To analyze the antigenic and genetic characteristics of the influenza A (H3N2) virus in mainland China during the surveillance year of 2013-2014, the antigenic characteristics of H3N2 virus were analyzed using reference ferret anti-sera. The nucleotide sequences of the viruses were determined by Sanger dideoxy sequencing, phylogenetic trees were constructed with the neighbor-joining method, and the genetic characteristics of the viruses were determined in comparison to current vaccine strains. The results showed that most of the H3N2 viruses were antigenically closely related to the A/Victoria/361/2011 vaccine strain cell-propagated prototype virus (99.6%). Using the A/Texas/50/2012 egg isolate as the reference antigen, 15.1% of the viruses were found to be closely antigenically related to it, while 11.9% of strains were closely antigenically related to the egg-propagated epidemic strain, A/Shanghai-Changning/1507/2012. Phylogenetic analysis of HA genes indicated that the A(H3N2) viruses in this surveillance year were in the same clade, but no drug resistant mutation was identified in the NA genes. During the 2013-2014 influenza surveillance year, no significant genetic change was detected in either the HA or NA genes of the A(H3N2) viruses, while significant mutations were found in egg isolates resulting from their adaptation during propagation in eggs. The antigenic and genetic changes should be investigated in a timely manner to enable the selection of an appropriate vaccine strain in China.
Animals ; Antigenic Variation ; Base Sequence ; Chick Embryo ; China ; Genetic Variation ; Hemagglutinin Glycoproteins, Influenza Virus ; genetics ; immunology ; Humans ; Influenza A Virus, H3N2 Subtype ; genetics ; immunology ; isolation & purification ; Influenza, Human ; virology ; Molecular Sequence Data ; Mutation ; Phylogeny

Pertussis is a representative vaccine-preventable disease. However, there have been recent outbreaks in countries where even higher vaccination against the disease. One reason is the emergence of antigenic variants, which are different to vaccine type. In Korea, reported cases have rapidly increased since 2009. Therefore, we analyzed genotype of strains isolated in 2011-2012 by multilocus sequence typing method. As expected, the genotype profiles of tested genes dramatically changed. The major sequence type changed from ST1 to ST2, and new sequence type (ST8) appeared. In the minimum spanning tree, recent isolates belonging to the ACC-I-ST3 subgroup were detected that were composed of ST2, ST3, and ST6. In particular, the ST2 frequency increased to 81%. The novel ST8 was linked to the increased frequency of ST2. In addition, toxic strains carrying the ptxP3 promoter type were confirmed. This ptxP3 type emerged from 2009 and its frequency had increased to 100% in 2012. Based on these results, it can be inferred that the genotypic changes in the currently circulating strains are strongly associated with the recent increasing of pertussis in Korea. Therefore, the surveillance system should be strengthened, and genetic characterization of the isolates should be expanded to the whole genome sequence level.
*Antigenic Variation ; Antigens/*genetics/immunology/metabolism ; Bacterial Proteins/genetics/metabolism ; Bordetella pertussis/*genetics/isolation & purification/*metabolism ; Genes, Bacterial ; Genotype ; Humans ; Pertussis Toxin/genetics/metabolism ; Promoter Regions, Genetic ; Republic of Korea ; Sequence Analysis, DNA ; Whooping Cough/immunology/*microbiology/pathology

Despite recent innovative advances in molecular virology and the developments of vaccines, influenza virus remains a serious burden for human health. Vaccination has been considered a primary countermeasure for prevention of influenza infection. Live attenuated influenza vaccines (LAIVs) are particularly attracting attention as an effective strategy due to several advantages over inactivated vaccines. Cold-adaptation, as a classical means for attenuating viral virulence, has been successfully used for generating safe and effective donor strains of LAIVs against seasonal epidemics and occasional pandemics. Recently, the advent of reverse genetics technique expedited a variety of rational strategies to broaden the pool of LAIVs. Considering the breadth of antigenic diversity of influenza virus, the pool of LAIVs is likely to equip us with better options for controlling influenza pandemics. With a brief reflection on classical attenuating strategies used at the initial stage of development of LAIVs, especially on the principles underlying the development of cold-adapted LAIVs, we further discuss and outline other attenuation strategies especially with respect to the rationales for attenuation, and their practicality for mass production. Finally, we propose important considerations for a rational vaccine design, which will provide us with practical guidelines for improving the safety and effectiveness of LAIVs.
Antigenic Variation ; Cross Protection ; Humans ; Influenza Vaccines ; Influenza, Human ; Orthomyxoviridae ; Pandemics ; Reverse Genetics ; Seasons ; Tissue Donors ; Vaccination ; Vaccines, Inactivated

OBJECTIVETo investigate the relationship between the mutation patterns of rtM204V/I (methionine to valine or isoleucine at position rt204 of reverse transcriptase domain) in hepatitis B virus (HBV) polymerase gene and HBV genotypes.

