Human Infection with a Novel Avian-Origin Influenza A (H7N9) Virus
15 May 2013-The New England Journal of Medicine (Massachusetts Medical Society)-Vol. 368, Iss: 20, pp 1888-1897
TL;DR: Novel reassortant H7N9 viruses were associated with severe and fatal respiratory disease in three patients, and all three patients died.
Abstract: Background Infection of poultry with influenza A subtype H7 viruses occurs worldwide, but the introduction of this subtype to humans in Asia has not been observed previously. In March 2013, three urban residents of Shanghai or Anhui, China, presented with rapidly progressing lower respiratory tract infections and were found to be infected with a novel reassortant avian-origin influenza A (H7N9) virus. Methods We obtained and analyzed clinical, epidemiologic, and virologic data from these patients. Respiratory specimens were tested for influenza and other respiratory viruses by means of real-time reverse-transcriptase–polymerase-chain-reaction assays, viral culturing, and sequence analyses. Results A novel reassortant avian-origin influenza A (H7N9) virus was isolated from respiratory specimens obtained from all three patients and was identified as H7N9. Sequencing analyses revealed that all the genes from these three viruses were of avian origin, with six internal genes from avian influenza A (H9N2) virus...
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TL;DR: This Article contains typographical errors in Table 2 where ‘Week 2 (N = 32)’ was incorrectly given as ‘week (n’=2’.
Abstract: Scientific Reports 5: Article number: 10942; published online: 01 June 2015; updated: 23 February 2016 This Article contains typographical errors in Table 2 where ‘Week 2 (N = 32)’ was incorrectly given as ‘Week (N = 2)’.
2,328 citations
TL;DR: This poster presents a poster presenting a poster presented at the 2016 International Conference of the Association for the Study of Viral Influenza and its Disruption in China, where it was presented for the first time.
Abstract: Yuelong Shu1, John McCauley2 1. WHO Collaborating Center for Reference and Research on Influenza, Chinese National Influenza Center, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China 2. WHO Collaborating Centre for Reference and Research on Influenza, Crick Worldwide Influenza Centre, the Francis Crick Institute, London, United Kingdom
2,306 citations
Cites background from "Human Infection with a Novel Avian-..."
...WHO Collaborating Center for Reference and Research on Influenza, Chinese National Influenza Center, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China 2....
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...Acceptance of the GISAID sharing mechanism by providers and users of data, and the confidence of the influenza community, were further illustrated in 2013 by the unprecedented immediate release of the genetic sequences of Influenza A(H7N9) viruses from the first human cases, by Chinese scientists at the WHO Collaborating Centre for Influenza in Beijing [11,12]....
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TL;DR: Cross species poultry-to-person transmission of this new reassortant H7N9 virus is associated with severe pneumonia and multiorgan dysfunction in human beings and monitoring of the viral evolution and further study of disease pathogenesis will improve disease management, epidemic control, and pandemic preparedness.
784 citations
TL;DR: Most persons with confirmed H7N9 virus infection had severe lower respiratory tract illness, were epidemiologically unrelated, and had a history of recent exposure to poultry.
Abstract: Background The first identified cases of avian influenza A(H7N9) virus infection in humans occurred in China during February and March 2013. We analyzed data obtained from field investigations to describe the epidemiologic characteristics of H7N9 cases in China identified as of December 1, 2013. Methods Field investigations were conducted for each confirmed case of H7N9 virus infection. A patient was considered to have a confirmed case if the presence of the H7N9 virus was verified by means of real-time reverse-transcriptase–polymerase-chain-reaction assay (RT-PCR), viral isolation, or serologic testing. Information on demographic characteristics, exposure history, and illness timelines was obtained from patients with confirmed cases. Close contacts were monitored for 7 days for symptoms of illness. Throat swabs were obtained from contacts in whom symptoms developed and were tested for the presence of the H7N9 virus by means of real-time RT-PCR. Results Among 139 persons with confirmed H7N9 virus infectio...
613 citations
TL;DR: The presence of a coexisting medical condition was the only independent risk factor for the acute respiratory distress syndrome (ARDS) during the evaluation period, and the novel H7N9 virus caused severe illness, including pneumonia and ARDS, with high rates of ICU admission and death.
