Reply to Kok and Dwyer

Letter (Correspondence)postprin

Interventions in live poultry markets for the control of avian influenza: A systematic review

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Crouching Tiger, Hidden Dragon: The Laboratory Diagnosis of Severe Acute Respiratory Syndrome

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Protective efficacy of poultry vaccines against recently circulating Highly Pathogenic Avian Influenza (HPAI) H5N1 virus isolater from markets and farms in Hong Kong 2008

Parallel Session 2 - Emerging/Infectious Diseases: no. S7Theme: Translating Health Research into Policy and Practice for Health of the PopulationINTRODUCTION: Highly pathogenic avian influenza (HPAI) H5N1 remains a major threat to animal and public health. Since 2003, Hong Kong has successfully used poultry vaccination as part of its strategy to minimise this threat within Hong Kong. In mid-2008, an HPAI H5N1 outbreak occurred in a vaccinated poultry farm in Hong Kong. AIMS: a) to compare protective efficacy of different poultry vaccines against the 2008 farm outbreak strain; and b) to assess whether there needs to be a change in the poultry vaccine used in Hong Kong. METHODS: White leghorn chickens were raised in a clean laboratory environment and …published_or_final_versio

Use of humanised mice to study antiviral activity of human γδ-T cells against influenza A viruses

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Role of cyclooxygenase-2 in H5N1 viral pathogenesis and the potential use of its inhibitors

1. Cyclooxygenase-2 (COX-2), along with TNF-α and other proinflammatory cytokines, was hyperinduced in H5N1- infected macrophages in vitro and in epithelial cells of autopsied lung tissues of infected patients. 2. The COX-2 mediated amplification of the proinflammatory response is rapid, and the effects elicited by the H5N1-triggered proinflammatory cascade are broader than those arising from direct viral infection. 3. Selective COX-2 inhibitors suppress the H5N1- hyperinduced cytokines in the proinflammatory cascade.published_or_final_versio

Influenza-associated mortality in Hong Kong

Background. The impact of influenza on mortality in countries in subtropical and tropical regions is poorly quantified. Estimation of influenza-related illness in warm-climate regions is more difficult, because the seasonality of virus circulation is less well-defined. Partly as a result of these factors, influenza vaccine is grossly underutilized in the tropics, even for individuals ≥65 years of age. Methods. Weekly numbers of deaths were modeled by Poisson regression, and excess deaths attributable to influenza in Hong Kong were estimated for 1996-1999. Comparison of weekly mortality during periods of influenza predominance and periods of low influenza activity was used to derive an alternative estimate of influenza-associated mortality. Results. Estimates derived from the Poisson model indicated that influenza resulted in 7.3 deaths per 100,000 population per year (95% confidence interval [CI], 3.1-11.4) from cardiorespiratory disease among individuals aged 40-65 years and 102.0 deaths per 100,000 per population per year (95% CI, 61.2-142.7) among individuals aged ≥65 years. Although respiratory diseases accounted for the majority of influenza-related deaths, influenza also contributed to 13.8% (95% CI, 4.8%- 22.7%) and 5.3% (95% CI, 1.2%-9.3%) of deaths related to ischemic heart disease. Conclusion. Influenza is associated with deaths due to ischemic heart disease as well from respiratory diseases. Overall influenza-associated mortality in a region with a warm climate, such as Hong Kong, is comparable with that documented in temperate regions. The need for influenza vaccination in tropical regions needs to be reassessed.published_or_final_versio

Pathogenesis of the novel avian-origin influenza A (H7N9) virus Influenza H7N9 virus in human lower respiratory tract

