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Objective To investigate the molecular evolution of the Hemagglutinin (HA) and Neuraminidase (NA) genes of influenza A/H3N2 viruses in Shenzhen in the first half of 2017, so as to provide scientific basis for predicating influenza epidemic and variation. Methods A total of 40 influenza A/H3N2 viruses strains were selected and the molecular phylogenetic trees were constructed by bioinformatics software DNAStar, MEGA 7.0, etc. Then, the genetic characteristics and variation of HA and NA genes along with corresponding amino acids were analyzed. Results The homology of Shenzhen isolates reached 97.8%-100.0%, which located in the human-derived branch of Asia and North America. Compared with the vaccine strains A/Switzerland/9715293/2013(H3N2) and A/Hong Kong 14801/2014(H3N2) recommended by world Health Oraganication (WHO), there was a higher sequence similarity. Compared with the vaccine strain, HA and NA proteins had a number of amino acid sites replaced, of which HA 6 antigen sites and 2 receptor binding sites change; NA had a mutation of D151N/G located in enzyme activity sites. Potential N-glycosylation sites for HA and NA also changed. Conclusions The influenza A/H3N2 viruses in Shenzhen in the first half of 2017 has not yet formed a new subtype in the epidemic. Currently, the recommended vaccine strains still have some protective effects on the population. The replacement mutation of multiple amino acids sites of HA and NA suggests that the dynamic monitoring of molecular level of influenza A/H3N2 viruses need to be strengthened.
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Objective To investigate the molecular epidemiological characteristics of hemaggluti-nin (HA) and neuraminidase (NA) of influenza B viruses (IBV) isolated in Qingdao from 2011 to 2018. Methods A total of 12236 samples of influenza-like cases in Qingdao from 2011 to 2018 were collected to extract viral RNAs. All samples were screened for influenza A viruses ( IAV) and IBV by one-step multiplex real-time RT-PCR. Lineages of IBV were identified. One hundred and eighty-two strains of IBV were select-ed to amplify HA and NA genes by RT-PCR and then analyzed by sequencing. Phylogenetic analysis and variation analysis of genes and amino acids were carried out. Results IBV was detected almost every year in Qingdao from 2011 to 2018. The positive rate was only slightly lower than that of IAV ( 4. 99％ vs 6. 21％). B/Victoria linkage had two prominent epidemic years (2011-2012, 2015-2016), while B/Yama-gata linkage had three (2013-2014, 2014-2015, 2017-2018). Most of the infected people were children un-der 10 years old, and the people infected with the two lineages had similar age characteristics. Phylogenetic analysis of HA genes showed clusters in Victoria clades of 1A and 1B and Yamagata clades of 2 and 3. IBV of Yamagata lineage had more amino acid mutation sites than those of Victoria lineage in HA genes with grea-ter genetic diversity. The B/Yamagata strains had 12 amino acid mutations and the B/Victoria strains had seven in four major epitopes. In the receptor binding sites, two amino acid mutations were detected in the B/Yamagata strains and three in the B/Victoria strains. In Qingdao, 26 strains of IBV were intra-lineage reas-sortments, mostly of the B/Victoria lineage, and 23 strains were inter-lineage reassortments, mostly between HA-B/Yamagata and NA-B/Victoria strains. A possible resistant strain to NA inhibitor was found. Conclu-sions The significance of IBV in seasonal influenza should not be neglected. Amino acid substitution, in-sertion/deletion and gene reassortment were the main strategies for the natural evolution of IBV. Influenza surveillance was of great importance and influenza vaccine strains needed to be updated in time.
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Objective@#To research the gene characteristics of neuraminidase(NA) gene of influenza A(H1N1) virus of Chongqing from 2011 to 2016.@*Methods@#Forty-three H1N1 influenza virus strains isolated from 2011 to 2016 were chosen according to the different time and places of isolation. NA genetic sections were amplified by RT-PCR and sequenced, and then the sequences of nucleic and amino acid were analyzed.@*Results@#Phylogenetic analysis indicated that the relationship between H1N1 viruses from 2011 to 2016 and the vaccine strain was close to each other. Compared with the vaccine strain A/California/07/2009(H1N1), the homologies in nucleotide and amino acid sequences for NA gene were 97.9%-99.4% and 96.8%-98.9%, respectively. Most of the strains had the same eight potential glycosylation sites as the vaccine strains, and some strains got new potential glycosylation sites at NA protein site 42, while some lost their potential glycosylation sites at NA protein site 386.@*Conclusions@#The changes of H1N1 NA gene had increased year by year, but H1N1 viruses in Chongqing area were still sensitive to Daffy. And monitoring the drug resistant viruses should be strengthened, in order to provide measures against H1N1 viruses.
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Background: A disease outbreak of A (H1N1) PDM09 was reported in Andaman and Nicobar islands in 2009 with an attack rate of 33.5% among settler population and 26.3% among the aboriginal Nicobarese tribe. During the ongoing outbreak of A (H1N1) PDM09 disease in different parts of the world, a subject working in Dubai city of Saudi Arabia, came to Port Blair, following which the pandemic triggered for the fi rst time in these Islands. Materials and Methods: During the period August 2009 to January 2011, 30 confi rmed cases of Infl uenza A (H1N1) PDM09 virus infection was detected. To understand the genetic relationship, the NA gene sequences of the viruses were phylogenetically analysed together along with the virus sequence isolated from other parts of the world. Result: Formation of multiple clusters were observed, with the sequences of Andaman Islands, mainland India, Mexico, Saudi Arabia and few other counties clustering together. The sequence analysis data revealed that there was no specifi c mutation conferring resistance to oseltamivir among the Andaman A (H1N1) PDM09 virus isolates. The result of phylogenetic analysis have also revealed that the A (H1N1) PDM09 virus might have spread in these remote Islands of India via the subject from Saudi Arabia/Dubai. Conclusion: A (H1N1) PDM09 Infl uenza outbreak have highlighted the need to strengthen the region-specifi c pandemic preparedness plans and surveillance strategies.
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Objective To identify the pathogen of an influenza epidemic situation and analyze the genetic characteristic of hemagglutinin( HA ) gene and neuraminidase(NA) gene of this pathogen. Methods Real-time RT-PCR was used to dectect nucleic acid of the pandemic( H1N1 ) 2009 virus from oropharyngeal swabs of initial influenza-like illness in epidemic. The viruses were was inoculated and isolated with embryonated eggs. And the HA gene and NA gene were sequenced to analyze their characteristic. Results The influenza epidemic situation was caused by the pandemic( H1N1 ) 2009 virus. The HA and NA sequences data showed that the virus had the high homology with reference virus, and the NA sequences had not the H274Y mutation. Conclusion In this study, the pandemic( H1N1 ) 2009 virus were similar with the vaccine-like virus and the isolated virus of China, and sensitive to oseltamivir.