Abstract: Background During the spring of 2013, a novel avian-origin influenza A (H7N9) virus emerged and spread among humans in China. Data were lacking on the clinical characteristics of the infections caused by this virus. Methods Using medical charts, we collected data on 111 patients with laboratory-confirmed avian-origin influenza A (H7N9) infection through May 10, 2013. Results Of the 111 patients we studied, 76.6% were admitted to an intensive care unit (ICU), and 27.0% died. The median age was 61 years, and 42.3% were 65 years of age or older; 31.5% were female. A total of 61.3% of the patients had at least one underlying medical condition. Fever and cough were the most common presenting symptoms. On admission, 108 patients (97.3%) had findings consistent with pneumonia. Bilateral ground-glass opacities and consolidation were the typical radiologic findings. Lymphocytopenia was observed in 88.3% of patients, and thrombocytopenia in 73.0%. Treatment with antiviral drugs was initiated in 108 patients (97.3%)...
608 citations
References
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TL;DR: Comparisons to the soluble N-ethyl-maleimide-sensitive factor attachment protein receptor (SNARE) protein complex of vesicle fusion suggests that these molecules are all in the fusion-activated conformation and that the juxtaposition of the membrane anchor and fusion peptide, a recurring feature, is involved in the fused mechanism.
Abstract: Hemagglutinin (HA) is the receptor-binding and membrane fusion glycoprotein of influenza virus and the target for infectivity-neutralizing antibodies. The structures of three conformations of the ectodomain of the 1968 Hong Kong influenza virus HA have been determined by X-ray crystallography: the single-chain precursor, HA0; the metastable neutral-pH conformation found on virus, and the fusion pH-induced conformation. These structures provide a framework for designing and interpreting the results of experiments on the activity of HA in receptor binding, the generation of emerging and reemerging epidemics, and membrane fusion during viral entry. Structures of HA in complex with sialic acid receptor analogs, together with binding experiments, provide details of these low-affinity interactions in terms of the sialic acid substituents recognized and the HA residues involved in recognition. Neutralizing antibody-binding sites surround the receptor-binding pocket on the membrane-distal surface of HA, and the structures of the complexes between neutralizing monoclonal Fabs and HA indicate possible neutralization mechanisms. Cleavage of the biosynthetic precursor HA0 at a prominent loop in its structure primes HA for subsequent activation of membrane fusion at endosomal pH (Figure 1). Priming involves insertion of the fusion peptide into a charged pocket in the precursor; activation requires its extrusion towards the fusion target membrane, as the N terminus of a newly formed trimeric coiled coil, and repositioning of the C-terminal membrane anchor near the fusion peptide at the same end of a rod-shaped molecule. Comparison of this new HA conformation, which has been formed for membrane fusion, with the structures determined for other virus fusion glycoproteins suggests that these molecules are all in the fusion-activated conformation and that the juxtaposition of the membrane anchor and fusion peptide, a recurring feature, is involved in the fusion mechanism. Extension of these comparisons to the soluble N-ethyl-maleimide-sensitive factor attachment protein receptor (SNARE) protein complex of vesicle fusion allows a similar conclusion.
2,629 citations
TL;DR: Avian A/H5N1 influenza viruses can acquire the capacity for airborne transmission between mammals without recombination in an intermediate host and therefore constitute a risk for human pandemic influenza.
Abstract: Highly pathogenic avian influenza A/H5N1 virus can cause morbidity and mortality in humans but thus far has not acquired the ability to be transmitted by aerosol or respiratory droplet ("airborne transmission") between humans. To address the concern that the virus could acquire this ability under natural conditions, we genetically modified A/H5N1 virus by site-directed mutagenesis and subsequent serial passage in ferrets. The genetically modified A/H5N1 virus acquired mutations during passage in ferrets, ultimately becoming airborne transmissible in ferrets. None of the recipient ferrets died after airborne infection with the mutant A/H5N1 viruses. Four amino acid substitutions in the host receptor-binding protein hemagglutinin, and one in the polymerase complex protein basic polymerase 2, were consistently present in airborne-transmitted viruses. The transmissible viruses were sensitive to the antiviral drug oseltamivir and reacted well with antisera raised against H5 influenza vaccine strains. Thus, avian A/H5N1 influenza viruses can acquire the capacity for airborne transmission between mammals without recombination in an intermediate host and therefore constitute a risk for human pandemic influenza.
