To study the biological characteristics and mutations of influenza A(H1N1)pdm09 virus isolated from one case of pneumonia of unknown etiology (PUE),which would provide references for clinical treatment and disease control,the throat swab specimen from the PUE case was isolated in the Madin-Darby Canine Kidney (MDCK) cells,and then the antigenicity,pathogenicity and drug resistance of influenza A (H1N1) pdm09 virus were analyzed after sequencing.As a result,one influenza virus strain was isolated from the specimen and named as A/FujianGulou/SWL64/2016(H1N1).The similarities of nucleotide sequences and amino acids sequences compared with the vaccine strain A/California/07/2009 (H1N1) were 96.9％-98.9％ and 96.7％-99.5％,respectively.Eighteen amino acids had mutated in the HA and 4 mutations,K163Q,S185T,S203T and D222N,were involved in 3 different epitopes,which indicated that the antigenic drift had occurred in the influenza virus.The D222N mutation associated with receptor binding site made the virus infect lower respiratory tract more easily.The virus was still amantadine-resistance and oseltamivir-sensitive.In conclusion,the influenza A (H1N1) pdm09 virus in this study have occurred antigenic drift and has the molecular characterization of causing severe pneumonia,so further surveillance should be performed to prevent and control the influenza epidemic.

Objective To investigate the genetic characteristics and mutations in hemagglutinin ( HA) genes of influenza A subtype H3N2 viruses isolated in Fujian province during 2014—2016. Methods HA gene fragments of 44 randomly selected influenza A (H3N2) viruses were amplified by RT-PCR and then sequenced by Sanger sequencing. Obtained sequences were analyzed by bioinformatics software and on-line websites. Results Pair-wise similarity among HA genes of the 44 strains was between 97. 3%-100. 0% at nucleotide level. The average variations between epidemic strains and corresponding vaccine strains in the year of 2014, 2015 and 2016 were 0. 012, 0. 008 and 0. 009, respectively. The genotype of epidemic strains in 2014 was 3C. 3a rather than 3C. 1 of the vaccine strain. Notably, variations at some antigenic sites, re-ceptor binding sites ( RBSs) and N-Glycosylation sites were identified despite the fact that the genotypes were identical between epidemic and vaccine strains in 2015 and 2016. Conclusion Variations at the HA genes of influenza A (H3N2) viruses in Fujian province occurred during the year of 2014—2016, reflecting the ability of circulating strains to escape the vaccine-induced immunity. Sustainable influenza surveillance and prompt identification of viral variants would benefit influenza prevention and control.

Objective: In this study, we tested for the presence of four human coronaviruses (HCoVs) in children with respiratory tract disease in Fuzhou, Fujian, China. Methods: Nasopharyngeal aspirates were collected from children with respiratory tract disease from Nov, 2007 to Jan, 2015. A total of 266 clinical samples were tested for HCoVs using reverse-transcription polymerase chain reaction (RT-PCR). The positive products were sequenced and compared with those in GenBank by BLAST. The positive samples were then tested for HCoV-HKU1 and HCoV-NL63 using RT-PCR method . We compared the 440 bp pol gene sequence of the 8 HCoV isolates in Fuzhou, China to other HCoV isolates documented in the GenBank database by using MEGA software version 6.06 and the neighbor-joining method . Results: HCoVs were detected in 8 patients (3.0%) out of the 266 children. Two of 266 (0.38%) were positive for HCoV-HKU1; 1 of 266(0.38%)were positive for HCoV-NL63; 1 of 266 (0.38%) were positive for HCoV-229E; 4 of 266 (1.5%)were positive for HCoV-OC43. All of children who were positive for HCoV had respiratory illness. Two HCoV-HKU1 were found to co-infect with human parainfluenza virus type 3 (HPIV-3). The 8 HCoV strains in our study fell into four clusters. Two strains of HCoV-HKU1 were genotype A. Conclusions HCoV infections were probably associated with upper and lower respiratory illness in children. Additional studies are needed to investigate the potential roles of these HCoVs in diseases.