[Analysis on the whole genome of the influenza H1N1 virus of the mild and severe cases in Beijing in 2009].

Objective: To explore the characteristics of the whole genome of the influenza H1N1 virus of the mild and severe cases in Beijing.

Methods: A total of 21 samples of throat swabs were collected from surveillance-designated hospitals between June and December in 2009, including 10 severe cases (4 death cases) and 11 mild cases. RNA of the virus were extracted,and the amplified primers of the whole genome were designed.

[Establishment of a high-throughput respiratory virus detection technology without RNA purification and reverse transcription].

Objective: To establish a convenient and high-throughput respiratory virus detection method to facilitate epidemiological viral monitoring.

Methods: We used high-throughput microsphere-based flexible multi-analyte profiling technology (xMAP) coupled with signal amplification molecules to simultaneously detect RNAs of 8 viruses including influenza viruses A and B, parainfluenza viruses type 1, 2 and 3, respiratory syncytial viruses A and B, and metapneumovirus in a 96-well plate format. The sensitivity and specificity of the method for the synthetic viral RNAs were evaluated.

[Application of EARS in early-warning of influenza pandemic in Beijing].

Objective: To illustrate the efficiency of cumulative sum (CUSUM) in pre-warning of the influenza peak in Beijing.

Methods: CUSUM was used to analyze the data of influenza like illness (ILI), and the results of the influenza laboratory surveillance was regarded as the gold standard to judge the approaching of the influenza peak.

Results: The surveillance was launched in 421 hospitals in Beijing during the 2009 to 2010 influenza season, while the influenza laboratory surveillance was launched by 7 collaborative laboratories.

[The significance of different sample types in study of pandemic A (H1N1) influenza diagnosis].

Objective: To explore the value of different types of samples, including throat swabs, stools, bloods in pandemic A (H1N1) influenza diagnosis and virus shedding patterns.

Methods: From May to June in 2009, 135 samples were collected from 23 confirmed cases of pandemic influenza A (H1N1) infection, including 99 throat swabs, 14 stools, 11 bloods, 1 respiratory tract washing from 13 confirmed cases and 10 blood samples from other confirmed cases. The virus was detected by real-time RT-PCR, the antibody was detected by haemagglutination inhibition assay.

[Etiological characteristics of influenza A (H1N1) 2009 virus in Beijing].

Objective: To analyze the results of detection on influenza A (H1N1) 2009 virus in Beijing from May 2009 to December 2009 and to understand the epidemiologic characteristics during the pandemic period.

Methods: The study was conducted from the May 1 to December 27, 2009. A total of 101 852 throat swab samples were detected with the real-time RT-PCR assay by the Beijing Network Laboratory.

[A survey on serological epidemiology of influenza A (H1N1) 2009 in Beijing].

Objective: To investigate the immunological level against influenza A (H1N1) 2009 in Beijing and provide evidence to evaluate the developing trend of the disease.

Methods: Between Nov. 27, 2009 and Dec.

Serologic survey of pandemic influenza A (H1N1 2009) in Beijing, China.

Objective: To examine the frequency and distribution of antibodies against pandemic influenza A (H1N1 2009) [H1N1] in populations in Beijing and elucidate influencing factors.

Methods: In January 2010, a randomized serologic survey of pandemic influenza A (H1N1 2009) was carried out. Six districts that were randomly selected with a total of 4601 participants involved in the survey have their antibody level tested by hemagglutination inhibition assay.

[Investigation on the source of the first human of avian influenza A (H5N1) case in Beijing].

Objective: To investigate the source of the first human case of avian influenza A (H5N1) infection in Beijing.

Methods: Interviewing the relatives of the case and other key persons, collecting and detecting samples of related biological, epidemiological and environmental data of the case were conducted. Later, the infection source was thoroughly investigated.

RecA-ssDNA filaments supercoil in the presence of single-stranded DNA-binding protein.

Using atomic force microscopy (AFM), we find that RecA-single-stranded DNA (RecA-ssDNA) filaments, in the presence of single-stranded DNA-binding (SSB) protein, organize into left-handed bundles, which differ from the previously reported disordered aggregates formed when SSB is excluded from the reaction. In addition, we see both left- and right-handedness on bundles of two filaments. These two-filament supercoils, individual filaments, and other smaller bundles further organize into more complicated bundles, showing overall left-handedness which cannot be explained by earlier arguments that presumed supercoiling is absent in RecA-ssDNA filaments.

Methods of stretching DNA molecules using flow fields.

Using fluorescence microscopy, we compare the degree of adsorption and stretching of DNA onto surfaces achieved by published stretching methods that use fluid flow: molecular combing, spin-stretching, and air-blowing. Molecular combing uses a receding meniscus to stretch out and deposit the DNA onto a hydrophobic surface. In spin-stretching, we find that the effect of radial hydrodynamic flow created by the centrifugal force of the rotating disk is minimal and that the DNA is stretched out on a hydrophobic substrate by the moving meniscus.

Atomic force microscopic study of aggregation of RecA-DNA nucleoprotein filaments into left-handed supercoiled bundles.

RecA and its complexes with double-stranded DNA (dsDNA) and single-stranded DNA (ssDNA) are responsible for homologous recombination and DNA repair. In this study, we have observed, by atomic force microscopy (AFM), two-filament left-handed superhelices of RecA-dsDNA filaments that further interwind into four- or six-filament bundles, in addition to previously reported left-handed bundles of three or six filaments. Also revealed are four-filament bundles formed by further interwinding of two intrafilament superhelices of individual filaments.