human infection caused by an avian influenza a h7n9 virus with a polybasic cleavage site in taiwan 2017

+ MODEL Journal of the Formosan Medical Association (2017) xx, 1e3 Available online at www.sciencedirect.com ScienceDirect journal homepage: www.jfma-online.com CORRESPONDENCE Human infection caused by an avian influenza A (H7N9) virus with a polybasic cleavage site in Taiwan, 2017 Ji-Rong Yang, Ming-Tsan Liu* Center for Diagnostics and Vaccine Development, Centers for Disease Control, Taipei, Taiwan Received 20 February 2017; accepted 21 February 2017 On February 4, 2017, the Centers for Disease Control, Taiwan reported the year’s first laboratory-confirmed human infection with avian influenza A (H7N9) virus, by three real-time reverse transcriptase polymerase chain reactions targeting three different segments of the matrix (M), hemagglutinin (HA), and neuraminidase (NA) genes The patient is a 69-year old man who returned from the Guangdong province of mainland China and is currently in critical condition The avian influenza A virus was first identified in March 2013 in China, and it was found to cause a severe infection in humans.1 In this report, the virus (A/ Taiwan/1/2017) was isolated from a sputum specimen of the patient by inoculating into embryonated chicken eggs The full-length genomic sequences were analyzed to investigate the phylogenetic and genetic characteristics of this virus (GISAID accession numbers EPI917062-EPI917069) We constructed the phylogenetic trees for each genome segment using the program MEGA6 (Tempe, Arizona, United States) Based on the analyzed phylogenies, the A/Taiwan/ 1/2017 virus is a novel reassortant belonging to a genotype whose genetic constellation has not been reported Conflicts of interest: The authors have no conflicts of interest relevant to this article * Corresponding author Center for Diagnostics and Vaccine Development, Centers for Disease Control, Number 161, Kun-Yang Street, Taipei, 11561, Taiwan E-mail address: mtliu@cdc.gov.tw (M.-T Liu) previously The HA and NA genes of this virus belong to the Yangtze River Delta lineage, along with the H7N9 viruses isolated from Jiangsu, Zhejiang, and Fujian provinces of China in 2016 and 2017 This lineage is distinguished from the Pearl River Delta lineage that mainly comprises the virus strains isolated from Hong Kong and Guangdong province since 2014 Phylogenies of the six internal genes of A/Taiwan/1/2017 revealed the viral PB1 and MP (matrix protein) genes located at clades together with those of the A/Anhui/1/2013 vaccine strain and recently isolated viruses from Jiangsu, Zhejiang, Fujian, and Guangdong provinces in 2016 and 2017 The PB2 (polymerase basic protein 2), PA (polymerase acidic protein), and NS (non-structural protein) genes clustered together with early H7N9 viruses and could be separated from those of the 2016 and 2017 viruses These results indicate that the H7N9 viruses are continuously evolving through reassortment The molecular signatures of the A/Taiwan/1/2017 virus associated with host adaptation, receptor specificity, pathogenesis, and antiviral resistance were also investigated (Table 1) The Q226L/I and G228S substitutions in the HA protein, which are the major two mutations contributing to the high-affinity binding of viruses to human receptors, were not identified in this virus However, several substitutions in HA were detected, namely S138A, T160A, and G186V Of particular note, the A/Taiwan/1/2017 virus has an insertion of three basic amino acid residues (RKR) at the cleavage site connecting the HA1 and HA2 peptide regions, carrying a signature (PKRKRTAR/GLF) of highly pathogenic avian influenza (HPAI) viruses This has been the first demonstration of http://dx.doi.org/10.1016/j.jfma.2017.02.011 0929-6646/Copyright ª 2017, Formosan Medical Association Published by Elsevier Taiwan LLC This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Please cite this article in press as: Yang J-R, Liu M-T, Human infection caused by an avian influenza A (H7N9) virus with a polybasic cleavage site in Taiwan, 2017, Journal of the Formosan Medical Association (2017), http://dx.doi.org/10.1016/j.jfma.2017.02.011 + MODEL J.-R Yang, M.