Possible pandemic threat from new reassortment of influenza A(H7N9) virus in China

Meng, Zhefeng; Han, Renzhi; Hu, Yunwen; Yuan, Zhenghong; Jiang, Shibo; Zhang, X.; Xu, Jianqing

doi:10.2807/1560-7917.es2014.19.6.20699

Cited by 24 publications

(26 citation statements)

References 13 publications

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“…With expanded geographic distribution, the H7N9 viruses further reassorted with regional H9N2 viruses and increased their genetic diversity in the internal genes (7)(8)(9). Genetic comparison of human and poultry H7N9 isolates has identified mammalian adaptive mutations; in particular, many of the human H7N9 isolates contained the well-established mammalian adaptive signature K627 or N701 in the PB2 protein, as opposed to the E627 or D701 signature found in avian H7N9 isolates (7,8,10,11).…”

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confidence: 99%

Transmission of H7N9 Influenza Viruses with a Polymorphism at PB2 Residue 627 in Chickens and Ferrets

Luk

Leung

Sia

et al. 2015

J Virol

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Poultry exposure is a major risk factor for human H7N9 zoonotic infections, for which the mode of transmission remains unclear. We studied the transmission of genetically related poultry and human H7N9 influenza viruses differing by four amino acids, including the host determinant PB2 residue 627. A/Silkie chicken/HK/1772/2014 (SCk1772) and A/HK/3263/14 (HK3263) replicated to comparable titers in chickens, with superior oropharyngeal over cloacal shedding; both viruses transmitted efficiently among chickens via direct contact but inefficiently via the airborne route. Interspecies transmission via the airborne route was observed for ferrets exposed to the SCk1772-or HK3263-infected chickens, while low numbers of copies of influenza viral genome were detected in the air, predominantly at particle sizes larger than 4 m. In ferrets, the human isolate HK3263 replicated to higher titers and transmitted more efficiently via direct contact than SCk1772. We monitored "intrahost" and "interhost" adaptive changes at PB2 residue 627 during infection and transmission of the Sck1772 that carried E627 and HK3263 that carried V/K/E polymorphism at 60%, 20%, and 20%, respectively. For SCk1772, positive selection for K627 over E627 was observed in ferrets during the chicken-to-ferret or ferret-to-ferret transmission. For HK3263 that contained V/K/E polymorphism, mixed V627 and E627 genotypes were transmitted among chickens while either V627 or K627 was transmitted to ferrets with a narrow transmission bottleneck. Overall, our results suggest direct contact as the main mode for H7N9 transmission and identify the PB2-V627 genotype with uncompromised fitness and transmissibility in both avian and mammalian species. IMPORTANCEWe studied the modes of H7N9 transmission, as this information is crucial for developing effective control measures for prevention. Using chicken (SCk1772) and human (HK3263) H7N9 isolates that differed by four amino acids, including the host determinant PB2 residue 627, we observed that both viruses transmitted efficiently among chickens via direct contact but inefficiently via the airborne route. Chicken-to-ferret transmission via the airborne route was observed, along with the detection of viral genome in the air at low copy numbers. In ferrets, HK3263 transmitted more efficiently than SCk1772 via direct contact. During the transmission of SCk1772 that contained E and HK3263 that contained V/K/E polymorphism at PB2 residue 627, positive selections of E627 and K627 were observed in chickens and ferrets, respectively. In addition, PB2-V627 was transmitted and stably maintained in both avian and mammalian species. Our results support applying intervention strategies that minimize direct and indirect contact at the poultry markets during epidemics.

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confidence: 99%

Transmission of H7N9 Influenza Viruses with a Polymorphism at PB2 Residue 627 in Chickens and Ferrets

Luk

Leung

Sia

et al. 2015

J Virol

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“…Another report from Wang et al . showed that the Polymerase basic protein 2 (PB2) E627K mutation slightly increased the case fatality rate . To date, there has been no mother‐to‐child transmission report in H7N9 infections.…”

Section: Pathogenesis and Vertical Transmissionmentioning

confidence: 99%

Avian influenza virus in pregnancy

et al. 2016

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The unprecedented epizootic of avian influenza viruses, such as H5N1, H5N6, H7N1 and H10N8, has continued to cause disease in humans in recent years. In 2013, another novel influenza A (H7N9) virus emerged in China, and 30% of those patients died. Pregnant women are particularly susceptible to avian influenza and are more likely to develop severe complications and to die, especially when infection occurs in the middle and late trimesters. Viremia is believed to occur infrequently, and thus vertical transmission induced by avian influenza appears to be rare. However, avian influenza increases the risk of adverse pregnancy outcomes, including spontaneous abortion, preterm birth and fatal distress. This review summarises 39 cases of pregnant women and their fetuses from different countries dating back to 1997, including 11, 15 and 13 infections with H7N9, H5N1 and the 2009 pandemic influenza (H1N1), respectively. We analysed the epidemic features, following the geographical, population and pregnancy trimester distributions; underlying diseases; exposure history; medical timelines; human-to-human transmission; pathogenicity and vertical transmission; antivirus treatments; maternal severity and mortality and pregnancy outcome. The common experiences reported in different countries and areas suggest that early identification and treatment are imperative. In the future, vigilant virologic and epidemiologic surveillance systems should be developed to monitor avian influenza viruses during pregnancy. Furthermore, extensive study on the immune mechanisms should be conducted, as this will guide safe, rational immunomodulatory treatment among this high-risk population. Most importantly, we should develop a universal avian influenza virus vaccine to prevent outbreaks of the different subtypes. Copyright © 2016 John Wiley & Sons, Ltd.

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“…The influenza A(H1N1)pdm09 pandemic [1], the emergence of influenza A(H3N2)v in the United States (US) in 2012 [2] and the more recent emergence of influenza A(H7N9) [3], influenza A(H9N2) [4], influenza A(H10N8) [5] and the novel Middle East respiratory syndrome coronavirus (MERS-CoV) infections in humans in 2013 [6] have highlighted the continual threat to human health from new and emerging respiratory viruses with pandemic potential.…”

Section: Introductionmentioning

confidence: 99%

Future directions for the European influenza reference laboratory network in influenza surveillance

Goddard

Meijer

McCauley³

et al. 2015

Eurosurveillance

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Possible pandemic threat from new reassortment of influenza A(H7N9) virus in China

Cited by 24 publications

References 13 publications

Transmission of H7N9 Influenza Viruses with a Polymorphism at PB2 Residue 627 in Chickens and Ferrets

Transmission of H7N9 Influenza Viruses with a Polymorphism at PB2 Residue 627 in Chickens and Ferrets

Avian influenza virus in pregnancy

Future directions for the European influenza reference laboratory network in influenza surveillance

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