scholarly journals Genetic tuning of the novel avian influenza A(H7N9) virus during interspecies transmission, China, 2013

2014 ◽  
Vol 19 (25) ◽  
Author(s):  
D Wang ◽  
L Yang ◽  
R Gao ◽  
X Zhang ◽  
Y Tan ◽  
...  
Keyword(s):  
Amino Acid ◽  
Avian Influenza ◽  
Influenza A ◽  
Case Fatality ◽  
Host Adaptation ◽  
Human Infection ◽  
Interspecies Transmission ◽  
H7n9 Virus ◽  
Binding Preference ◽  
Genetic Tuning

A novel avian influenza A(H7N9) virus causing human infection emerged in February 2013 in China. To elucidate the mechanism of interspecies transmission, we compared the signature amino acids of avian influenza A(H7N9) viruses from human and non-human hosts and analysed the reassortants of 146 influenza A(H7N9) viruses with full genome sequences. We propose a genetic tuning procedure with continuous amino acid substitutions and reassorting that mediates host adaptation and interspecies transmission. When the early influenza A(H7N9) virus, containing ancestor haemagglutinin (HA) and neuraminidase (NA) genes similar to A/Shanghai/05 virus, circulated in waterfowl and transmitted to terrestrial poultry, it acquired an NA stalk deletion at amino acid positions 69 to 73. Then, receptor binding preference was tuned to increase the affinity to human-like receptors through HA G186V and Q226L mutations in terrestrial poultry. Additional mammalian adaptations such as PB2 E627K were selected in humans. The continual reassortation between H7N9 and H9N2 viruses resulted in multiple genotypes for further host adaptation. When we analysed a potential association of mutations and reassortants with clinical outcome, only the PB2 E627K mutation slightly increased the case fatality rate. Genetic tuning may create opportunities for further adaptation of influenza A(H7N9) and its potential to cause a pandemic.

scholarly journals Avian Influenza H7N9 Virus Adaptation to Human Hosts

Viruses ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 871
Author(s):  
Swan Tan ◽  
Muhammad Farhan Sjaugi ◽  
Siew Chinn Fong ◽  
Li Chuin Chong ◽  
Hadia Syahirah Abd Raman ◽  
...  
Keyword(s):  
Amino Acid ◽  
Avian Influenza ◽  
Human Infection ◽  
Amino Acid Substitutions ◽  
Human Adaptation ◽  
H7n9 Virus ◽  
Avian Virus ◽  
Human Viruses ◽  
Virus Adaptation ◽  
Influenza H7n9 Virus

Avian influenza virus A (H7N9), after circulating in avian hosts for decades, was identified as a human pathogen in 2013. Herein, amino acid substitutions possibly essential for human adaptation were identified by comparing the 4706 aligned overlapping nonamer position sequences (1–9, 2–10, etc.) of the reported 2014 and 2017 avian and human H7N9 datasets. The initial set of virus sequences (as of year 2014) exhibited a total of 109 avian-to-human (A2H) signature amino acid substitutions. Each represented the most prevalent substitution at a given avian virus nonamer position that was selectively adapted as the corresponding index (most prevalent sequence) of the human viruses. The majority of these avian substitutions were long-standing in the evolution of H7N9, and only 17 were first detected in 2013 as possibly essential for the initial human adaptation. Strikingly, continued evolution of the avian H7N9 virus has resulted in avian and human protein sequences that are almost identical. This rapid and continued adaptation of the avian H7N9 virus to the human host, with near identity of the avian and human viruses, is associated with increased human infection and a predicted greater risk of human-to-human transmission.

scholarly journals Biological characterisation of the emerged highly pathogenic avian influenza (HPAI) A(H7N9) viruses in humans, in mainland China, 2016 to 2017

2017 ◽  
Vol 22 (19) ◽  
Author(s):  
Wenfei Zhu ◽  
Jianfang Zhou ◽  
Zi Li ◽  
Lei Yang ◽  
Xiyan Li ◽  
...  
Keyword(s):  
Avian Influenza ◽  
Influenza A ◽  
Highly Pathogenic Avian Influenza ◽  
Mainland China ◽  
H7n9 Virus ◽  
Highly Pathogenic ◽  
Pathogenic Avian Influenza ◽  
Binding Preference ◽  
Severe Infections ◽  
Epidemic Wave

