Y Guan

Molecular Detection of a Novel Human Influenza (H1N1) of Pandemic Potential by Conventional and Real-Time Quantitative RT-PCR Assays

Abstract Background: Influenza A viruses are medically important viral pathogens that cause significant mortality and morbidity throughout the world. The recent emergence of a novel human influenza A virus (H1N1) poses a serious health threat. Molecular tests for rapid detection of this virus are urgently needed. Methods: We developed a conventional 1-step RT-PCR assay and a 1-step quantitative real-time RT-PCR assay to detect the novel H1N1 virus, but not the seasonal H1N1 viruses. We also developed an additional real-time RT-PCR that can discriminate the novel H1N1 from other swine and human H1 subtype viruses. Results: All of the assays had detection limits for the positive control in the range of 1.0 × 10−4 to 2.0 × 10−3 of the median tissue culture infective dose. Assay specificities were high, and for the conventional and real-time assays, all negative control samples were negative, including 7 human seasonal H1N1 viruses, 1 human H2N2 virus, 2 human seasonal H3N2 viruses, 1 human H5N1 virus, 7 avian influenza viruses (HA subtypes 4, 5, 7, 8, 9, and 10), and 48 nasopharyngeal aspirates (NPAs) from patients with noninfluenza respiratory diseases; for the assay that discriminates the novel H1N1 from other swine and human H1 subtype viruses, all negative controls were also negative, including 20 control NPAs, 2 seasonal human H1N1 viruses, 2 seasonal human H3N2 viruses, and 2 human H5N1 viruses. Conclusions: These assays appear useful for the rapid diagnosis of cases with the novel H1N1 virus, thereby allowing better pandemic preparedness.

Interspecies transmission of influenza viruses: H5N1 virus and a Hong Kong SAR perspective

This account takes stock of events and involvements, particularly on the avian side of the influenza H5N1 bird flu incident in Hong Kong SAR in 1997. It highlights the role of the chicken in the many live poultry markets as the source of the virus for humans. The slaughter of chicken and other poultry across the SAR seemingly averted an influenza pandemic. This perspective from Hong Kong SAR marks the coming-of-age of acceptance of the role of avian hosts as a source of pandemic human influenza viruses and offers the prospect of providing a good baseline for influenza pandemic preparedness in the future. Improved surveillance is the key. This is illustrated through the H9N2 virus which appears to have provided the replicating genes for the H5N1 virus and which has since been isolated in the SAR from poultry, pigs and humans highlighting its propensity for interspecies transmission.

Two lineages of H9N2 influenza viruses continue to circulate in land-based poultry in Southeastern China

Abstract Background: The transmission of H9N2 influenza viruses to humans and the realization that the A/Hong Kong/156/97-like (H5N1/97-like) internal genome complex is still present in southeastern China necessitated a study of the distribution and characterization of H9N2 viruses in poultry in the Hong Kong SAR in 1999. Methods: Virus isolation, serological identification and genetic analysis. Results: Two lineages of H9N2 influenza viruses were isolated in the live poultry markets and are represented by A/Quail/Hong Kong/G1/97 (Qa/HK/G1/97) and A/Duck/Hong Kong/Y280/97 (Dk/HK/Y280/97). No reassortment between the two H9N2 virus lineages was detected despite their co-circulation in the poultry markets. The Qa/HK/G1/97-like viruses were isolated most frequently from quail and Dk/HK/Y280/97-like viruses from chicken. Conclusion: The high prevalence of quail infected with Qa/HK/G1/97-like virus that contains six gene segments genetically highly related to H5N1/97-like virus emphasizes the need for continued surveillance of mammals including humans for the H9N2 virus.

Potential role of live poultry markets and the environment in human exposure to avian influenza viruses

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Ecology and evolution of H5N1 in birds

(1) Several documented cases of influenza (1) Several documented cases of influenza virus transmission from pigs to humans virus transmission from pigs to humans