METHODSA total of 2849 HBV complete genome sequences were retrieved from the GenBank/EMBL/DDBJ. HBV genotypes were determined by using MEGA4 software. The amino acid sequences of the reverse transcriptase (RT) domain were aligned. Data were analyzed using SPSS 13.0. RESULTS Among the 2849 HBV complete genome sequences, 217 strains with Y (I/V) DD were identified. Of them, 120 had YIDD mutation and the genotype/subgenotype distribution was as follows: A (2), B(B2 19), C(C1 1, C2 78, C5 1), D(17), E(1), G(1); 97 had YVDD mutation and the genotype/subgenotype distribution was as follows: A(17), B(B2 22), C(C1 3, C2 48), D(3), G(3), H(1). There is a significant difference in the mutation patterns of Y (I/V) DD among genotypes of A-D, A-C, and between genotype A and B, P < 0.01.There is a difference in the mutation pattern of Y (I/V) DD among genotypes of B-D, between genotype C and D, P < 0.05. Genotype A has a higher tendency to develop YVDD mutation, whereas genotype D has a higher frequency to develop YIDD mutation. The rtM204V-rtL180M mutations were more frequently found in subgenotype B2 than in subgenotype C2 while the rtM204V-rtL180M-rtV173L mutations were more associated with subgenotype C2 (P < 0.01).

CONCLUSIONDifferent HBV genotype/subgenotype may select different mutation pattern in the YMDD domain. Subgenotype C2 is more diversity and complexity than other HBV genotypes/subgenotypes.

Antigenic Variation ; DNA Mutational Analysis ; DNA, Viral ; genetics ; DNA-Directed DNA Polymerase ; genetics ; Genotype ; Hepatitis B virus ; genetics ; Viral Proteins ; genetics

OBJECTIVETo study the global evolutionary characteristics of hemagglutinin gene HA1 of influenza H1N1 infecting different species during 2000-2009.

METHODSThe target sequences were downloaded from NCBI and analyzed using bioinformatic software to construct the phylogenetic tree.

RESULTSThe HA1 amino acid sequences of influenza H1N1 contained four mutated antigenic sites and receptor-binding sites, and the novel influenza virus shared most of the mutated amino acid sites with swine H1N1 influenza virus.

CONCLUSIONThe HA1 gene of novel influenza virus might originate from the early swine H1N1 influenza virus from North America, and in the evolutionary process, a number of important sites of HA1 gene mutated to result in the outbreak of influenza.

Antigenic Variation ; China ; epidemiology ; Computational Biology ; Genes, Viral ; Hemagglutinin Glycoproteins, Influenza Virus ; genetics ; Humans ; Influenza A Virus, H1N1 Subtype ; genetics ; Influenza, Human ; epidemiology ; virology ; Mutation ; Phylogeny

OBJECTIVETo explore the distinction between wild-type strain MVi/Zhejiang, CHN/7.05/4 and vaccine strain Shanghai-191 at genome level.

METHODSAfter sequencing of measles wild-stain MVi/Zhejiang. CHN/7.05/4, the distinction between the wild-type strain and the vaccine strain was analysed by MEGA 3.1 software at genome level, and the antigen variation was studied by means of combining the epidemiological data.

RESULTSThere were 822 nucleotide differences (5.17%) and 161 amino acid differences between these two strains, including three glycosylation sites variation found. Meanwhile, the antigen ratio between wild-type strain and vaccine strain was found to be 5.66.

CONCLUSIONThere should be certain differences between the contemporary wild-type strain MVi/Zhejiang, CHN/7.05/4 and vaccine strain Shanghai-191 at genome level, and the protective effects of measles vaccine should be studied further.

