Objective Eight functional fragments of the novel A/H1N1 influenza pandemic virus in 2009 had their own evolutionary characteristics.Among them,the hemagglutinin(HA),the major antigenic gene,was originated from swine influenza virus epidemics in North America.The HA gene,polymerase genes(PB2,PB1 and PA),nucleoprotein gene(NP) and nonstructural protein gene(NS) of the virus strain isolated in Iowa of US in 2005 shared close homology(identities more than 90%) with the corresponding sequences of the novel A/H1N1 influenza pandemic virus in 2009.The Iowa strain might be an intermediate step of the evolutionary process of this novel A/H1N1 influenza virus.The evolutionary process of the novel A/H1N1 influenza might be realized in pigs re-assorted with the neuraminidase(NA) gene from European swine H1N1 influenza virus and matrix proteins(M1 and M2) genes from European H3N2 swine influenza virus.The present paper presented possible evolutionary processes of the novel A/H1N1 influenza pandemic virus in 2009,and pointed out several relevant scientific points which should be emphasized in the prevention and control of the epidemics of the novel A/H1N1 influenza in near future.

Infrastructures of the active surveillance system of emergent public health events consists of the following factors: cases of infectious diseases, symptoms in the Emergency Department of hospitals, etiological examination in the public health laboratories, medication sales and medical supplies sales, public symptoms in metropolitan, absenteeism in elementary and middle schools, animal death, medical emergency service, and unexplained deaths, etc . Active surveillance is able to discover emergent public health events promptly and provide evidences for initiating immediate response system and public health crisis management in China. Research on active surveillance of the emergent public health event should be enforced.

The epidemic of severe acute respiratory syndrome(SARS) leads both to close cooperation and fierce competition in related researches globally. In March 2003, scientists from Hong Kong (China), America, Canada and German discovered a new type of coronavirus in SARS patients(SARS CoV) successively. And it was acknowledged by the WHO. Later, from April to May 2003, researchers from America, German, Chinese Hong Kong, Canada and Dutch published their findings about SARS pathogen in journals like Science, New England Journal of Medicine, The Lancet and Nature, etc . The gene map, complete genome sequence and molecular model of SARS CoV were reported, which has laid a sound foundation for SARS diagnosis, treatment and the development of vaccine. We can learn a lot from the rapid reaction of the related institutes, and the experience gained will benefit us in the future.

Based on the experience in combating severe acute respiratory syndrome(SARS) epidemic in Beijing, the paper analyzed the reasons for the SARS outbreak in Beijing and investigated the government reaction mechanism during emergency. The results showed that there were many defects in dealing with outburst of health event in the current system of public health for disease control, such as lack of the differentiation and prevention at the early stage, misconducts of the epidemic situation report system, lack of professional commanding system and the effective cooperation among the interrelated departments, weak team spirit,unconsciousness of intellectaul property right in the scientific research, and unreasonable medical resource allocation and storage system. Improvements concerning the above problems have been put forward to establish public health reaction mechanism for an emergent situation in China, providing contending for scholars and reference for the decision makers.

Objective: To investigate the first appearance and geographic distribution of hantaviruses in China. Methods: Some sequences of M segment of hantaviruses isolated in China were retrieved from GenBank. Some recently sequenced viruses which have not been registered in GenBank were obtained from authors who reported them. Program MEGA 3. 1 was employed for the phylogenetic analysis of the above virus sequences. Nucleotide divergence rates were estimated by comparing the closely related sister sequences isolated in the same geographical region at no less than a 5-year interval. Based on these calculated divergence rates, together with their isolating time and region, we explored the first appearance and geographic distribution of hantaviruses in China. Results and conclusion: The distribution of hantaviruses was in cluster, with Guizhou Province having the most subgenotypes. which supports the previous hypothesis that hantaviruses first appeared in Guizhou Province of China. A novel subgenotype virus was found in Anhui Province, indicating that it might be easier for the virus to have mutation in Anhui Province. We also found that Gou3 strain might be the earliest one to separate from a common ancestral strain; it is speculated that hantaviruses migrated in China about 315 years ago.

