Virology
Genetic origin of avian influenza A H7N4 virus causing a case of human infection in China, 2018
Fei Deng, Jiefu Peng, Lunbiao Cui, Xian Qi, Shenjiao Wang, Huiyan Yu, Ke Xu, Xiang Huo, Changjun Bao
Published 2018-09-30
Cite as Chin J Microbiol Immunol, 2018, 38(9): 665-672. DOI: 10.3760/cma.j.issn.0254-5101.2018.09.004
Abstract
ObjectiveTo analyze the molecular characteristics and genetic origin of a novel avian influenza A H7N4 virus casuing a case of human infection in China.
MethodsSpecimens were collected from the patient and chickens and ducks kept by the patient and neighbours and then detected by real-time quantitative PCR. The original specimens and virus isolates were analyzed by next-generation sequencing technology to obtain viral whole-genome sequences. Pairwise sequence alignments and phylogenetic analysis were performed by BLASTs, ClustalX and MEGA 6.1 softwares.
ResultsIn January 2018, a human case infected with avian influenza A H7N4 virus was confirmed. Seven H7N4 viruses were isolated from specimens collected from chicken and ducks kept in the patient`s backyard. H7N4 virus was a novel reassortant virus with all eight gene fragments derived from wild waterfowl in Eurasia. HA protein contained a single basic amino acid residue R in cleavage site, suggesting that H7N4 virus was low pathogenic. The receptor-binding sites of HA had QSG at 226-228 residues, which indicated that the virus retained avian-type receptor specificity (SAα2-3Gal). Different from H7N4 viruses in avian, the virus isolated from the patient had substitution at position 627 (E→K) in PB2 protein, which might increase its adaptation in human host.
ConclusionThis study reported a case of human infection with a novel reassortant avian influenza A H7N4 virus, which revealed that the traditional backyard breeding models might facilitate cross-species transmission of avian influenza viruses in southern China.
Key words:
Avian influenza A virus; H7N4 subtype; Cross-species transmission
Contributor Information
Fei Deng
Jiangsu Provincial Center for Disease Control and Prevention, Nanjing 210009, China
Jiefu Peng
Lunbiao Cui
Xian Qi
Shenjiao Wang
Huiyan Yu
Ke Xu
Xiang Huo
Changjun Bao