Antigenic Variation ; China ; epidemiology ; Comparative Genomic Hybridization ; Genome, Viral ; Humans ; Measles ; epidemiology ; prevention & control ; virology ; Measles Vaccine ; genetics ; Measles virus ; classification ; genetics ; immunology ; Sequence Analysis, Protein ; Sequence Analysis, RNA

The present study was conducted to examine the morphology and antigenicity of Photobacterium damselae subsp. piscicida by culturing the bacterium in vivo in the peritoneal cavity of sea bass (Dicentrarchus labrax) within dialysis bags with either a low molecular weight (LMW) cut-off of 25 kDa or a high molecular weight (HMW) cut-off of 300 kDa. Differences were observed in the growth rate between the bacteria cultured in vivo or in vitro. Bacteria cultured in vivo were smaller and produced a capsular layer, which was more prominent in bacteria cultured in the HMW bag. Antigenicity was examined by Western blot analysis using sera from sea bass injected with live Ph. d. subsp. piscicida. The sera recognised bands at 45 and 20 kDa in bacteria cultured in vivo in the LMW bag. Bacteria cultured in vivo in the HMW bag did not express the 45 kDa band when whole cell extracts were examined, although the antigen was present in their extracellular products. In addition, these bacteria had a band at 18 kDa rather than 20 kDa. Differences in glycoprotein were also evident between bacteria cultured in vitro and in vivo. Bacteria cultured in vitro in LMW and HMW bags displayed a single 26 kDa band. Bacteria cultured in the LMW bag in vivo displayed bands at 26 and 27 kDa, while bacteria cultured in vivo in the HMW bag possessed only the 27 kDa band. These bands may represent sialic acid. The significance of the changes observed in the bacterium's structure and antigenicity when cultured in vivo is discussed.
Animals ; Antigenic Variation/*genetics ; Antigens, Bacterial/genetics/*immunology ; Bass/*immunology/microbiology ; Blotting, Western ; Carbohydrates/analysis ; Electrophoresis, Polyacrylamide Gel ; Membranes, Artificial ; Microscopy, Electron, Transmission ; N-Acetylneuraminic Acid/genetics/*immunology ; Photobacterium/genetics/*immunology/ultrastructure

OBJECTIVETo study whether the substitutions at the major hydrophilic region II (MHRII) of hepatitis B surface antigen (HBsAg) will impair the antigenicity of HBsAg.

METHODSFour recombinant plasmids expressing mutant HBsAg (mtHBsAg) P1120T, C121S, K122I and T123N were constructed. HepG2 cells were transfected with the four plasmids and a plasmid expressing G145R HBsAg. The immunoreactivity of the cells expressing mtHBsAg with P1120T, C121S, K122I, T123N and G145R were detected by immunofluorescence (IF) staining and ELISA with 4 antibodies and 7 HBsAg diagnostic kits respectively.

RESULTSmtHBsAg with P120T was recognized by mAb1 and mAb2. mtHBsAg with C121S and K122I was not recognized by any mAbs. mtHBsAg with T123N in lysates was recognized by mAb2, but not recognized in the supernatants.

CONCLUSIONSubstitutions at amino acid positions 120-123 of HBsAg strongly impaired the antigenicity of HBsAg, a fact that was not appreciated previously.

Amino Acid Substitution ; Antigenic Variation ; Hep G2 Cells ; Hepatitis B Surface Antigens ; genetics ; immunology ; Hepatitis B virus ; genetics ; immunology ; Humans ; Mutation ; Plasmids ; Transfection

OBJECTIVETo characterize the prevalence and antigenic drift of influenza A viruses isolated during the period from 2001 to 2005 in infants and young children in Beijing.

METHODSMDCK cell culture, indirect immunofluorescence assay (IFA) and hemagglutination inhibition (HI) assay were used to isolate and identify type A influenza viruses (H1N1 and H3N2) from clinical samples collected from outpatients and inpatients who visited the Affiliated Children's Hospital because of acute respiratory infections from Oct. 2001 to Aug. 2005. The HA1 regions of hemagglutinin gene of H3N2 isolates were amplified by using RT-PCR followed by sequencing.