A single intraperitoneal injection (ip) of Astragalus polysaccharide (APS), polysaccharide of Acanthopanax senticosus (PAS) and Lychtm barbamm polysaccharide (LBP) at a dose of up to 10 mg/kg body weight could render splenocytes of adult C57BL/6 mice proliferate significantly higher than normal saline (NS)control. Splenocytes of LBP treated aged mice were 4 times higher than those of NS control of aged mice. The splenocytes of the mice treated with APS, PAS, LBP and NS were incubated with 125 - 1 000 U/ml rIL-2 for 4d in vitro, respectively. The cytotoxicity of LAK cells from the splenocytes of APS, PAS and LBP treated adult mice, in 18 h [125I]UdR release assay, were 70% ~ 120%, 20% -90%, 26% ~ 80% higher than that of the NS control, respectively. The dose of rIL-2 was reduced 75%, 50%, 50%, respectively, in vitro. The cytolytic activities of LAK cells from the splenocytes of LBP treated aged mice were 120%-200% higher than those of the NS control, and the dosage of rIL-2 was decreased more than 75% in vitro.

Adult Kunming mice were immunized with K562 and P815 by a single intraperitoneai injection at a dose of 5?104 cells/murine/d. Anti-P815 and anti-K562 antisera were prepared. Contents of anti-tumor antibodies in the antisera were proved to be high by means of ELISA assay. Splenocytes of C57BL/6 mice and peripheral blood lymphocytes (PBL) from cancer patients were incubated with 125-1000 U/ml IL-2 for 4d. Anti-P815 activity of the LAK cells from C57BL/6 splenocytes was greatly enhanced in the presence of anti-P815 anti-serum at the early stage of culture of LAK and P815 together in 18h [125I]UdR release assay. Anti-K562 activity of LAK cells from PBL was also greatly enlianced by anti-K562 antiserum when the antiserum was added at the early stage of culture. Anti-tumor antibodies in the antisera, not complement and other cytokines, were responsible for the augmentation of NK and LAK cell activities.

Since the first reported case of swine influenza A in Mexico,a total of 15 510 cases have been confirmed in 53 countries by May 29,2009.On April 29,2009,the World Health Organization(WHO)raised its pandemic alert from grade 4 to grade 5.The virus is described as a new subtype of A/H1N1 and is not detected in pigs or humans previously.The virus is sensitive to oseltamivir and zanamivir,but resistant to amantadine and rimantadine.The genetics of the virus are so novel that humans are unlikely to have much immunity to it.The virus can transmit from human to human;therefore it is necessary to enforce quarantine measure for close contactors because the virus transmits during latency.Precaution methods like covering noses and mouths with a tissue when coughing or sneezing can reduce the transmission opportunity.Hands should be washed frequently with soap,especially after coughing or sneezing.Public places with ventilation conditions,personal health behavior and health condition are critical for the prevention and control of this epidemic.

Several epidemic influenza viruses leading to worldwide periodical pandemics all result from the genetic reassortment of different influenza viruses.The novel 2009 A/H1N1 virus is a reassortment virus evolved from swine influenza virus A/H1N1,avian influenza virus H5N1,and human influenza virus A/H1N1.The 8 fragmente genes of the novel A/H1N1 virus had their own evolutionary characteristics.All the pandemic viruses in humans originate from avian influenza viruses and are transferred into humans after reassortment processes in pigs.Pigs as middle host and a mixing vessel of influenza A virus play an important role in the evolution of the 2009 novel A/H1N1 virus.More attention should be paid on the role of swine in the prevention and control of novel H1N1 virus epidemics in future.

Objective To establish a loop-mediated isothermal amplification (LAMP) assay for rapid detection of the West Nile virus (WNV).Methods WNV genome (position nt 1 021 to nt 1 240) was synthesized by a PCR-based gene synthesis method.The synthetic fragments included 6 pairs of LAMP primer recognizing 8 primer sites of WNV genome.The LAMP gene amplification was carried out using a real-time PCR system at 63℃ for 60 min,then the amplification was terminated at 80℃ after 2 min.The amplification products were observed by agarose gel electrophoresis.The sensitivity and specificity of LAMP assay were compared with those of conventional PCR.Results The LAMP assay took less than 20 min,and the amplification product took on a ladder-like electrophoresis pattern.The sensitivity of LAMP assay was 10-fold higher than that of conventional PCR,and the detection limit of LAMP was 9.23 copies/?l.The specificity of WNV-specific LAMP assay was demonstrated by the negative amplification results from dengue virus and Japanese encephalitis virus,both were closely related members of the Flavivirus family.Conclusion LAMP assay is rapid,cost-effective,highly sensitive and specific in detecting genes of interest,and is of great significance for WNV surveillance,especially for grass root units and on-sport surveillance.