Construction and Protective Efficacy of Egy-H5 DNA Vaccine from Local Egyptian strain H5N1 using Codon Optimized HA gene
Construction and Protective Efficacy of Egy-H5 DNA Vaccine from Local Egyptian strain H5N1 using Codon Optimized HA gene
Wesam Hasan Mohamed Mady1*, Bing Liu2, Dong Huang2, Abdel Satar Arafa1, Mohamed Khalifa Hassan1, Mona Mehrez Aly1, Pucheng Chen2, Yongping Jiang2* and Hualan Chen2
ABSTRACT
The incursion of highly pathogenic avian influenza virus (HPAIV) strain H5N1 in 2006 in Egypt caused severe economic losses for both commercial and backyard poultry production sectors. Owing to public health risk, effective control of the virus in imperative. DNA vaccination is a promising new approach for the prevention and treatment of many viral diseases because of its ability to induce both humoral and cellular immune responses against antigens encoded by recombinant DNA. The goal of this study was to construct Egy-H5 plasmid DNA-based vaccine against a currently circulating avian influenza virus H5N1 strain in Egypt targeting the HA gene. The HA gene of AIV Egyptian strain H5N1 was codon optimized for chicken biased codon and sub-cloned into pCAGGS mammalian expression vector under the control of chicken β-actin promoter. The construct was transfected into 293T HEK (Human Embryonic Kidney) cell line for in vitro expression of the recombinant plasmid DNA. The confirmation of H5 protein expression was performed using SDS-PAGE followed by Western blotting and immunofluorescence assays. The humoral immune response was evaluated by intramuscular immunization of specific pathogen free (SPF) chickens with two different concentrations of Egy-H5 plasmid DNA 15µg and 60 µg. Results demonstrate that chickens developed detectable HI antibody titers up to 6log2 within two weeks post-booster vaccination. The challenge experiment was performed using isolate A/chicken/Egypt/A6/2011 (H5N1) with concentration of 105 EID50 to evaluate the protective efficacy of the Egy-H5 plasmid DNA vaccine. The Egy-H5 plasmid DNA vaccine induced complete protection (100%) and there was no virus shedding in all chickens immunized with the Egy-H5 plasmid DNA vaccine. Taken together, the presented immunization approach is an alternative strategy to not only control the infections in chicken but also to safeguard public health.
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