Background:In recent years,avian influenza viruses(AIVs)have seriously threatened human health.Questions such as:why do AIVs infect humans?,how quickly can an AIV become pandemic?,and which virus is the most dangerous...Background:In recent years,avian influenza viruses(AIVs)have seriously threatened human health.Questions such as:why do AIVs infect humans?,how quickly can an AIV become pandemic?,and which virus is the most dangerous?cannot be sufficiently answered using current bioinformatic studies.Method:Secondary structures and energies of representative 5′-untranslated region(UTR)of the HA gene were calculated.Then their secondary structures and energies were re-calculated after one or two nucleotide substitutions were introduced into the HA 5′-UTR.Phylogenetic trees on the basis of hemagglutinin(HA)and polymerase basic protein 2(PB2)amino acid sequences and HA 5′-UTR nucleotide sequences were constructed.The connection between the energy and translation efficiency of 5′-UTR was confirmed by in vitro coupled transcription/translation assay.Results:The simplicity of the secondary structure of the 5′-UTR of the HA gene determines the overall virus replication rate and transmission potential.Point mutation assays show that the 5′-UTR sequences of the HA gene in the influenza subtypes H2N2,H3N2,and H7N9 have greater variation potentials than other virus subtypes.Conclusion:Some high-virulent strains of avian influenza might emerge in the next two to three years.The H2N2 subtype,once disappeared in humans,may stage a comeback.The current outbreak of H7N9 may become pandemic and cause even more deaths,if one or two bases are substituted in the 5′-UTR sequence of the HA gene.展开更多
To elucidate the genetic characterization and molecular epidemiological features of Echovirus 19 （El9） isolates collected from an outbreak associated with hand, foot and mouth disease （HFMD） in Tai＇an city of Sha...To elucidate the genetic characterization and molecular epidemiological features of Echovirus 19 （El9） isolates collected from an outbreak associated with hand, foot and mouth disease （HFMD） in Tai＇an city of Shandong Province of China from July to September, 2003. Methods Thirty seven Echovirus 19 isolates were isolated from stool specimens and throat swabs collected during the outbreak, then major capsid （VP1） genomic sequence was determined, and phylogenetic tree was done based on the VP1 sequences among these 37 and other El9 viruses deposited in the Genbank. Also a representative strain named CHN-SD03-TN12 was selected for sequencing of 5′-untranslated regions （5′-UTR）. Results The identity rate was about 98.9%-100% among all these 37 El9 viruses. The genetic relationships between these 37 El9 isolates and other strains reported were also depicted. The identity rate was about 78.4%-78.9% compared with El9 reference strain Burke. The substitutions in the sequence of 5′-UTR resulted in changes in the conjectural properties of 5′-UTR of El9 viruses. Condusion The genetic features of El9 viruses isolated during the outbreak in Shandong Province in 2003 may be associated with a genetic and antigenic drift that changes the virulence of the Shandong isolates, but the molecular changes in Shandong El9 viruses contributing to their phenotype remain to be further illuminated. However, the sequences described in this paper substantiate the changes taken place in capsid VPI and 5′UTR regions. These substitutions may contribute to their tropism and virulence, and play a significant role in pathogenesis and clinical manifestations of the disease.展开更多
基金We thank LetPub for its linguistic assistance during the preparation of this paper.This work was supported by the National Natural Science Foundation of China(Grant no.31300207)the Preeminent Youth Fund of Sichuan Province(Grant no.2015JQO045)the Support Program of Sichuan Agricultural University(Grant no.03570305).
文摘Background:In recent years,avian influenza viruses(AIVs)have seriously threatened human health.Questions such as:why do AIVs infect humans?,how quickly can an AIV become pandemic?,and which virus is the most dangerous?cannot be sufficiently answered using current bioinformatic studies.Method:Secondary structures and energies of representative 5′-untranslated region(UTR)of the HA gene were calculated.Then their secondary structures and energies were re-calculated after one or two nucleotide substitutions were introduced into the HA 5′-UTR.Phylogenetic trees on the basis of hemagglutinin(HA)and polymerase basic protein 2(PB2)amino acid sequences and HA 5′-UTR nucleotide sequences were constructed.The connection between the energy and translation efficiency of 5′-UTR was confirmed by in vitro coupled transcription/translation assay.Results:The simplicity of the secondary structure of the 5′-UTR of the HA gene determines the overall virus replication rate and transmission potential.Point mutation assays show that the 5′-UTR sequences of the HA gene in the influenza subtypes H2N2,H3N2,and H7N9 have greater variation potentials than other virus subtypes.Conclusion:Some high-virulent strains of avian influenza might emerge in the next two to three years.The H2N2 subtype,once disappeared in humans,may stage a comeback.The current outbreak of H7N9 may become pandemic and cause even more deaths,if one or two bases are substituted in the 5′-UTR sequence of the HA gene.
基金This work was supported by Chinese Center for Disease Control and Prevention and Ministry of Health,China.
文摘To elucidate the genetic characterization and molecular epidemiological features of Echovirus 19 （El9） isolates collected from an outbreak associated with hand, foot and mouth disease （HFMD） in Tai＇an city of Shandong Province of China from July to September, 2003. Methods Thirty seven Echovirus 19 isolates were isolated from stool specimens and throat swabs collected during the outbreak, then major capsid （VP1） genomic sequence was determined, and phylogenetic tree was done based on the VP1 sequences among these 37 and other El9 viruses deposited in the Genbank. Also a representative strain named CHN-SD03-TN12 was selected for sequencing of 5′-untranslated regions （5′-UTR）. Results The identity rate was about 98.9%-100% among all these 37 El9 viruses. The genetic relationships between these 37 El9 isolates and other strains reported were also depicted. The identity rate was about 78.4%-78.9% compared with El9 reference strain Burke. The substitutions in the sequence of 5′-UTR resulted in changes in the conjectural properties of 5′-UTR of El9 viruses. Condusion The genetic features of El9 viruses isolated during the outbreak in Shandong Province in 2003 may be associated with a genetic and antigenic drift that changes the virulence of the Shandong isolates, but the molecular changes in Shandong El9 viruses contributing to their phenotype remain to be further illuminated. However, the sequences described in this paper substantiate the changes taken place in capsid VPI and 5′UTR regions. These substitutions may contribute to their tropism and virulence, and play a significant role in pathogenesis and clinical manifestations of the disease.