RESULTSOut of 7338 clinical samples collected during this surveillance period, 347 (4.7%) were positive for influenza A viruses, including 48 (13.8%) of H1N1, 273 (78.7%) of H3N2 and 26 (7.5%) of subtype-unidentified influenza A viruses. Although there was a prevalence season of influenza A from October each year to April of next year during the 2001-2004 period, it was worth noting that a consecutive influenza A activity was detected from Aug. 2004 to Aug. 2005, when some influenza A viruses were detected even in summer. The positive rate of H3N2 was 14.2% in August, 2005, which was equal to that of the peak season of 2003-2004. H3N2 were predominant in most of the influenza seasons during the surveillance period, and H1N1 was detected only in the influenza seasons of the 2001-2002 and 2004-2005 along with H3N2. The positive rates for both H3N2 and H1N1 were higher in specimens from outpatients than those from inpatients. A total of 46.6% (110/236) of the H3N2 were detected from children younger than 2 years of age, and 14.0% (33/236) were from children older than 5 years, whereas, more H1N1 was found in children older than 5 years (48.0%, 12/31) than in those younger than 2 years (6.5%, 2/31) during a period from Nov. 2003 to Aug. 2005. Sequence analysis of the HA1 regions of hemagglutinin of H3N2 isolated in a series of years revealed amino acid changes in the HA1 domain of H3N2 isolates in the antigenic sites (A-E) each year.

CONCLUSIONH3N2 and H1N1 prevailed in each influenza season during the surveillance period in Beijing, and H3N2 strains were predominant. The data from all-year around surveillance of influenza in Beijing indicate that continuous surveillance throughout a year and use of both antigenic and molecular analysis will be more helpful for early identification of any antigenic variants as well as prevention and control of influenza by promoting development of vaccines.

Age Factors ; Animals ; Antigenic Variation ; genetics ; Cell Culture Techniques ; Child ; Child, Preschool ; China ; epidemiology ; Dogs ; Female ; Hemagglutinin Glycoproteins, Influenza Virus ; genetics ; Humans ; Infant ; Influenza A Virus, H1N1 Subtype ; isolation & purification ; Influenza A Virus, H3N2 Subtype ; isolation & purification ; Influenza A virus ; classification ; genetics ; isolation & purification ; Influenza, Human ; virology ; Inpatients ; Male ; Outpatients ; Prevalence ; Respiratory Tract Infections ; virology ; Retrospective Studies ; Reverse Transcriptase Polymerase Chain Reaction ; Time Factors

OBJECTIVETo identify variations in hemagglutinin genes from influenza viruses (H3N2) isolated from infants and young children with acute respiratory infection (ARI) between March, 2004 and April 2005.

METHODSRNAs from influenza A virus strains (subtype H3) isolated from specimens collected from ARI children were extracted followed by amplification for HA1 fragments from hemagglutinin (HA) genes by RT-PCR. The sequences of the fragments were defined by direct sequencing for the PCR products or the target inserts after the PCR fragments were cloned into the TA-cloning vector pBS-T and analyzed by bioinformatic software.

RESULTSFragments of 987 bps of HA1 (encoding 329 amino acids) from a total of 32 strains of influenza A virus (subtype H3) isolated from the 2004 season and 1 from the 2003 season were amplified and the sequences were compared with vaccine reference strains recommended by WHO which were used in recent years. There were several consistent amino acid variations which involved in both antigenic epitopes A and B and receptor binding site (RBS) for isolated strains in the 2004 influenza season compared with the vaccine strains used during the recent years and the virus strains isolated in March 2004, indicated the antigenic drift of the viruses isolated in 2004 influenza season may lead to variant viruses.

CONCLUSIONThe variations of the HA genes from influenza virus (subtype H3) strains in the 2004-2005 influenza season were confirmed by sequence analysis for the HA1 regions of the hemagglutinin genes, which indicate that the antigenic drift would have been caused by the diversification of the genes and the efficacy of the recently used vaccines should be kept under close watch.

Antigenic Variation ; Child ; China ; epidemiology ; Evolution, Molecular ; Hemagglutinin Glycoproteins, Influenza Virus ; genetics ; Humans ; Influenza A Virus, H3N2 Subtype ; genetics ; immunology ; isolation & purification ; Influenza, Human ; epidemiology ; immunology ; virology ; RNA, Viral ; genetics ; Sequence Analysis, RNA