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 characteristics of the variation of antigen epitopes and quasispecies group in the HIV-1 viruses in Henan province in China.

METHODSThe region of the p17-p24 of the HIV-1 gag gene was amplified by nested polymerse chain reaction (PCR), purified products were cloned into the vector, the obtained were analyzed by MEGA soft wares.

RESULTSB' subtype strains were predominant in Henan province, the mutations in antigen epitypes of the p17 region of the gag gene focus on E62g (55.8%), Y79f (48.9%), T84V (48.9), I44V (44.2%), the p24 region had not found the distinct mutation.

CONCLUSIONBoth the PCR sequences and clone strains sequences demonstrated that four antigen epitopes mutations in p17 region of the HIV B' subtype gag gene, and the region of p24 was more conservative, which was suitable for development of the epitope vaccien.

Antigenic Variation ; China ; Epitopes ; genetics ; HIV Infections ; virology ; HIV-1 ; classification ; genetics ; isolation & purification ; Humans ; Molecular Sequence Data ; Mutation ; Phylogeny ; gag Gene Products, Human Immunodeficiency Virus ; 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 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

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

BACKGROUNDTo understand the antigenic and genetic characteristics of Victoria like strain of influenza B virus isolated recently and to provide a scientific evidence for influenza surveillance and monitoring of influenza epidemic in future.

METHODSViruses were passed in embryonated hen eggs and virion RNA was extracted from allantoic fluid and reverse transcribed to synthesize cDNA. cDNA was amplified by PCR and the PCR product was purified with a purification kit. Afterwards RNA sequence analysis was performed by dideoxynucleotide chain termination and a cloning method. Finally, phylogenetic analysis of the sequencing data was performed with MegAlign.

RESULTSB/Sichuan/63/2001 and B/Zhejiang/2/2001 viruses were antigenically different from B/Shandong/7/97 strain. The substitution of nucleotide sequences of HA1genes of them compared with those of B/Shandong/7/97strain resulted in the change of amino acid sequences in antigenic determinants on HA1 protein domain. The phylogenetic analysis also indicated that strains isolated recently were genetically different from B/Shandong/7/97/strain. However, there was neither differences on the antigenicity nor genetic partern between these two isotates.

CONCLUSIONSThe antigenic drift of Victoria-like strain of influenza B virus isolated recently in China has further occurred.

Amino Acid Sequence ; Antigenic Variation ; China ; Epitopes ; Genetic Variation ; Hemagglutinin Glycoproteins, Influenza Virus ; genetics ; immunology ; Humans ; Influenza B virus ; genetics ; immunology ; Influenza, Human ; virology ; Molecular Sequence Data ; RNA, Viral ; analysis ; Sequence Analysis, RNA

OBJECTIVEGene sequence data were clustered to explore evolution lineages of H3 antigen of influenza A virus.

METHODSAll data of H3 RNA sequence in NCBI Genbank and Influenza sequence database were downloaded and aligned in ClustalX while two step cluster method were applied to explore the data.

RESULTSAll sequences were aggregated into ten clusters, while seven of them mainly were human virus. Human virus and avian/other mammal virus were separated into different clusters distinctively, but coexisted into same clusters with swine virus. Time and host distribution were very distinctive in these clusters, but no geographic distribution features were found.

CONCLUSIONWith the interaction of human immunity system, H3 antigen mutated significantly every 5 - 7 years, and the speed of mutation had accelerated with the application of influenza vaccines in recent years. Mean while, human and swine influenza virus were not separated distinctly between clusters indicating that they had short inheritance distance. Result showed again that swine served as the mixer for antigenic recombination of different influenza virus.

Antigenic Variation ; genetics ; Antigens, Viral ; genetics ; Cluster Analysis ; Evolution, Molecular ; Hemagglutinin Glycoproteins, Influenza Virus ; genetics ; Hemagglutinins, Viral ; genetics ; immunology ; Humans ; Influenza A virus ; genetics ; immunology ; Mutation ; Sequence Analysis, DNA ; Viral Envelope Proteins ; genetics

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

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