reaction was undertaken to amplify the 450 nucleotide acids of the 3-terminal of the nucleoprotein gene. A phylogenetic tree was constructed and similarities in homology assessed. Results suggested that the Shanghai isolates MVi/Shanghai. CHN/38. 13/02 [B3] and MVi/Shanghai. CHN/40. 13/02[B3] were clustered within the same genotype group as the World Health Organization (WHO) B3 genotype reference strain. The number of differences in nucleotide acids between the two Shanghai isolates was one. The homology of nucleotide acids between the Shanghai isolates and the WHO B3 genotype reference strain (MVi/Ibadan. NGA/0.97/1/B3) was 98%. Comparative results from the Measles Nucleotide Surveillance system suggested that the sequences of Shanghai isolates and the 2013 vi- ruses from Australia, Japan, Korea, Hong Kong China, Philippines and Iran were identical. This is the first time that the B3 genotype of MeV in the Chinese mainland has been isolated since 1993. These data can be used to create a "baseline" of genetic information for measles viruses in China, and help to trace the transmission of measles viruses in China and the rest of the world.

Test results analysis on wild measles virus neutralizing antibodies in 70 pairs of mother and infant / 上海预防医学

[Objective] To investigate the level of wild -measles neutralization antibody of both mother and infant , and its correlation between the paired mother and infant . [ Methods] The wild-mea-sles neutralization antibody in the serum of the women and their infants were detected directly by a neutral -ization test (NT) methods. [ Results] The positivity rates of neutralization antibody in mothers and their infants were 91.52%and 88.57%respectively, geometric mean title of neutralization antiboby (GMT) being 61.32 and 58.17 respectively.And the titer of neutralization antibody was highly correlated ( r=0.899, P<0.01)between mother and infant in pairs.When the GMT of mother was ≥1∶16,the positivity rate of neutralization antibody in their infants might reach 100.00%. [ Conclusion] It is important to increase the maternal measles antibody level in order to prevent infants from measles .

Genetic characterization analysis on the first imported measles virus of genotype D8 in Chinese mainland / 病毒学报

This study analyzed the genetic characterization on first imported measles virus of genotype D8 in Chinese mainland. Serums were collected from the suspicious MV patients to detect IgM antibody in ELISA. Throat swabs were cultured in Vero/SLAM cell line to get measles virus isolates. Part of the nucleotide sequence of the 3' terminus of nucleoprotein (N) gene of these isolates were amplified by RT-PCR, and the amplicons were directly sequenced. The phylogenetic analysis was based on the nucleotide sequence about 456 base pairs of the 3' terminus of nucleoprotein (N) gene. Results showed that it reported 1 105 suspicious measles cases in shanghai, 2012, including 590 confirmed cases and 2 clinical case. The reported morbidity was 2.52 per one hundred thousand. 247 measles viruses were isolated from 984 throat swabs specimen. Most of them belonged to sub-genotype H1a except Shanghai12-239 was genotype D8. The homology of nucleotide and amino acid sequences were 97.8% and 98.6% respectively between Shanghai12-239 and WHO reference strain (Manchester. UNK30.94(D8)AF280803). Those were 89.6%-94.5% and 88.7%-95.3% between Shanghai12-239 and WHO reference strains of other genotypes.

Molecular epidemiological analysis of rubella virus isolates from 2001 to 2011 in Shanghai, China / 病毒学报

Throat swabs collected from patients whose serum was measles IgM negative and rubella IgM positive during 2001-2011 were used to conduct cell culture for rubella virus. After identification of cell culture with RT-PCR, nucleotide of gene E1 of rubella virus was amplified and sequenced, followed by molecular epidemiological analysis. A total of 31 rubella viruses were isolated from 60 throat swabs. Compared 27 isolates with the WHO reference strains of all genotypes, phylogenetic tree was constructed based on the amplified 739 nucleotide fragment. These isolates belonged to two different genotypes respectively. Isolates 11009, 11052 and 11106 in 2011 belonged to genotype 2B, and others belonged to genotype 1E. Most of mutations were nonsense mutation, and sequence of amino acid was highly conserved. Amino acid sequence of most isolates of genotype 1E was identical, which suggested rubella viruses from same transmission chain might be transmitted continually since 2001. Rubella virus genotype 2B was found to be popular for the first time in Shanghai in 2011. The nucleotide sequences of these genotype 2B isolates showed 99% identity compared with that of isolates recently from Vietnam, Japan and Argentina. The resources of these strains were not confirmed due to the absence of rubella virus surveillance before.

Human bocavirus in children suffering from acute lower respiratory tract infection in Beijing Children's Hospital / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Human bocavirus (HBoV) is a parvovirus recently found to possibly cause respiratory tract disease in children and adults. This study investigated HBoV infection and its clinical characteristics in children younger than five years of age suffering from acute lower respiratory tract infection in Beijing Children's Hospital.</p><p><b>METHODS</b>Nasopharyngeal aspirates were collected from children suffering from acute lower respiratory tract infection during the winters of 2004 to 2006 (from November through the following February). HBoV was detected by polymerase chain reaction amplification and virus isolation and the amplification products were sequenced for identification.</p><p><b>RESULTS</b>HBoV infection was detected in 16 of 333 study subjects. Coinfections with respiratory syncytial virus were detected in 3 of 16 HBoV positive patients with acute lower respiratory tract infection. The median age for HBoV positive children was 8 months (mean age, 17 months; range, 3 to 57 months). Among the HBoV positive children, 14 were younger than 3 years old, 9 were younger than 1 year old and 7 were younger than 6 months. These 16 positive HBoV children exhibited coughing and abnormal chest radiography findings and more than 60% of these children had wheezing and fever. Ten children were clinically diagnosed with pneumonia, 2 bronchiolitis, 2 acute bronchitis and 2 asthma. One child died.</p><p><b>CONCLUSIONS</b>HBoV was detected in about 5% of children with acute lower respiratory infection seen in Beijing Children's Hospital. Further investigations regarding clinical and epidemiologic characteristics of HBoV infection are needed.</p>