Influenza, caused by influenza virus, is a serious respiratory illness which poses a global public health threat. Vaccination is the primary strategy for the prevention and control of influenza. Although both inactivated vaccines and the live attenuated vaccines are effective in preventing influenza, the current vaccines have poor efficacy in the elderly and fail to provide protection against heterosubtype viruses. Development of a safer and more effective influenza vaccine that provides broad cross protection, overcoming the intrinsic limitation of the current vaccines, has been a scientific challenge. During the past decades, structural biology, reverse genetic and other virological technologies developed quickly and sped the progress of influenza vaccinology. Some new strategies for developing influenza vaccine have been generated, produced encouraging results, which showed great prospect as next-generation of influenza vaccines.
Disease Outbreaks ; prevention & control ; Hemagglutinin Glycoproteins, Influenza Virus ; immunology ; Humans ; Influenza Vaccines ; biosynthesis ; immunology ; Influenza, Human ; immunology ; prevention & control ; virology ; Orthomyxoviridae ; immunology ; Vaccines, Attenuated ; immunology ; Vaccines, Inactivated ; immunology

To use the designed restriction enzyme assisted mutagenesis technique to perform rapid site-directed mutagenesis on double-stranded plasmid DNA. The target amino acid sequence was reversely translated into DNA sequences with degenerate codons, resulting in large amount of silently mutated sequences containing various restriction endonucleases (REs). Certain mutated sequence with an appropriate RE was selected as the target DNA sequence for designing mutation primers. The full-length plasmid DNA was amplified with high-fidelity Phusion DNA polymerase and the amplified product was 5' phosphorylated by T4 polynucleotide kinase and then self-ligated. After transformation into an E. coli host the transformants were rapidly screened by cutting with the designed RE. With this strategy we successfully performed the site-directed mutagenesis on an 8 kb plasmid pcDNA3.1-pIgR and recovered the wild-type amino acid sequence of human polymeric immunoglobulin receptor (pIgR). A novel site-directed mutagenesis strategy based on DREAM was developed which exploited RE as a rapid screening measure. The highly efficient, high-fidelity Phusion DNA polymerase was applied to ensure the efficient and faithful amplification of the full-length sequence of a plasmid of up to 8 kb. This rapid mutagenesis strategy avoids using any commercial site-directed mutagenesis kits, special host strains or isotopes.
Amino Acid Sequence ; Base Sequence ; DNA ; genetics ; DNA Restriction Enzymes ; genetics ; DNA-Directed DNA Polymerase ; genetics ; Molecular Sequence Data ; Mutagenesis, Site-Directed ; methods ; Plasmids ; Receptors, Polymeric Immunoglobulin ; genetics

Abstract: To express human-mouse chimeric IgA antibody directed against H5N1 virus, an anti-H5N1 chimeric IgA antibody gene was constructed by joining the light and heavy chain variable region genes and the corresponding signal peptide coding sequences of the anti-H5N1 mouse monoclonal antibody H5N1-HA with the coding sequences of the constant region of the human IgA2 heavy chain and Kappa chain respectively. Then the full-length chimeric light and heavy chain expressing plasmids pEF-IGHA9 and pEF-IGK9 were constructed and transfected into the CHO/dhfr cells. The chimeric IgA antibody expression was confirmed by ELISA, SDS-PAGE and Western blotting. The successful expression of this anti-H5N1 chimeric IgA may help to provide a stand for developing passive immunological agents for H5N1 virus infection prophylaxis.
Animals ; Antibodies, Monoclonal ; biosynthesis ; Antibodies, Viral ; genetics ; CHO Cells ; Chimerism ; Cricetinae ; Cricetulus ; Humans ; Immunoglobulin A ; genetics ; immunology ; Influenza A Virus, H5N1 Subtype ; genetics ; immunology ; Mice ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; immunology

Improving expression of antigen is critical to the immunogenicity of DNA vaccines. To achieve this goal, we modified the NDV F48E9 strain HN gene by optimizing the condon usage and inserting the secretary leader sequence [A/Goose/Guangdong/1/96 (H5N1) HA gene, Accession No. AF144305]. The HN gene modified and knocked the signal peptide off were named SoptiHN and optiHN. The three sequence: SoptiHN, optiHN and the NDV F48E9 strain HN gene were inserted into the vector pVAX1 and vector pVAX1-CpG including CpG-ODN sequence respectively. Then we got six recombinant plasmids: pV-SoptiHN, pVC-SoptiHN, pV-optiHN, pVC-optiHN, pV-HN and pVC-HN. By optimizing condon usage in transiently transfected 293T cells, expression levels of HN gene were higher from the codon-optimized gene than the counterpart. Moreover, both optimization of condon usage and addition of signal peptide could improve expression of HN gene in vitro.
Animals ; Chickens ; Codon ; HN Protein ; genetics ; Hemagglutinin Glycoproteins, Influenza Virus ; genetics ; Influenza A Virus, H5N1 Subtype ; genetics ; Newcastle Disease ; immunology ; prevention & control ; Newcastle disease virus ; classification ; genetics ; Vaccines, DNA ; genetics ; immunology ; Viral Vaccines ; genetics ; immunology