With no or low virulence in poultry, avian influenza A(H7N9) virus has caused severe infections in humans. In the current fifth epidemic wave, a highly pathogenic avian influenza (HPAI) H7N9 virus emerged. The insertion of four amino acids (KRTA) at the haemagglutinin (HA) cleavage site enabled trypsin-independent infectivity of this virus. Although maintaining dual receptor-binding preference, its HA antigenicity was distinct from low-pathogenic avian influenza A(H7N9). The neuraminidase substitution R292K conferred a multidrug resistance phenotype.

scholarly journals Emergence of human avian influenza A(H7N9) virus infections in Wenshan City in Southwest China, 2017

2019 ◽  
Author(s):  
Li Jiang ◽  
Xiaonan Zhao ◽  
Wen Xu ◽  
Xuehua Zhou ◽  
Chunrui Luo ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Avian Influenza ◽  
Influenza A ◽  
Human Infection ◽  
Viral Gene ◽  
H7n9 Virus ◽  
Genetic Sequencing ◽  
Live Poultry ◽  
Virus Spreading ◽  
Live Poultry Markets

Abstract Background: The emergence of human infection with avian influenza A(H7N9) virus was reported in Wenshan City, southwestern China in 2017. The study describes the epidemiological and virological features of the outbreak and discusses the origin of the infection. Methods: Poultry exposure and timelines of key events for each patient were collected. Samples derived from the patients, their close contacts, and environments were tested for influenza A(H7N9) virus by real-time reverse transcription polymerase chain reaction. Genetic sequencing and phylogenetic analysis were also conducted. Results: Five patients were reported in the outbreak. An epidemiological investigation showed that all patients had been exposed at live poultry markets. Virus isolates from these patients had low pathogenicity in avian species. Both epidemiological investigations of chicken sources and phylogenetic analysis of viral gene sequences indicated that the source of infection was from Guangxi Province. Conclusions: The transmission route spanned a long geographical region, with virus spreading from east to west. Chickens were an important carrier in the H7N9 virus spreading from Guangxi to Wenshan. Hygienic management of live poultry markets and virological screening of chickens transported across regions should be reinforced to limit the spread of H7N9 virus.

scholarly journals Epidemiologic characterization of 30 confirmed cases of human infection with avian influenza A(H7N9) virus in Hangzhou, China

2014 ◽  
Vol 14 (1) ◽  
Author(s):  
Hua Ding ◽  
Li Xie ◽  
Zhou Sun ◽  
Qing-Jun Kao ◽  
Ren-Jie Huang ◽  
...  
Keyword(s):  
Avian Influenza ◽  
Influenza A ◽  
Human Infection ◽  
H7n9 Virus

Epidemiology of human infections with avian influenza A(H7N9) virus in the two waves before and after October 2013 in Zhejiang province, China

2014 ◽  
Vol 143 (9) ◽  
pp. 1839-1845 ◽  
Author(s):  
X. Y. WANG ◽  
C. L. CHAI ◽  
F. D. LI ◽  
F. HE ◽  
Z. YU ◽  
...  
Keyword(s):  
Avian Influenza ◽  
Influenza A ◽  
Case Fatality ◽  
Zhejiang Province ◽  
H7n9 Virus ◽  
Virus Infections ◽  
Before And After ◽  
Live Poultry ◽  
Second Wave ◽  
Live Poultry Markets

SUMMARYWe compared the epidemiological and clinical features of avian influenza A(H7N9) virus infections in the population in Zhejiang province, China, between March and April 2013 (first wave) and October 2013 and February 2014 (second wave). No statistical difference was found for age, sex, occupation, presence of underlying conditions, exposure history, white blood cell count, lymphocyte percentage and illness timeline and duration (all P > 0·05). The virus spread to 30 new counties compared to the first wave. The case-fatality rate was 22% in the first wave and 42% in the second (P = 0·023). Of those infected, 66% in the first wave and 62% in the second wave had underlying conditions. The proportion of those exposed to live poultry markets were 80% and 66%, respectively. We recommend permanent closure of live poultry markets and reformation of poultry supply and sales.

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