Poster Session: News and Views from H7N9 OutbreakBackground: As of May 2013, 131 laboratory-confirmed human infections with a novel influenza H7N9 virus had been reported from China. The source of human infection appears to be poultry. There is so far no evidence of sustained human-to-human transmission. Genetic analysis revealed that all eight gene segments of H7N9 were of avian origin; six internal gene segments from avian influenza H7N9 viruses, while hemagglutinin and neuraminidase genes were derived from influenza viruses circulating in ducks and wild ducks, respectively. The emergence of the H7N9 influenza virus catches global attention about whether the new virus could spark another pandemic. The majority of the infected patients were hospitalized and suffered from ARDS, with a fatality rate of about 37%. Our study aimed to determine the mechanism contributing to the pathogenesis of the H7N9 virus. A panel of proinflammatory cytokines and chemokines will be examined upon influenza H7N9 virus infection in alveolar epithelial cells in order to examine if these mediators were induced differentially when compared with the highly pathogenic avian influenza (HPAI) H5N1 and the 2009 pandemic H1N1 virus. Moreover, because cleaved caspase 3 is commonly employed as a marker for the indication of apoptosis, we further examined the extensiveness of cleaved caspase 3 in influenza virus infection in human lung ex vivo cultures. Materials and Methods: Fresh biopsies of human lung tissue were obtained from patients undergoing surgical resection of lung tissues. Lung tissue fragments were cultured with F12K medium incubated at 37°C. For viral infection experiments, influenza viruses A/Shanghai/1/2013 (SH1, H7N9), A/Shanghai/2/2013 (SH2, H7N9), A/Hong Kong/483/97 (H5N1), and A/California/07 (Ca07, H1N1pdm) at a viral titer of 106 TCID50/mL were used for ex vivo lung culture infection. Infected lung tissues were collected in 10% formalin at 24, 48, and 72 hpi for immunohistochemical staining. Costaining of cleaved caspase 3 and influenza virus nucleoprotein was carried out for the detection of apoptosis. Furthermore, primary culture of human alveolar epithelial cells was isolated from human lungs by mincing the lung, followed by filtration and centrifugation. Human alveolar epithelial cells were infected with the novel influenza H7N9, the HPAI H5N1, and the pandemic H1N1 virus. Virus replication was monitored by measuring infectious viral particles using TCID50. mRNA and protein expression of proinflammatory cytokines and chemokines were quantified by real time qPCR and ELISA. Results: We found extensive apoptosis in influenza H7N9 (both SH1 and SH2) and H5N1, but not H1N1pdm infected ex vivo lung tissues, suggesting that both avian influenza viruses can induce apoptosis and cause severe cell death in human lung tissue. Furthermore, unlike HPAI H5N1 which induces dysregulated proinflammatory cytokine responses, the novel influenza H7N9 virus elicited poor proinflammatory cytokine responses, inducing type I and III interferon in ex vivo human lung explant cultures. The novel influenza H7N9 virus is an intrinsically more potent inducer of proinflammatory cytokine than the H1N1pdm virus but less than the H5N1 virus. Conclusions: The proinflammatory cytokine and chemokine responses may contribute modestly to the severity of human H7N9 disease, but it is likely that direct viral cytopathology is probably playing a more important role in pathogenesis of human H7N9 diseases. The recognition of the role of cleaved caspase 3 in severe human infection of avian influenza virus can provide insights on the development of novel therapeutic approaches for the preparedness of the future outbreak of pandemics.published_or_final_versio

Replication and pathogenesis of avian influenza A (H5N1) virus infection in polarised human bronchial and alveolar epithelium

1. In vitro models of polarised human respiratory epithelial cells were established to investigate the tropism and innate host responses of influenza A (H5N1 and H1N1) viruses. 2. Both viruses efficiently infected alveolar epithelial cells of both the apical and basolateral surfaces of the epithelium, whereas release of newly formed virus was mainly from the apical surface of the epithelium. 3. H5N1 virus was a more potent inducer of cytokines and chemokines in alveolar epithelial cells than H1N1 virus. Such chemokines were secreted onto both the apical and basolateral surfaces of the polarised alveolar epithelium. 4. In bronchial epithelium, the H5N1 virus replicated more efficiently and induced a stronger type I interferon response in the undifferentiated NHBE cells than did H1N1 virus. In contrast, in well-differentiated cultures, H5N1 virus replication was less efficient and elicited a lower interferon-beta response than did H1N1 virus. 5. Recombinant virus with vRNPs of a mammalian PB2 and an avian PB1 had the strongest polymerase activities, and replicated better in human cell cultures, especially at a high incubation temperature. These viruses were potent inducers of cytokines and chemokines in primary human alveolar epithelial cells.published_or_final_versio

Human infection with a novel avian influenza A(H5N6) virus

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