ABSTRACT
The highly pathogenic avian influenza A (HPAI) viruses of the H5N1 subtype infect poultry and have also been spreading to humans. Although new antiviral drugs and vaccinations can be effective, rapid detection would be more efficient to control the outbreak of infections. In this study, a phage-display library was applied to select antibody fragments for HPAI strain A/Hubei/1/2010. As a result, three clones were selected and sequenced. A hemagglutinin inhibition assay of the three scFvs revealed that none exhibited hemagglutination inhibition activity towards the H5N1 virus, yet they showed a higher binding affinity for several HPAI H5N1 strains compared with other influenza viruses. An ELISA confirmed that the HA protein was the target of the scFvs, and the results of a protein structure simulation showed that all the selected scFvs bound to the HA2 subunit of the HA protein. In conclusion, the three selected scFVs could be useful for developing a specific detection tool for the surveillance of HPAI epidemic strains.
Subject(s)
Antibody Specificity/immunology , Influenza A Virus, H5N1 Subtype/immunology , Influenza, Human/diagnosis , Influenza, Human/immunology , Single-Chain Antibodies/immunology , Amino Acid Sequence , Animals , Cell Surface Display Techniques , Chickens , Hemagglutination Inhibition Tests , Hemagglutinin Glycoproteins, Influenza Virus/chemistry , Hemagglutinin Glycoproteins, Influenza Virus/immunology , Hemagglutinin Glycoproteins, Influenza Virus/metabolism , Humans , Influenza in Birds , Models, Molecular , Molecular Sequence Data , Mutation , Peptide Library , Protein Binding/immunology , Protein Conformation , Single-Chain Antibodies/chemistry , Single-Chain Antibodies/genetics , Single-Chain Antibodies/metabolismABSTRACT
The molecular characterization and phylogenetic analysis of hemagglutinin (HA) genes of human influenza H3N2 viruses in Guangdong, China from 2007 to 2010 were studied in this study. By space-time sampling of strains, the HA genes of H3N2 strains from Guangdong were sequenced and searched from Internet, and then the variation and evolution of HA genes were conducted by Lasergene 7.1 and Mega 5.05 and evolutionary rates were analyzed by epidemiological data. The phylogenetic tree was established by alignment of 17 Guangdong strains and 26 global reference strains. Ks rates and Ka rates of HA genes were 2.06 x 10(-3)-2.23 x 10(-3) Nt/Year and 1.05 x 10(-3)-1.21 x 10(3) Nt/Year during 2007-2010, while the velocity of HA1 evolution of Ka was 3. 13 times than that of HA2 evolution. Compared with HA of vaccine strain A/Perth/16/2009, the genetic homologies of Guangdong strains in 2009 reached to 98.8%-99.7% and of Guangdong strains in 2010 reached to 98.0%-98.4%. There were some amino acid substitutions in five epitope regions of HA1 during 2007-2010, especially in B region (N160K) and D region (K174R/N); the K189E/N/Q and T228A in RBS (receptor-binding site) occurred in 2010 as two glycoproteins sites substituted impacted on the HA1 antigenicity. The antigenicity of epidemic H3N2 strains in 2010 was to some degree different that of the vaccine strain A/ Perth/16/2009. According to that there were variations of B and D epitopes and two sites of RBS and two glycoprotein in Guangdong H3N2 HA1 genes, WHO/ CDC should recommend new representative strains during 2011-2012 influenza seasons if H3N2 HA genes further evolve in the near future.
Subject(s)
Evolution, Molecular , Hemagglutinin Glycoproteins, Influenza Virus/genetics , Influenza A Virus, H3N2 Subtype/genetics , Amino Acid Substitution , China , Disulfides/chemistry , Epitopes/genetics , Hemagglutinin Glycoproteins, Influenza Virus/chemistry , Hemagglutinin Glycoproteins, Influenza Virus/immunology , Humans , Mutation , PhylogenyABSTRACT
OBJECTIVE: To establish molecular typing of Listeria monocytogenes isolates by pulsed-field gel electrophoresis (PFGE) for studying the epidemiologic characteristics of Listeria monocytogenes isolated from foodstuff in Guangdong province and to build up PFGE typing database of Listeria monocytogenes isolates for identifying the infectious resource of the outbreaks and other epidemiologic investigation. METHODS: "Standardized Protocol for Molecular Subtyping of Listeria monocytogenes by PFGE" was followed. BioNumerics software was applied on image analysis, database establishment, comparative and corresponding analysis. RESULTS: 107 Listeria monocytogenes isolates were typed by PFGE, 41 PFGE types were observed among the isolates. The PFGE types were dispersive among these isolates. Listeria monocytogenes isolates were most frequently isolated in raw chicken while the most PFGE types were found in this type of food. The positive rate was relatively high in cold and iced foods. Only 1-2 DNA fragment difference occurred in 26 Listeria monocytogenes isolates by PFGE, so high degree of relatedness remained among these isolates. There were unique PFGE patterns in the regions of Shaoguan and Huizhou. From time to time, a number of isolates remained close relationship. CONCLUSION: PFGE typing of the 107 Guangdong Listeria monocytogenes isolates demonstrated relative genetic diversity but a number of the isolates showed close relatedness.
