Origin and future distribution of the new A (H1N1) influenza virus emerging in North America in 2009

Influenza A (H1N1) transmission by road traffic between cities and towns

Influenza A (H1N1) was spread widely between cities and towns by road traffic and had a major impact on public health in China in 2009. Understanding regulation of its transmission is of great significance with urbanization ongoing and for mitigation of damage by the epidemic. We analyzed influenza A (H1N1) spatiotemporal transmission and risk factors along roads in Changsha, and combined diffusion velocity and floating population size to construct an epidemic diffusion model to simulate its transmission between cities and towns. The results showed that areas along the highways and road intersections had a higher incidence rate than other areas. Expressways and county roads played an important role in the rapid development stage and the epidemic peak, respectively, and intercity bus stations showed a high risk of disease transmission. The model simulates the intensity and center of disease outbreaks in cities and towns, and provides a more complete simulation of the disease spatiotemporal process than other models.

The novel H1N1 Influenza A global airline transmission and early warning without travel containments

A novel influenza A (H1N1) has been spreading worldwide. Early studies implied that international air travels might be key cause of a severe potential pandemic without appropriate containments. In this study, early outbreaks in Mexico and some cities of United States were used to estimate the preliminary epidemic parameters by applying adjusted SEIR epidemiological model, indicating transmissibility infectivity of the virus. According to the findings, a new spatial allocation model totally based on the real-time airline data was established to assess the potential spreading of H1N1 from Mexico to the world. Our estimates find the basic reproductive number R0 of H1N1 is around 3.4, and the effective reproductive number fall sharply by effective containment strategies. The finding also implies Spain, Canada, France, Panama, Peru are the most possible country to be involved in severe endemic H1N1 spreading.

Emergency surveillance of influenza during 2009 in the Chinese city of Qingdao

Please cite this paper as: Wang et al. (2010) Emergency surveillance of influenza during 2009 in the Chinese city of Qingdao. Influenza and Other Respiratory Viruses 5(1), 53–59.

Background  In April, 2009, a new influenza pandemic caused by a swine‐origin H1N1 subtype influenza virus was imminent. We thereby carried out an emergency surveillance study in a Chinese city of Qingdao.

Methods  Pharyngeal swab samples were collected from four targeted groups and tested by reverse‐transcription polymerase chain reaction. Each laboratory‐confirmed pandemic H1N1 case or cluster was investigated, and the hemagglutinin genes of some of the viruses were sequenced and analyzed.

Results  A total of 140 pandemic H1N1 cases including 92 from 7 clusters were identified in the four targeted groups. None of them developed into severe infections. Meanwhile, 103 cases of seasonal influenza (98 H3N2 and 5 H1N1) and 10 clusters of seasonal H3N2 influenza were also identified. Among them, 38 pandemic H1N1 and two seasonal H3N2 influenza cases were air travellers, suggesting that air travel facilitates the spread of pandemic and seasonal influenza even in the northern hemisphere summer. In addition, it was found that pandemic H1N1 and seasonal H3N2 influenza viruses co‐circulated in two clusters. No significant mutations were found in the hemagglutinin gene sequences of pandemic H1N1 viruses, but the seasonal H3N2 influenza viruses have become genetically distinguishable from those circulating in 2007–2008.

Molecular simulation study of the binding mechanism of [α-PTi2W10O40]7- for its promising broad-spectrum inhibitory activity to FluV-A neuraminidase

Polyoxometalate (POM) has promising antiviral activities. It shows broad-spectrum inhibiting ability, high efficiency, and low toxicity. Experimental assays show that titanium containing polyoxotungstates have anti-influenza-virus activity. In this paper, the binding mechanisms of five isomers of di-Ti-substituted polyoxotungstate, [α-1,2-PTi₂W₁₀O₄₀]^7- (α-1,2), [α-1,6-PTi₂W₁₀O₄₀]^7- (α-1,6), [α-1,5-PTi₂W₁₀O₄₀]^7- (α-1,5), [α-1,4-PTi₂W₁₀O₄₀]^7- (α-1,4) and [α-1,11-PTi₂W₁₀O₄₀]^7- (α-1,11), to five subtypes of influenza virus A neuraminidase (FluV-A NA) were investigated in the context of aqueous solution by using molecular docking and molecular dynamics studies. The results show that the isomer α-1,2 is superior to other isomers as a potential inhibitor to neuraminidase. The positively charged arginine residues around the active site of NA could be induced by negatively charged POM to adapt themselves and could form salt bridge interactions and hydrogen bond interactions with POM. The binding free energies of POM/NA complexes range from -5.36 to -8.31 kcal mol^-1. The electrostatic interactions are found to be the driving force during the binding process of POM to NA. The conformational analysis shows that POM tends to bind primarily with N1 and N8 at the edge of the active pocket, which causes the conformational change of the pincers structure comprising residue 347 and loop 150. Whereas, the active pockets of N2, N9 and N4 are found to be more spacious, which allows POM to enter into the active pockets directly and anchor there firmly. This study shows that negatively charged ligand as POM could induce the reorganization of the active site of NA and highlights POM as a promising inhibitor to NA despite the ever increasing mutants of NA.

Electronic Supplementary Material

Supplementary material is available for this article at 10.1007/s11434-010-3271-8 and is accessible for authorized users.

A SYBR Green I real-time RT-PCR assay for detection and differentiation of influenza A(H1N1) virus in swine populations

The novel influenza A(H1N1) virus that emerged recently in Mexico has spread rapidly to many countries and initiated a human pandemic. It would be interesting to determine whether the virus has existed in, or will spread to, the swine population. However, it is difficult to differentiate the virus from some swine influenza viruses. In this study, a SYBR Green I real-time RT-PCR assay was designed for detection and differentiation of influenza A(H1N1) virus from some swine influenza viruses, by comparing the amplification of two pairs of primers corresponding to influenza A(H1N1) virus and some swine influenza viruses, respectively. The assay was evaluated using online analysis, identified influenza viruses and clinical samples. The results indicated that the assay has high sensitivity and specificity to detect influenza A(H1N1) virus, and is able to differentiate it from some swine influenza viruses. This, in turn, could provide essential epidemiological information for risk analysis and decision making in combating the disease, and stimulate research to differentiate pathogens similar to each other using the same method.