1,418 citations
TL;DR: Using reverse genetics, it is shown that a mutation at position 627 in the PB2 protein influenced the outcome of infection in mice, and high cleavability of the hemagglutinin glycoprotein was an essential requirement for lethal infection.
Abstract: In 1997, an H5N1 influenza A virus was transmitted from birds to humans in Hong Kong, killing 6 of the 18 people infected. When mice were infected with the human isolates, two virulence groups became apparent. Using reverse genetics, we showed that a mutation at position 627 in the PB2 protein influenced the outcome of infection in mice. Moreover, high cleavability of the hemagglutinin glycoprotein was an essential requirement for lethal infection.
1,267 citations
TL;DR: Results indicate that H5 HA can convert to an HA that supports efficient viral transmission in mammals, and will help individuals conducting surveillance in regions with circulating H5N1 viruses to recognize key residues that predict the pandemic potential of isolate, which will inform the development, production and distribution of effective countermeasures.
Abstract: Highly pathogenic avian H5N1 influenza A viruses occasionally infect humans, but currently do not transmit efficiently among humans. The viral haemagglutinin (HA) protein is a known host-range determinant as it mediates virus binding to hostspecific cellular receptors 1–3 . Here we assess the molecular changes in HA that would allow a virus possessing subtype H5 HA to be transmissible among mammals. We identified a reassortant H5 HA/H1N1 virus—comprising H5 HA (from an H5N1 virus) with four mutations and the remaining seven gene segments from a 2009 pandemic H1N1 virus—that was capable of droplet transmission in a ferret model. The transmissible H5 reassortant virus preferentially recognized human-type receptors, replicated efficiently in ferrets, caused lung lesions and weight loss, but was not highly pathogenic and did not cause mortality. These results indicate that H5 HA can convert to an HA that supports efficient viral transmission in mammals; however, we do not know whether the four mutations in the H5 HA identified here would render a wholly avian H5N1 virus transmissible. The genetic origin of the remaining seven viral gene segments may also critically contribute to transmissibility in mammals. Nevertheless, as H5N1 viruses continue to evolve and infect humans, receptor-binding variants of H5N1 viruses with pandemic potential, including avian–human reassortant viruses as tested here, may emerge. Our findings emphasize the need to prepare for potential pandemics caused by influenza viruses possessing H5 HA, and will help individuals conducting surveillance in regions with circulating H5N1 viruses to
1,255 citations
TL;DR: Because H7N7 viruses have caused disease in mammals, including horses, seals, and humans, on several occasions in the past, they may be unusual in their zoonotic potential and, thus, form a pandemic threat to humans.
Abstract: Highly pathogenic avian influenza A viruses of subtypes H5 and H7 are the causative agents of fowl plague in poultry. Influenza A viruses of subtype H5N1 also caused severe respiratory disease in humans in Hong Kong in 1997 and 2003, including at least seven fatal cases, posing a serious human pandemic threat. Between the end of February and the end of May 2003, a fowl plague outbreak occurred in The Netherlands. A highly pathogenic avian influenza A virus of subtype H7N7, closely related to low pathogenic virus isolates obtained from wild ducks, was isolated from chickens. The same virus was detected subsequently in 86 humans who handled affected poultry and in three of their family members. Of these 89 patients, 78 presented with conjunctivitis, 5 presented with conjunctivitis and influenza-like illness, 2 presented with influenza-like illness, and 4 did not fit the case definitions. Influenza-like illnesses were generally mild, but a fatal case of pneumonia in combination with acute respiratory distress syndrome occurred also. Most virus isolates obtained from humans, including probable secondary cases, had not accumulated significant mutations. However, the virus isolated from the fatal case displayed 14 amino acid substitutions, some of which may be associated with enhanced disease in this case. Because H7N7 viruses have caused disease in mammals, including horses, seals, and humans, on several occasions in the past, they may be unusual in their zoonotic potential and, thus, form a pandemic threat to humans.
1,039 citations