-T Liu Table Molecular analysis of the imported A/Taiwan/1/2017 H7N9 virus Determination of viral characteristics Protein Position PB2 PB1 PB1-F2 PA HA(H3 numbering) NA(N2 numbering) M2 NS1 Mutation A/TW/1/2017 Function 627 E/K 701 D/N 702 K/R 368 I/V 66 N/S 87e90 aa in length 100 V/A 336 L/M 356 K/R 409 S/N Cleavage site Basic aa insertion 138 S/A K D K V N 90 aa A L R N PEVP KRKR TARGL A 160 T/A A 186 G/V V 226 Q/L Q 228 G/S G 119 222 292 31 42 92 205 210 E/V I/L R/K S/N P/S D/E N/S G/R E I K N S D S G Replication ability Nuclear Import Species-associated signature positions Increased transmission in ferrets Induction of apoptosis Increased pathogenicity in mice Species-associated signature positions Increased polymerase activity in mice Species-associated signature positions Species-associated signature positions High pathogenesis in poultry Increased binding to human-type influenza receptor N-glycosylation loss and increased binding to human-type influenza receptor Increased binding to human-type influenza receptor Increased binding to human-type influenza receptor Increased binding to human-type influenza receptor Oseltamivir resistance Oseltamivir resistance Resistance to oseltamivir and zanamivir Amantadine resistance Increased pathogenesis in mice Altered virulence in mice Altered antiviral response in host Altered antiviral response in host aa Z amino acids; HA Z hemagglutinin; H3 Z hemagglutinin subtype 3; M2 Z matrix protein; NA Z neuraminidase; N2 Z neuraminidase subtype 2; NS Z non-structural protein; PA Z polymerase acidic protein; PB Z polymerase basic protein; PB1-F2 Z polymerase basic protein alternate reading frame such a molecular characteristic in an H7N9 virus since their emergence in 2013, according to the alignment of viral HA sequences available from the GISAID database In the PB2 protein, the E627K substitution was present, as in previous isolates.1,2 Virulence-related signatures, such as the 90 amino acid-PB1-F2 protein, as well as the P42S and D92E substitutions in the NS1 protein, were also identified The R292K substitution in the NA protein, which is a signature related to antiviral drug susceptibility, was present in the A/ Taiwan/1/2017 virus, suggesting that this virus had developed resistance to oseltamivir The relationship of these substitutions and the viral phenotype in avian and human populations remains unknown The polybasic HA cleavage site is considered the primary virulence marker of HPAI viruses.3 The low pathogenic avian influenza subtypes H5 and H7 acquired multiple basic amino acids at the HA cleavage site after the viruses were introduced into domestic poultry.4 The early H7N9 viruses lacked the polybasic HA cleavage site, exhibiting low pathogenicity, and caused mild or no disease in poultry.1,5 Based on our analysis, we found that the H7N9 virus acquired an additional three basic amino acids at the HA cleavage site for the first time, which probably increased its virulence in poultry We proposed that the acquired polybasic insertion in this virus may be attributed to persistent circulation in poultry species, and the H7N9-infected poultry may be the primary source of human infection Further investigation is needed to determine whether the polybasic HA cleavage site of the H7N9 virus is associated with more severe human disease Our results on the molecular characteristics of this novel H7N9 virus highlight challenges in risk assessment of the H7N9 virus at the human-animal interface References Gao R, Cao B, Hu Y, Feng Z, Wang D, Hu W, et al Human infection with a novel avian-origin influenza A (H7N9) virus N Engl J Med 2013;368:1888e97 Yang JR, Kuo CY, Huang HY, Wu FT, Huang YL, Cheng CY, et al Characterization of influenza A (H7N9) viruses isolated from human cases imported into Taiwan PLoS One 2015;10:e0119792 Horimoto T, Kawaoka Y Reverse genetics provides direct evidence for a correlation of hemagglutinin cleavability and virulence of an avian influenza A virus J Virol 1994;68: 3120e8 Please cite this article in press as: Yang J-R, Liu M-T, Human infection caused by an avian influenza A (H7N9) virus with a polybasic cleavage site in Taiwan, 2017, Journal of the Formosan Medical Association (2017), http://dx.doi.org/10.1016/j.jfma.2017.02.011 + MODEL Human infection caused by an avian influenza A (H7N9) Horimoto T, Rivera E, Pearson J, Senne D, Krauss S, Kawaoka Y, et al Origin and molecular changes associated with emergence of a highly pathogenic H5N2 influenza virus in Mexico Virology 1995;213:223e30 Chen Y, Liang W, Yang S, Wu N, Gao H, Sheng J, et al Human infections with the emerging avian influenza A H7N9 virus from wet market poultry: clinical analysis and characterisation of viral genome Lancet 2013;381:1916e25 Please cite this article in press as: Yang J-R, Liu M-T, Human infection caused by an avian influenza A (H7N9) virus with a polybasic cleavage site in Taiwan, 2017, Journal of the Formosan Medical Association (2017), http://dx.doi.org/10.1016/j.jfma.2017.02.011 ... 2013;381:1916e25 Please cite this article in press as: Yang J-R, Liu M-T, Human infection caused by an avian influenza A (H7N9) virus with a polybasic cleavage site in Taiwan, 2017, Journal of the Formosan Medical... and virulence of an avian influenza A virus J Virol 1994;68: 3120e8 Please cite this article in press as: Yang J-R, Liu M-T, Human infection caused by an avian influenza A (H7N9) virus with a. .. a polybasic cleavage site in Taiwan, 2017, Journal of the Formosan Medical Association (2017) , http://dx.doi.org/10.1016/j.jfma .2017. 02.011 + MODEL Human infection caused by an avian influenza